summaryrefslogtreecommitdiffstats
path: root/doc/history.html
blob: 3110cf3546282c70b8fb3d533d23cd65e44d26a2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
<HTML>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<!-- Created on October, 30  2020 by texi2html 1.64 -->
<!-- 
Written by: Lionel Cons <Lionel.Cons@cern.ch> (original author)
            Karl Berry  <karl@freefriends.org>
            Olaf Bachmann <obachman@mathematik.uni-kl.de>
            and many others.
Maintained by: Olaf Bachmann <obachman@mathematik.uni-kl.de>
Send bugs and suggestions to <texi2html@mathematik.uni-kl.de>
 
-->
<HEAD>
<TITLE>GNU History Library: </TITLE>

<META NAME="description" CONTENT="GNU History Library: ">
<META NAME="keywords" CONTENT="GNU History Library: ">
<META NAME="resource-type" CONTENT="document">
<META NAME="distribution" CONTENT="global">
<META NAME="Generator" CONTENT="texi2html 1.64">

</HEAD>

<BODY LANG="" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#800080" ALINK="#FF0000">

<A NAME="SEC_Top"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H1>GNU History Library</H1></P><P>

This document describes the GNU History library, a programming tool that
provides a consistent user interface for recalling lines of previously
typed input.
</P><P>

<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0> 
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC1">1. Using History Interactively</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">GNU History User's Manual.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC6">2. Programming with GNU History</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">GNU History Programmer's Manual.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC19">A. GNU Free Documentation License</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">License for copying this manual.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC21">B. Concept Index</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Index of concepts described in this manual.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC22">C. Function and Variable Index</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Index of externally visible functions
				  and variables.</TD></TR>
</TABLE></BLOCKQUOTE>
<P>

<HR SIZE=1>
<A NAME="SEC1"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC2"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[ &lt;&lt; ]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC6"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<A NAME="Using History Interactively"></A>
<H1> 1. Using History Interactively </H1>
<!--docid::SEC1::-->
<P>

This chapter describes how to use the GNU History Library interactively,
from a user's standpoint.  It should be considered a user's guide.  For
information on using the GNU History Library in your own programs,
see section <A HREF="history.html#SEC6">2. Programming with GNU History</A>.
</P><P>

<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0> 
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC2">1.1 History Expansion</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">What it feels like using History as a user.</TD></TR>
</TABLE></BLOCKQUOTE>
<P>

<A NAME="History Interaction"></A>
<HR SIZE="6">
<A NAME="SEC2"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC1"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC3"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[ &lt;&lt; ]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC1"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC6"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H2> 1.1 History Expansion </H2>
<!--docid::SEC2::-->
<P>

The History library provides a history expansion feature that is similar
to the history expansion provided by <CODE>csh</CODE>.  This section
describes the syntax used to manipulate the history information.
</P><P>

History expansions introduce words from the history list into
the input stream, making it easy to repeat commands, insert the
arguments to a previous command into the current input line, or
fix errors in previous commands quickly.
</P><P>

History expansion takes place in two parts.  The first is to determine
which line from the history list should be used during substitution.
The second is to select portions of that line for inclusion into the
current one.  The line selected from the history is called the
<EM>event</EM>, and the portions of that line that are acted upon are
called <EM>words</EM>.  Various <EM>modifiers</EM> are available to manipulate
the selected words.  The line is broken into words in the same fashion
that Bash does, so that several words
surrounded by quotes are considered one word.
History expansions are introduced by the appearance of the
history expansion character, which is <SAMP>`!'</SAMP> by default.
</P><P>

History expansion implements shell-like quoting conventions:
a backslash can be used to remove the special handling for the next character;
single quotes enclose verbatim sequences of characters, and can be used to
inhibit history expansion;
and characters enclosed within double quotes may be subject to history
expansion, since backslash can escape the history expansion character,
but single quotes may not, since they are not treated specially within
double quotes.
</P><P>

<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0> 
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC3">1.1.1 Event Designators</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">How to specify which history line to use.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC4">1.1.2 Word Designators</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Specifying which words are of interest.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC5">1.1.3 Modifiers</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Modifying the results of substitution.</TD></TR>
</TABLE></BLOCKQUOTE>
<P>

<A NAME="Event Designators"></A>
<HR SIZE="6">
<A NAME="SEC3"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC2"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC4"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[ &lt;&lt; ]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC2"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC6"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H3> 1.1.1 Event Designators </H3>
<!--docid::SEC3::-->
<P>

An event designator is a reference to a command line entry in the
history list.
Unless the reference is absolute, events are relative to the current
position in the history list.
<A NAME="IDX1"></A>
</P><P>

<DL COMPACT>

<DT><CODE>!</CODE>
<DD>Start a history substitution, except when followed by a space, tab,
the end of the line, or <SAMP>`='</SAMP>.
<P>

<DT><CODE>!<VAR>n</VAR></CODE>
<DD>Refer to command line <VAR>n</VAR>.
<P>

<DT><CODE>!-<VAR>n</VAR></CODE>
<DD>Refer to the command <VAR>n</VAR> lines back.
<P>

<DT><CODE>!!</CODE>
<DD>Refer to the previous command.  This is a synonym for <SAMP>`!-1'</SAMP>.
<P>

<DT><CODE>!<VAR>string</VAR></CODE>
<DD>Refer to the most recent command
preceding the current position in the history list
starting with <VAR>string</VAR>.
<P>

<DT><CODE>!?<VAR>string</VAR>[?]</CODE>
<DD>Refer to the most recent command
preceding the current position in the history list
containing <VAR>string</VAR>.
The trailing
<SAMP>`?'</SAMP> may be omitted if the <VAR>string</VAR> is followed immediately by
a newline.
If <VAR>string</VAR> is missing, the string from the most recent search is used;
it is an error if there is no previous search string.
<P>

<DT><CODE>^<VAR>string1</VAR>^<VAR>string2</VAR>^</CODE>
<DD>Quick Substitution.  Repeat the last command, replacing <VAR>string1</VAR>
with <VAR>string2</VAR>.  Equivalent to
<CODE>!!:s^<VAR>string1</VAR>^<VAR>string2</VAR>^</CODE>.
<P>

<DT><CODE>!#</CODE>
<DD>The entire command line typed so far.
<P>

</DL>
<P>

<A NAME="Word Designators"></A>
<HR SIZE="6">
<A NAME="SEC4"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC3"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC5"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC5"> &lt;&lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC2"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC6"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H3> 1.1.2 Word Designators </H3>
<!--docid::SEC4::-->
<P>

Word designators are used to select desired words from the event.
A <SAMP>`:'</SAMP> separates the event specification from the word designator.  It
may be omitted if the word designator begins with a <SAMP>`^'</SAMP>, <SAMP>`$'</SAMP>,
<SAMP>`*'</SAMP>, <SAMP>`-'</SAMP>, or <SAMP>`%'</SAMP>.  Words are numbered from the beginning
of the line, with the first word being denoted by 0 (zero).  Words are
inserted into the current line separated by single spaces.
</P><P>

For example,
</P><P>

<DL COMPACT>
<DT><CODE>!!</CODE>
<DD>designates the preceding command.  When you type this, the preceding
command is repeated in toto.
<P>

<DT><CODE>!!:$</CODE>
<DD>designates the last argument of the preceding command.  This may be
shortened to <CODE>!$</CODE>.
<P>

<DT><CODE>!fi:2</CODE>
<DD>designates the second argument of the most recent command starting with
the letters <CODE>fi</CODE>.
</DL>
<P>

Here are the word designators:
 
<DL COMPACT>

<DT><CODE>0 (zero)</CODE>
<DD>The <CODE>0</CODE>th word.  For many applications, this is the command word.
<P>

<DT><CODE><VAR>n</VAR></CODE>
<DD>The <VAR>n</VAR>th word.
<P>

<DT><CODE>^</CODE>
<DD>The first argument; that is, word 1.
<P>

<DT><CODE>$</CODE>
<DD>The last argument.
<P>

<DT><CODE>%</CODE>
<DD>The first word matched by the most recent <SAMP>`?<VAR>string</VAR>?'</SAMP> search,
if the search string begins with a character that is part of a word.
<P>

<DT><CODE><VAR>x</VAR>-<VAR>y</VAR></CODE>
<DD>A range of words; <SAMP>`-<VAR>y</VAR>'</SAMP> abbreviates <SAMP>`0-<VAR>y</VAR>'</SAMP>.
<P>

<DT><CODE>*</CODE>
<DD>All of the words, except the <CODE>0</CODE>th.  This is a synonym for <SAMP>`1-$'</SAMP>.
It is not an error to use <SAMP>`*'</SAMP> if there is just one word in the event;
the empty string is returned in that case.
<P>

<DT><CODE><VAR>x</VAR>*</CODE>
<DD>Abbreviates <SAMP>`<VAR>x</VAR>-$'</SAMP>
<P>

<DT><CODE><VAR>x</VAR>-</CODE>
<DD>Abbreviates <SAMP>`<VAR>x</VAR>-$'</SAMP> like <SAMP>`<VAR>x</VAR>*'</SAMP>, but omits the last word.
If <SAMP>`x'</SAMP> is missing, it defaults to 0.
<P>

</DL>
<P>

If a word designator is supplied without an event specification, the
previous command is used as the event.
</P><P>

<A NAME="Modifiers"></A>
<HR SIZE="6">
<A NAME="SEC5"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC4"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC6"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[ &lt;&lt; ]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC2"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC6"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H3> 1.1.3 Modifiers </H3>
<!--docid::SEC5::-->
<P>

After the optional word designator, you can add a sequence of one or more
of the following modifiers, each preceded by a <SAMP>`:'</SAMP>.
These modify, or edit, the word or words selected from the history event.
</P><P>

<DL COMPACT>

<DT><CODE>h</CODE>
<DD>Remove a trailing pathname component, leaving only the head.
<P>

<DT><CODE>t</CODE>
<DD>Remove all leading pathname components, leaving the tail.
<P>

<DT><CODE>r</CODE>
<DD>Remove a trailing suffix of the form <SAMP>`.<VAR>suffix</VAR>'</SAMP>, leaving
the basename.
<P>

<DT><CODE>e</CODE>
<DD>Remove all but the trailing suffix.
<P>

<DT><CODE>p</CODE>
<DD>Print the new command but do not execute it.
<P>

<DT><CODE>s/<VAR>old</VAR>/<VAR>new</VAR>/</CODE>
<DD>Substitute <VAR>new</VAR> for the first occurrence of <VAR>old</VAR> in the
event line.
Any character may be used as the delimiter in place of <SAMP>`/'</SAMP>.
The delimiter may be quoted in <VAR>old</VAR> and <VAR>new</VAR>
with a single backslash.  If <SAMP>`&#38;'</SAMP> appears in <VAR>new</VAR>,
it is replaced by <VAR>old</VAR>.  A single backslash will quote
the <SAMP>`&#38;'</SAMP>.
If <VAR>old</VAR> is null, it is set to the last <VAR>old</VAR>
substituted, or, if no previous history substitutions took place,
the last <VAR>string</VAR>
in a !?<VAR>string</VAR><CODE>[?]</CODE>
search.
If <VAR>new</VAR> is is null, each matching <VAR>old</VAR> is deleted.
The final delimiter is optional if it is the last
character on the input line.
<P>

<DT><CODE>&#38;</CODE>
<DD>Repeat the previous substitution.
<P>

<DT><CODE>g</CODE>
<DD><DT><CODE>a</CODE>
<DD>Cause changes to be applied over the entire event line.  Used in
conjunction with <SAMP>`s'</SAMP>, as in <CODE>gs/<VAR>old</VAR>/<VAR>new</VAR>/</CODE>,
or with <SAMP>`&#38;'</SAMP>.
<P>

<DT><CODE>G</CODE>
<DD>Apply the following <SAMP>`s'</SAMP> or <SAMP>`&#38;'</SAMP> modifier once to each word
in the event.
<P>

</DL>
<P>

<A NAME="Programming with GNU History"></A>
<HR SIZE="6">
<A NAME="SEC6"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC5"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC7"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[ &lt;&lt; ]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC19"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H1> 2. Programming with GNU History </H1>
<!--docid::SEC6::-->
<P>

This chapter describes how to interface programs that you write
with the GNU History Library.
It should be considered a technical guide.
For information on the interactive use of GNU History, see section <A HREF="history.html#SEC1">1. Using History Interactively</A>.
</P><P>

<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0> 
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC7">2.1 Introduction to History</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">What is the GNU History library for?</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC8">2.2 History Storage</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">How information is stored.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC9">2.3 History Functions</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Functions that you can use.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC17">2.4 History Variables</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Variables that control behaviour.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC18">2.5 History Programming Example</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Example of using the GNU History Library.</TD></TR>
</TABLE></BLOCKQUOTE>
<P>

<A NAME="Introduction to History"></A>
<HR SIZE="6">
<A NAME="SEC7"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC6"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC8"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[ &lt;&lt; ]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC6"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC19"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H2> 2.1 Introduction to History </H2>
<!--docid::SEC7::-->
<P>

Many programs read input from the user a line at a time.  The GNU
History library is able to keep track of those lines, associate arbitrary
data with each line, and utilize information from previous lines in
composing new ones. 
</P><P>

A programmer using the History library has available functions
for remembering lines on a history list, associating arbitrary data
with a line, removing lines from the list, searching through the list
for a line containing an arbitrary text string, and referencing any line
in the list directly.  In addition, a history <EM>expansion</EM> function
is available which provides for a consistent user interface across
different programs.
</P><P>

The user using programs written with the History library has the
benefit of a consistent user interface with a set of well-known
commands for manipulating the text of previous lines and using that text
in new commands.  The basic history manipulation commands are similar to
the history substitution provided by <CODE>csh</CODE>.
</P><P>

The programmer can also use the Readline library, which
includes some history manipulation by default, and has the added
advantage of command line editing.
</P><P>

Before declaring any functions using any functionality the History
library provides in other code, an application writer should include
the file <CODE>&#60;readline/history.h&#62;</CODE> in any file that uses the
History library's features.  It supplies extern declarations for all
of the library's public functions and variables, and declares all of
the public data structures.
</P><P>

<A NAME="History Storage"></A>
<HR SIZE="6">
<A NAME="SEC8"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC7"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC9"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC9"> &lt;&lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC6"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC19"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H2> 2.2 History Storage </H2>
<!--docid::SEC8::-->
<P>

The history list is an array of history entries.  A history entry is
declared as follows:
</P><P>

<TABLE><tr><td>&nbsp;</td><td class=example><pre>typedef void *histdata_t;

typedef struct _hist_entry {
  char *line;
  char *timestamp;
  histdata_t data;
} HIST_ENTRY;
</pre></td></tr></table></P><P>

The history list itself might therefore be declared as
</P><P>

<TABLE><tr><td>&nbsp;</td><td class=example><pre>HIST_ENTRY **the_history_list;
</pre></td></tr></table></P><P>

The state of the History library is encapsulated into a single structure:
</P><P>

<TABLE><tr><td>&nbsp;</td><td class=example><pre>/*
 * A structure used to pass around the current state of the history.
 */
typedef struct _hist_state {
  HIST_ENTRY **entries; /* Pointer to the entries themselves. */
  int offset;           /* The location pointer within this array. */
  int length;           /* Number of elements within this array. */
  int size;             /* Number of slots allocated to this array. */
  int flags;
} HISTORY_STATE;
</pre></td></tr></table></P><P>

If the flags member includes <CODE>HS_STIFLED</CODE>, the history has been
stifled.
</P><P>

<A NAME="History Functions"></A>
<HR SIZE="6">
<A NAME="SEC9"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC8"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC10"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC17"> &lt;&lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC6"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC17"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H2> 2.3 History Functions </H2>
<!--docid::SEC9::-->
<P>

This section describes the calling sequence for the various functions
exported by the GNU History library.
</P><P>

<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0> 
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC10">2.3.1 Initializing History and State Management</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Functions to call when you
						want to use history in a
						program.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Functions used to manage the list
					of history entries.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC12">2.3.3 Information About the History List</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Functions returning information about
					the history list.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC13">2.3.4 Moving Around the History List</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Functions used to change the position
					in the history list.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC14">2.3.5 Searching the History List</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Functions to search the history list
					for entries containing a string.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC15">2.3.6 Managing the History File</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Functions that read and write a file
					containing the history list.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC16">2.3.7 History Expansion</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Functions to perform csh-like history
					expansion.</TD></TR>
</TABLE></BLOCKQUOTE>
<P>

<A NAME="Initializing History and State Management"></A>
<HR SIZE="6">
<A NAME="SEC10"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC9"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC11"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC17"> &lt;&lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC9"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC17"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H3> 2.3.1 Initializing History and State Management </H3>
<!--docid::SEC10::-->
<P>

This section describes functions used to initialize and manage
the state of the History library when you want to use the history
functions in your program.
</P><P>

<A NAME="IDX2"></A>
<DL>
<DT><U>Function:</U> void <B>using_history</B> <I>(void)</I>
<DD>Begin a session in which the history functions might be used.  This
initializes the interactive variables.
</DL>
</P><P>

<A NAME="IDX3"></A>
<DL>
<DT><U>Function:</U> HISTORY_STATE * <B>history_get_history_state</B> <I>(void)</I>
<DD>Return a structure describing the current state of the input history.
</DL>
</P><P>

<A NAME="IDX4"></A>
<DL>
<DT><U>Function:</U> void <B>history_set_history_state</B> <I>(HISTORY_STATE *state)</I>
<DD>Set the state of the history list according to <VAR>state</VAR>.
</DL>
</P><P>

<A NAME="History List Management"></A>
<HR SIZE="6">
<A NAME="SEC11"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC10"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC12"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC12"> &lt;&lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC9"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC17"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H3> 2.3.2 History List Management </H3>
<!--docid::SEC11::-->
<P>

These functions manage individual entries on the history list, or set
parameters managing the list itself.
</P><P>

<A NAME="IDX5"></A>
<DL>
<DT><U>Function:</U> void <B>add_history</B> <I>(const char *string)</I>
<DD>Place <VAR>string</VAR> at the end of the history list.  The associated data
field (if any) is set to <CODE>NULL</CODE>.
If the maximum number of history entries has been set using
<CODE>stifle_history()</CODE>, and the new number of history entries would exceed
that maximum, the oldest history entry is removed.
</DL>
</P><P>

<A NAME="IDX6"></A>
<DL>
<DT><U>Function:</U> void <B>add_history_time</B> <I>(const char *string)</I>
<DD>Change the time stamp associated with the most recent history entry to
<VAR>string</VAR>.
</DL>
</P><P>

<A NAME="IDX7"></A>
<DL>
<DT><U>Function:</U> HIST_ENTRY * <B>remove_history</B> <I>(int which)</I>
<DD>Remove history entry at offset <VAR>which</VAR> from the history.  The
removed element is returned so you can free the line, data,
and containing structure.
</DL>
</P><P>

<A NAME="IDX8"></A>
<DL>
<DT><U>Function:</U> histdata_t <B>free_history_entry</B> <I>(HIST_ENTRY *histent)</I>
<DD>Free the history entry <VAR>histent</VAR> and any history library private
data associated with it.  Returns the application-specific data
so the caller can dispose of it.
</DL>
</P><P>

<A NAME="IDX9"></A>
<DL>
<DT><U>Function:</U> HIST_ENTRY * <B>replace_history_entry</B> <I>(int which, const char *line, histdata_t data)</I>
<DD>Make the history entry at offset <VAR>which</VAR> have <VAR>line</VAR> and <VAR>data</VAR>.
This returns the old entry so the caller can dispose of any
application-specific data.  In the case
of an invalid <VAR>which</VAR>, a <CODE>NULL</CODE> pointer is returned.
</DL>
</P><P>

<A NAME="IDX10"></A>
<DL>
<DT><U>Function:</U> void <B>clear_history</B> <I>(void)</I>
<DD>Clear the history list by deleting all the entries.
</DL>
</P><P>

<A NAME="IDX11"></A>
<DL>
<DT><U>Function:</U> void <B>stifle_history</B> <I>(int max)</I>
<DD>Stifle the history list, remembering only the last <VAR>max</VAR> entries.
The history list will contain only <VAR>max</VAR> entries at a time.
</DL>
</P><P>

<A NAME="IDX12"></A>
<DL>
<DT><U>Function:</U> int <B>unstifle_history</B> <I>(void)</I>
<DD>Stop stifling the history.  This returns the previously-set
maximum number of history entries (as set by <CODE>stifle_history()</CODE>).
The value is positive if the history was
stifled, negative if it wasn't.
</DL>
</P><P>

<A NAME="IDX13"></A>
<DL>
<DT><U>Function:</U> int <B>history_is_stifled</B> <I>(void)</I>
<DD>Returns non-zero if the history is stifled, zero if it is not.
</DL>
</P><P>

<A NAME="Information About the History List"></A>
<HR SIZE="6">
<A NAME="SEC12"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC11"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC13"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC13"> &lt;&lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC9"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC17"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H3> 2.3.3 Information About the History List </H3>
<!--docid::SEC12::-->
<P>

These functions return information about the entire history list or
individual list entries.
</P><P>

<A NAME="IDX14"></A>
<DL>
<DT><U>Function:</U> HIST_ENTRY ** <B>history_list</B> <I>(void)</I>
<DD>Return a <CODE>NULL</CODE> terminated array of <CODE>HIST_ENTRY *</CODE> which is the
current input history.  Element 0 of this list is the beginning of time.
If there is no history, return <CODE>NULL</CODE>.
</DL>
</P><P>

<A NAME="IDX15"></A>
<DL>
<DT><U>Function:</U> int <B>where_history</B> <I>(void)</I>
<DD>Returns the offset of the current history element.
</DL>
</P><P>

<A NAME="IDX16"></A>
<DL>
<DT><U>Function:</U> HIST_ENTRY * <B>current_history</B> <I>(void)</I>
<DD>Return the history entry at the current position, as determined by
<CODE>where_history()</CODE>.  If there is no entry there, return a <CODE>NULL</CODE>
pointer.
</DL>
</P><P>

<A NAME="IDX17"></A>
<DL>
<DT><U>Function:</U> HIST_ENTRY * <B>history_get</B> <I>(int offset)</I>
<DD>Return the history entry at position <VAR>offset</VAR>.
The range of valid
values of <VAR>offset</VAR> starts at <CODE>history_base</CODE> and ends at
<VAR>history_length</VAR> - 1 (see section <A HREF="history.html#SEC17">2.4 History Variables</A>).
If there is no entry there, or if <VAR>offset</VAR> is outside the valid
range, return a <CODE>NULL</CODE> pointer.
</DL>
</P><P>

<A NAME="IDX18"></A>
<DL>
<DT><U>Function:</U> time_t <B>history_get_time</B> <I>(HIST_ENTRY *entry)</I>
<DD>Return the time stamp associated with the history entry <VAR>entry</VAR>.
If the timestamp is missing or invalid, return 0.
</DL>
</P><P>

<A NAME="IDX19"></A>
<DL>
<DT><U>Function:</U> int <B>history_total_bytes</B> <I>(void)</I>
<DD>Return the number of bytes that the primary history entries are using.
This function returns the sum of the lengths of all the lines in the
history.
</DL>
</P><P>

<A NAME="Moving Around the History List"></A>
<HR SIZE="6">
<A NAME="SEC13"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC12"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC14"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC14"> &lt;&lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC9"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC17"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H3> 2.3.4 Moving Around the History List </H3>
<!--docid::SEC13::-->
<P>

These functions allow the current index into the history list to be
set or changed.
</P><P>

<A NAME="IDX20"></A>
<DL>
<DT><U>Function:</U> int <B>history_set_pos</B> <I>(int pos)</I>
<DD>Set the current history offset to <VAR>pos</VAR>, an absolute index
into the list.
Returns 1 on success, 0 if <VAR>pos</VAR> is less than zero or greater
than the number of history entries.
</DL>
</P><P>

<A NAME="IDX21"></A>
<DL>
<DT><U>Function:</U> HIST_ENTRY * <B>previous_history</B> <I>(void)</I>
<DD>Back up the current history offset to the previous history entry, and
return a pointer to that entry.  If there is no previous entry, return
a <CODE>NULL</CODE> pointer.
</DL>
</P><P>

<A NAME="IDX22"></A>
<DL>
<DT><U>Function:</U> HIST_ENTRY * <B>next_history</B> <I>(void)</I>
<DD>If the current history offset refers to a valid history entry,
increment the current history offset.
If the possibly-incremented history offset refers to a valid history
entry, return a pointer to that entry;
otherwise, return a <CODE>BNULL</CODE> pointer.
</DL>
</P><P>

<A NAME="Searching the History List"></A>
<HR SIZE="6">
<A NAME="SEC14"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC13"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC15"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC15"> &lt;&lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC9"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC17"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H3> 2.3.5 Searching the History List </H3>
<!--docid::SEC14::-->
<P>

These functions allow searching of the history list for entries containing
a specific string.  Searching may be performed both forward and backward
from the current history position.  The search may be <EM>anchored</EM>,
meaning that the string must match at the beginning of the history entry.
<A NAME="IDX23"></A>
</P><P>

<A NAME="IDX24"></A>
<DL>
<DT><U>Function:</U> int <B>history_search</B> <I>(const char *string, int direction)</I>
<DD>Search the history for <VAR>string</VAR>, starting at the current history offset.
If <VAR>direction</VAR> is less than 0, then the search is through
previous entries, otherwise through subsequent entries.
If <VAR>string</VAR> is found, then
the current history index is set to that history entry, and the value
returned is the offset in the line of the entry where
<VAR>string</VAR> was found.  Otherwise, nothing is changed, and a -1 is
returned.
</DL>
</P><P>

<A NAME="IDX25"></A>
<DL>
<DT><U>Function:</U> int <B>history_search_prefix</B> <I>(const char *string, int direction)</I>
<DD>Search the history for <VAR>string</VAR>, starting at the current history
offset.  The search is anchored: matching lines must begin with
<VAR>string</VAR>.  If <VAR>direction</VAR> is less than 0, then the search is
through previous entries, otherwise through subsequent entries.
If <VAR>string</VAR> is found, then the
current history index is set to that entry, and the return value is 0. 
Otherwise, nothing is changed, and a -1 is returned. 
</DL>
</P><P>

<A NAME="IDX26"></A>
<DL>
<DT><U>Function:</U> int <B>history_search_pos</B> <I>(const char *string, int direction, int pos)</I>
<DD>Search for <VAR>string</VAR> in the history list, starting at <VAR>pos</VAR>, an
absolute index into the list.  If <VAR>direction</VAR> is negative, the search
proceeds backward from <VAR>pos</VAR>, otherwise forward.  Returns the absolute
index of the history element where <VAR>string</VAR> was found, or -1 otherwise.
</DL>
</P><P>

<A NAME="Managing the History File"></A>
<HR SIZE="6">
<A NAME="SEC15"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC14"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC16"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC16"> &lt;&lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC9"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC17"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H3> 2.3.6 Managing the History File </H3>
<!--docid::SEC15::-->
<P>

The History library can read the history from and write it to a file.
This section documents the functions for managing a history file.
</P><P>

<A NAME="IDX27"></A>
<DL>
<DT><U>Function:</U> int <B>read_history</B> <I>(const char *filename)</I>
<DD>Add the contents of <VAR>filename</VAR> to the history list, a line at a time.
If <VAR>filename</VAR> is <CODE>NULL</CODE>, then read from <TT>`~/.history'</TT>.
Returns 0 if successful, or <CODE>errno</CODE> if not.
</DL>
</P><P>

<A NAME="IDX28"></A>
<DL>
<DT><U>Function:</U> int <B>read_history_range</B> <I>(const char *filename, int from, int to)</I>
<DD>Read a range of lines from <VAR>filename</VAR>, adding them to the history list.
Start reading at line <VAR>from</VAR> and end at <VAR>to</VAR>.
If <VAR>from</VAR> is zero, start at the beginning.  If <VAR>to</VAR> is less than
<VAR>from</VAR>, then read until the end of the file.  If <VAR>filename</VAR> is
<CODE>NULL</CODE>, then read from <TT>`~/.history'</TT>.  Returns 0 if successful,
or <CODE>errno</CODE> if not.
</DL>
</P><P>

<A NAME="IDX29"></A>
<DL>
<DT><U>Function:</U> int <B>write_history</B> <I>(const char *filename)</I>
<DD>Write the current history to <VAR>filename</VAR>, overwriting <VAR>filename</VAR>
if necessary.
If <VAR>filename</VAR> is <CODE>NULL</CODE>, then write the history list to
<TT>`~/.history'</TT>.
Returns 0 on success, or <CODE>errno</CODE> on a read or write error.
</DL>
</P><P>

<A NAME="IDX30"></A>
<DL>
<DT><U>Function:</U> int <B>append_history</B> <I>(int nelements, const char *filename)</I>
<DD>Append the last <VAR>nelements</VAR> of the history list to <VAR>filename</VAR>.
If <VAR>filename</VAR> is <CODE>NULL</CODE>, then append to <TT>`~/.history'</TT>.
Returns 0 on success, or <CODE>errno</CODE> on a read or write error.
</DL>
</P><P>

<A NAME="IDX31"></A>
<DL>
<DT><U>Function:</U> int <B>history_truncate_file</B> <I>(const char *filename, int nlines)</I>
<DD>Truncate the history file <VAR>filename</VAR>, leaving only the last
<VAR>nlines</VAR> lines.
If <VAR>filename</VAR> is <CODE>NULL</CODE>, then <TT>`~/.history'</TT> is truncated.
Returns 0 on success, or <CODE>errno</CODE> on failure.
</DL>
</P><P>

<A NAME="History Expansion"></A>
<HR SIZE="6">
<A NAME="SEC16"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC15"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC17"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC17"> &lt;&lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC9"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC17"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H3> 2.3.7 History Expansion </H3>
<!--docid::SEC16::-->
<P>

These functions implement history expansion.
</P><P>

<A NAME="IDX32"></A>
<DL>
<DT><U>Function:</U> int <B>history_expand</B> <I>(char *string, char **output)</I>
<DD>Expand <VAR>string</VAR>, placing the result into <VAR>output</VAR>, a pointer
to a string (see section <A HREF="history.html#SEC2">1.1 History Expansion</A>).  Returns:
<DL COMPACT>
<DT><CODE>0</CODE>
<DD>If no expansions took place (or, if the only change in
the text was the removal of escape characters preceding the history expansion
character);
<DT><CODE>1</CODE>
<DD>if expansions did take place;
<DT><CODE>-1</CODE>
<DD>if there was an error in expansion;
<DT><CODE>2</CODE>
<DD>if the returned line should be displayed, but not executed,
as with the <CODE>:p</CODE> modifier (see section <A HREF="history.html#SEC5">1.1.3 Modifiers</A>).
</DL>
<P>

If an error occurred in expansion, then <VAR>output</VAR> contains a descriptive
error message.
</DL>
</P><P>

<A NAME="IDX33"></A>
<DL>
<DT><U>Function:</U> char * <B>get_history_event</B> <I>(const char *string, int *cindex, int qchar)</I>
<DD>Returns the text of the history event beginning at <VAR>string</VAR> +
<VAR>*cindex</VAR>.  <VAR>*cindex</VAR> is modified to point to after the event
specifier.  At function entry, <VAR>cindex</VAR> points to the index into
<VAR>string</VAR> where the history event specification begins.  <VAR>qchar</VAR>
is a character that is allowed to end the event specification in addition
to the "normal" terminating characters.
</DL>
</P><P>

<A NAME="IDX34"></A>
<DL>
<DT><U>Function:</U> char ** <B>history_tokenize</B> <I>(const char *string)</I>
<DD>Return an array of tokens parsed out of <VAR>string</VAR>, much as the
shell might.  The tokens are split on the characters in the
<VAR>history_word_delimiters</VAR> variable,
and shell quoting conventions are obeyed as described below.
</DL>
</P><P>

<A NAME="IDX35"></A>
<DL>
<DT><U>Function:</U> char * <B>history_arg_extract</B> <I>(int first, int last, const char *string)</I>
<DD>Extract a string segment consisting of the <VAR>first</VAR> through <VAR>last</VAR>
arguments present in <VAR>string</VAR>.  Arguments are split using
<CODE>history_tokenize</CODE>.
</DL>
</P><P>

<A NAME="History Variables"></A>
<HR SIZE="6">
<A NAME="SEC17"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC16"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC18"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC18"> &lt;&lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC6"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC19"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H2> 2.4 History Variables </H2>
<!--docid::SEC17::-->
<P>

This section describes the externally-visible variables exported by
the GNU History Library.
</P><P>

<A NAME="IDX36"></A>
<DL>
<DT><U>Variable:</U> int <B>history_base</B>
<DD>The logical offset of the first entry in the history list.
</DL>
</P><P>

<A NAME="IDX37"></A>
<DL>
<DT><U>Variable:</U> int <B>history_length</B>
<DD>The number of entries currently stored in the history list.
</DL>
</P><P>

<A NAME="IDX38"></A>
<DL>
<DT><U>Variable:</U> int <B>history_max_entries</B>
<DD>The maximum number of history entries.  This must be changed using
<CODE>stifle_history()</CODE>.
</DL>
</P><P>

<A NAME="IDX39"></A>
<DL>
<DT><U>Variable:</U> int <B>history_write_timestamps</B>
<DD>If non-zero, timestamps are written to the history file, so they can be
preserved between sessions.  The default value is 0, meaning that
timestamps are not saved.
</P><P>

The current timestamp format uses the value of <VAR>history_comment_char</VAR>
to delimit timestamp entries in the history file.  If that variable does
not have a value (the default), timestamps will not be written.
</DL>
</P><P>

<A NAME="IDX40"></A>
<DL>
<DT><U>Variable:</U> char <B>history_expansion_char</B>
<DD>The character that introduces a history event.  The default is <SAMP>`!'</SAMP>.
Setting this to 0 inhibits history expansion.
</DL>
</P><P>

<A NAME="IDX41"></A>
<DL>
<DT><U>Variable:</U> char <B>history_subst_char</B>
<DD>The character that invokes word substitution if found at the start of
a line.  The default is <SAMP>`^'</SAMP>.
</DL>
</P><P>

<A NAME="IDX42"></A>
<DL>
<DT><U>Variable:</U> char <B>history_comment_char</B>
<DD>During tokenization, if this character is seen as the first character
of a word, then it and all subsequent characters up to a newline are
ignored, suppressing history expansion for the remainder of the line.
This is disabled by default.
</DL>
</P><P>

<A NAME="IDX43"></A>
<DL>
<DT><U>Variable:</U> char * <B>history_word_delimiters</B>
<DD>The characters that separate tokens for <CODE>history_tokenize()</CODE>.
The default value is <CODE>" \t\n()<>;&|"</CODE>.
</DL>
</P><P>

<A NAME="IDX44"></A>
<DL>
<DT><U>Variable:</U> char * <B>history_search_delimiter_chars</B>
<DD>The list of additional characters which can delimit a history search
string, in addition to space, TAB, <SAMP>`:'</SAMP> and <SAMP>`?'</SAMP> in the case of
a substring search.  The default is empty.
</DL>
</P><P>

<A NAME="IDX45"></A>
<DL>
<DT><U>Variable:</U> char * <B>history_no_expand_chars</B>
<DD>The list of characters which inhibit history expansion if found immediately
following <VAR>history_expansion_char</VAR>.  The default is space, tab, newline,
carriage return, and <SAMP>`='</SAMP>.
</DL>
</P><P>

<A NAME="IDX46"></A>
<DL>
<DT><U>Variable:</U> int <B>history_quotes_inhibit_expansion</B>
<DD>If non-zero, the history expansion code implements shell-like quoting:
single-quoted words are not scanned for the history expansion
character or the history comment character, and double-quoted words may
have history expansion performed, since single quotes are not special
within double quotes.
The default value is 0.
</DL>
</P><P>

<A NAME="IDX47"></A>
<DL>
<DT><U>Variable:</U> int <B>history_quoting_state</B>
<DD>An application may set this variable to indicate that the current line
being expanded is subject to existing quoting. If set to <SAMP>`''</SAMP>, the
history expansion function will assume that the line is single-quoted and
inhibit expansion until it reads an unquoted closing single quote; if set
to <SAMP>`"'</SAMP>, history expansion will assume the line is double quoted until
it reads an unquoted closing double quote. If set to zero, the default,
the history expansion function will assume the line is not quoted and
treat quote characters within the line as described above.
This is only effective if <VAR>history_quotes_inhibit_expansion</VAR> is set.
</DL>
</P><P>

<A NAME="IDX48"></A>
<DL>
<DT><U>Variable:</U> rl_linebuf_func_t * <B>history_inhibit_expansion_function</B>
<DD>This should be set to the address of a function that takes two arguments:
a <CODE>char *</CODE> (<VAR>string</VAR>)
and an <CODE>int</CODE> index into that string (<VAR>i</VAR>).
It should return a non-zero value if the history expansion starting at
<VAR>string[i]</VAR> should not be performed; zero if the expansion should
be done.
It is intended for use by applications like Bash that use the history
expansion character for additional purposes.
By default, this variable is set to <CODE>NULL</CODE>.
</DL>
</P><P>

<A NAME="History Programming Example"></A>
<HR SIZE="6">
<A NAME="SEC18"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC17"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC19"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[ &lt;&lt; ]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC6"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC19"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H2> 2.5 History Programming Example </H2>
<!--docid::SEC18::-->
<P>

The following program demonstrates simple use of the GNU History Library.
</P><P>

<TABLE><tr><td>&nbsp;</td><td class=smallexample><FONT SIZE=-1><pre>#include &#60;stdio.h&#62;
#include &#60;readline/history.h&#62;

main (argc, argv)
     int argc;
     char **argv;
{
  char line[1024], *t;
  int len, done = 0;

  line[0] = 0;

  using_history ();
  while (!done)
    {
      printf ("history$ ");
      fflush (stdout);
      t = fgets (line, sizeof (line) - 1, stdin);
      if (t &#38;&#38; *t)
        {
          len = strlen (t);
          if (t[len - 1] == '\n')
            t[len - 1] = '\0';
        }

      if (!t)
        strcpy (line, "quit");

      if (line[0])
        {
          char *expansion;
          int result;

          result = history_expand (line, &#38;expansion);
          if (result)
            fprintf (stderr, "%s\n", expansion);

          if (result &#60; 0 || result == 2)
            {
              free (expansion);
              continue;
            }

          add_history (expansion);
          strncpy (line, expansion, sizeof (line) - 1);
          free (expansion);
        }

      if (strcmp (line, "quit") == 0)
        done = 1;
      else if (strcmp (line, "save") == 0)
        write_history ("history_file");
      else if (strcmp (line, "read") == 0)
        read_history ("history_file");
      else if (strcmp (line, "list") == 0)
        {
          register HIST_ENTRY **the_list;
          register int i;

          the_list = history_list ();
          if (the_list)
            for (i = 0; the_list[i]; i++)
              printf ("%d: %s\n", i + history_base, the_list[i]-&#62;line);
        }
      else if (strncmp (line, "delete", 6) == 0)
        {
          int which;
          if ((sscanf (line + 6, "%d", &#38;which)) == 1)
            {
              HIST_ENTRY *entry = remove_history (which);
              if (!entry)
                fprintf (stderr, "No such entry %d\n", which);
              else
                {
                  free (entry-&#62;line);
                  free (entry);
                }
            }
          else
            {
              fprintf (stderr, "non-numeric arg given to `delete'\n");
            }
        }
    }
}
</FONT></pre></td></tr></table></P><P>

<A NAME="GNU Free Documentation License"></A>
<HR SIZE="6">
<A NAME="SEC19"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC18"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC6"> &lt;&lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H1> A. GNU Free Documentation License </H1>
<!--docid::SEC19::-->
<P>

<center>
 Version 1.3, 3 November 2008
</center>
</P><P>

<TABLE><tr><td>&nbsp;</td><td class=display><pre style="font-family: serif">Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
<A HREF="http://fsf.org/">http://fsf.org/</A>

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
</pre></td></tr></table></P><P>

<OL>
<LI>
PREAMBLE
<P>

The purpose of this License is to make a manual, textbook, or other
functional and useful document <EM>free</EM> in the sense of freedom: to
assure everyone the effective freedom to copy and redistribute it,
with or without modifying it, either commercially or noncommercially.
Secondarily, this License preserves for the author and publisher a way
to get credit for their work, while not being considered responsible
for modifications made by others.
</P><P>

This License is a kind of "copyleft", which means that derivative
works of the document must themselves be free in the same sense.  It
complements the GNU General Public License, which is a copyleft
license designed for free software.
</P><P>

We have designed this License in order to use it for manuals for free
software, because free software needs free documentation: a free
program should come with manuals providing the same freedoms that the
software does.  But this License is not limited to software manuals;
it can be used for any textual work, regardless of subject matter or
whether it is published as a printed book.  We recommend this License
principally for works whose purpose is instruction or reference.
</P><P>

<LI>
APPLICABILITY AND DEFINITIONS
<P>

This License applies to any manual or other work, in any medium, that
contains a notice placed by the copyright holder saying it can be
distributed under the terms of this License.  Such a notice grants a
world-wide, royalty-free license, unlimited in duration, to use that
work under the conditions stated herein.  The "Document", below,
refers to any such manual or work.  Any member of the public is a
licensee, and is addressed as "you".  You accept the license if you
copy, modify or distribute the work in a way requiring permission
under copyright law.
</P><P>

A "Modified Version" of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.
</P><P>

A "Secondary Section" is a named appendix or a front-matter section
of the Document that deals exclusively with the relationship of the
publishers or authors of the Document to the Document's overall
subject (or to related matters) and contains nothing that could fall
directly within that overall subject.  (Thus, if the Document is in
part a textbook of mathematics, a Secondary Section may not explain
any mathematics.)  The relationship could be a matter of historical
connection with the subject or with related matters, or of legal,
commercial, philosophical, ethical or political position regarding
them.
</P><P>

The "Invariant Sections" are certain Secondary Sections whose titles
are designated, as being those of Invariant Sections, in the notice
that says that the Document is released under this License.  If a
section does not fit the above definition of Secondary then it is not
allowed to be designated as Invariant.  The Document may contain zero
Invariant Sections.  If the Document does not identify any Invariant
Sections then there are none.
</P><P>

The "Cover Texts" are certain short passages of text that are listed,
as Front-Cover Texts or Back-Cover Texts, in the notice that says that
the Document is released under this License.  A Front-Cover Text may
be at most 5 words, and a Back-Cover Text may be at most 25 words.
</P><P>

A "Transparent" copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
straightforwardly with generic text editors or (for images composed of
pixels) generic paint programs or (for drawings) some widely available
drawing editor, and that is suitable for input to text formatters or
for automatic translation to a variety of formats suitable for input
to text formatters.  A copy made in an otherwise Transparent file
format whose markup, or absence of markup, has been arranged to thwart
or discourage subsequent modification by readers is not Transparent.
An image format is not Transparent if used for any substantial amount
of text.  A copy that is not "Transparent" is called "Opaque".
</P><P>

Examples of suitable formats for Transparent copies include plain
ASCII without markup, Texinfo input format, LaTeX input
format, <FONT SIZE="-1">SGML</FONT> or <FONT SIZE="-1">XML</FONT> using a publicly available
<FONT SIZE="-1">DTD</FONT>, and standard-conforming simple <FONT SIZE="-1">HTML</FONT>,
PostScript or <FONT SIZE="-1">PDF</FONT> designed for human modification.  Examples
of transparent image formats include <FONT SIZE="-1">PNG</FONT>, <FONT SIZE="-1">XCF</FONT> and
<FONT SIZE="-1">JPG</FONT>.  Opaque formats include proprietary formats that can be
read and edited only by proprietary word processors, <FONT SIZE="-1">SGML</FONT> or
<FONT SIZE="-1">XML</FONT> for which the <FONT SIZE="-1">DTD</FONT> and/or processing tools are
not generally available, and the machine-generated <FONT SIZE="-1">HTML</FONT>,
PostScript or <FONT SIZE="-1">PDF</FONT> produced by some word processors for
output purposes only.
</P><P>

The "Title Page" means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the material
this License requires to appear in the title page.  For works in
formats which do not have any title page as such, "Title Page" means
the text near the most prominent appearance of the work's title,
preceding the beginning of the body of the text.
</P><P>

The "publisher" means any person or entity that distributes copies
of the Document to the public.
</P><P>

A section "Entitled XYZ" means a named subunit of the Document whose
title either is precisely XYZ or contains XYZ in parentheses following
text that translates XYZ in another language.  (Here XYZ stands for a
specific section name mentioned below, such as "Acknowledgements",
"Dedications", "Endorsements", or "History".)  To "Preserve the Title"
of such a section when you modify the Document means that it remains a
section "Entitled XYZ" according to this definition.
</P><P>

The Document may include Warranty Disclaimers next to the notice which
states that this License applies to the Document.  These Warranty
Disclaimers are considered to be included by reference in this
License, but only as regards disclaiming warranties: any other
implication that these Warranty Disclaimers may have is void and has
no effect on the meaning of this License.
</P><P>

<LI>
VERBATIM COPYING
<P>

You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License applies
to the Document are reproduced in all copies, and that you add no other
conditions whatsoever to those of this License.  You may not use
technical measures to obstruct or control the reading or further
copying of the copies you make or distribute.  However, you may accept
compensation in exchange for copies.  If you distribute a large enough
number of copies you must also follow the conditions in section 3.
</P><P>

You may also lend copies, under the same conditions stated above, and
you may publicly display copies.
</P><P>

<LI>
COPYING IN QUANTITY
<P>

If you publish printed copies (or copies in media that commonly have
printed covers) of the Document, numbering more than 100, and the
Document's license notice requires Cover Texts, you must enclose the
copies in covers that carry, clearly and legibly, all these Cover
Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
the back cover.  Both covers must also clearly and legibly identify
you as the publisher of these copies.  The front cover must present
the full title with all words of the title equally prominent and
visible.  You may add other material on the covers in addition.
Copying with changes limited to the covers, as long as they preserve
the title of the Document and satisfy these conditions, can be treated
as verbatim copying in other respects.
</P><P>

If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
reasonably) on the actual cover, and continue the rest onto adjacent
pages.
</P><P>

If you publish or distribute Opaque copies of the Document numbering
more than 100, you must either include a machine-readable Transparent
copy along with each Opaque copy, or state in or with each Opaque copy
a computer-network location from which the general network-using
public has access to download using public-standard network protocols
a complete Transparent copy of the Document, free of added material.
If you use the latter option, you must take reasonably prudent steps,
when you begin distribution of Opaque copies in quantity, to ensure
that this Transparent copy will remain thus accessible at the stated
location until at least one year after the last time you distribute an
Opaque copy (directly or through your agents or retailers) of that
edition to the public.
</P><P>

It is requested, but not required, that you contact the authors of the
Document well before redistributing any large number of copies, to give
them a chance to provide you with an updated version of the Document.
</P><P>

<LI>
MODIFICATIONS
<P>

You may copy and distribute a Modified Version of the Document under
the conditions of sections 2 and 3 above, provided that you release
the Modified Version under precisely this License, with the Modified
Version filling the role of the Document, thus licensing distribution
and modification of the Modified Version to whoever possesses a copy
of it.  In addition, you must do these things in the Modified Version:
</P><P>

<OL>
<LI>
Use in the Title Page (and on the covers, if any) a title distinct
from that of the Document, and from those of previous versions
(which should, if there were any, be listed in the History section
of the Document).  You may use the same title as a previous version
if the original publisher of that version gives permission.
<P>

<LI>
List on the Title Page, as authors, one or more persons or entities
responsible for authorship of the modifications in the Modified
Version, together with at least five of the principal authors of the
Document (all of its principal authors, if it has fewer than five),
unless they release you from this requirement.
<P>

<LI>
State on the Title page the name of the publisher of the
Modified Version, as the publisher.
<P>

<LI>
Preserve all the copyright notices of the Document.
<P>

<LI>
Add an appropriate copyright notice for your modifications
adjacent to the other copyright notices.
<P>

<LI>
Include, immediately after the copyright notices, a license notice
giving the public permission to use the Modified Version under the
terms of this License, in the form shown in the Addendum below.
<P>

<LI>
Preserve in that license notice the full lists of Invariant Sections
and required Cover Texts given in the Document's license notice.
<P>

<LI>
Include an unaltered copy of this License.
<P>

<LI>
Preserve the section Entitled "History", Preserve its Title, and add
to it an item stating at least the title, year, new authors, and
publisher of the Modified Version as given on the Title Page.  If
there is no section Entitled "History" in the Document, create one
stating the title, year, authors, and publisher of the Document as
given on its Title Page, then add an item describing the Modified
Version as stated in the previous sentence.
<P>

<LI>
Preserve the network location, if any, given in the Document for
public access to a Transparent copy of the Document, and likewise
the network locations given in the Document for previous versions
it was based on.  These may be placed in the "History" section.
You may omit a network location for a work that was published at
least four years before the Document itself, or if the original
publisher of the version it refers to gives permission.
<P>

<LI>
For any section Entitled "Acknowledgements" or "Dedications", Preserve
the Title of the section, and preserve in the section all the
substance and tone of each of the contributor acknowledgements and/or
dedications given therein.
<P>

<LI>
Preserve all the Invariant Sections of the Document,
unaltered in their text and in their titles.  Section numbers
or the equivalent are not considered part of the section titles.
<P>

<LI>
Delete any section Entitled "Endorsements".  Such a section
may not be included in the Modified Version.
<P>

<LI>
Do not retitle any existing section to be Entitled "Endorsements" or
to conflict in title with any Invariant Section.
<P>

<LI>
Preserve any Warranty Disclaimers.
</OL>
<P>

If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no material
copied from the Document, you may at your option designate some or all
of these sections as invariant.  To do this, add their titles to the
list of Invariant Sections in the Modified Version's license notice.
These titles must be distinct from any other section titles.
</P><P>

You may add a section Entitled "Endorsements", provided it contains
nothing but endorsements of your Modified Version by various
parties--for example, statements of peer review or that the text has
been approved by an organization as the authoritative definition of a
standard.
</P><P>

You may add a passage of up to five words as a Front-Cover Text, and a
passage of up to 25 words as a Back-Cover Text, to the end of the list
of Cover Texts in the Modified Version.  Only one passage of
Front-Cover Text and one of Back-Cover Text may be added by (or
through arrangements made by) any one entity.  If the Document already
includes a cover text for the same cover, previously added by you or
by arrangement made by the same entity you are acting on behalf of,
you may not add another; but you may replace the old one, on explicit
permission from the previous publisher that added the old one.
</P><P>

The author(s) and publisher(s) of the Document do not by this License
give permission to use their names for publicity for or to assert or
imply endorsement of any Modified Version.
</P><P>

<LI>
COMBINING DOCUMENTS
<P>

You may combine the Document with other documents released under this
License, under the terms defined in section 4 above for modified
versions, provided that you include in the combination all of the
Invariant Sections of all of the original documents, unmodified, and
list them all as Invariant Sections of your combined work in its
license notice, and that you preserve all their Warranty Disclaimers.
</P><P>

The combined work need only contain one copy of this License, and
multiple identical Invariant Sections may be replaced with a single
copy.  If there are multiple Invariant Sections with the same name but
different contents, make the title of each such section unique by
adding at the end of it, in parentheses, the name of the original
author or publisher of that section if known, or else a unique number.
Make the same adjustment to the section titles in the list of
Invariant Sections in the license notice of the combined work.
</P><P>

In the combination, you must combine any sections Entitled "History"
in the various original documents, forming one section Entitled
"History"; likewise combine any sections Entitled "Acknowledgements",
and any sections Entitled "Dedications".  You must delete all
sections Entitled "Endorsements."
</P><P>

<LI>
COLLECTIONS OF DOCUMENTS
<P>

You may make a collection consisting of the Document and other documents
released under this License, and replace the individual copies of this
License in the various documents with a single copy that is included in
the collection, provided that you follow the rules of this License for
verbatim copying of each of the documents in all other respects.
</P><P>

You may extract a single document from such a collection, and distribute
it individually under this License, provided you insert a copy of this
License into the extracted document, and follow this License in all
other respects regarding verbatim copying of that document.
</P><P>

<LI>
AGGREGATION WITH INDEPENDENT WORKS
<P>

A compilation of the Document or its derivatives with other separate
and independent documents or works, in or on a volume of a storage or
distribution medium, is called an "aggregate" if the copyright
resulting from the compilation is not used to limit the legal rights
of the compilation's users beyond what the individual works permit.
When the Document is included in an aggregate, this License does not
apply to the other works in the aggregate which are not themselves
derivative works of the Document.
</P><P>

If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one half of
the entire aggregate, the Document's Cover Texts may be placed on
covers that bracket the Document within the aggregate, or the
electronic equivalent of covers if the Document is in electronic form.
Otherwise they must appear on printed covers that bracket the whole
aggregate.
</P><P>

<LI>
TRANSLATION
<P>

Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section 4.
Replacing Invariant Sections with translations requires special
permission from their copyright holders, but you may include
translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections.  You may include a
translation of this License, and all the license notices in the
Document, and any Warranty Disclaimers, provided that you also include
the original English version of this License and the original versions
of those notices and disclaimers.  In case of a disagreement between
the translation and the original version of this License or a notice
or disclaimer, the original version will prevail.
</P><P>

If a section in the Document is Entitled "Acknowledgements",
"Dedications", or "History", the requirement (section 4) to Preserve
its Title (section 1) will typically require changing the actual
title.
</P><P>

<LI>
TERMINATION
<P>

You may not copy, modify, sublicense, or distribute the Document
except as expressly provided under this License.  Any attempt
otherwise to copy, modify, sublicense, or distribute it is void, and
will automatically terminate your rights under this License.
</P><P>

However, if you cease all violation of this License, then your license
from a particular copyright holder is reinstated (a) provisionally,
unless and until the copyright holder explicitly and finally
terminates your license, and (b) permanently, if the copyright holder
fails to notify you of the violation by some reasonable means prior to
60 days after the cessation.
</P><P>

Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from that
copyright holder, and you cure the violation prior to 30 days after
your receipt of the notice.
</P><P>

Termination of your rights under this section does not terminate the
licenses of parties who have received copies or rights from you under
this License.  If your rights have been terminated and not permanently
reinstated, receipt of a copy of some or all of the same material does
not give you any rights to use it.
</P><P>

<LI>
FUTURE REVISIONS OF THIS LICENSE
<P>

The Free Software Foundation may publish new, revised versions
of the GNU Free Documentation License from time to time.  Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns.  See
<A HREF="http://www.gnu.org/copyleft/">http://www.gnu.org/copyleft/</A>.
</P><P>

Each version of the License is given a distinguishing version number.
If the Document specifies that a particular numbered version of this
License "or any later version" applies to it, you have the option of
following the terms and conditions either of that specified version or
of any later version that has been published (not as a draft) by the
Free Software Foundation.  If the Document does not specify a version
number of this License, you may choose any version ever published (not
as a draft) by the Free Software Foundation.  If the Document
specifies that a proxy can decide which future versions of this
License can be used, that proxy's public statement of acceptance of a
version permanently authorizes you to choose that version for the
Document.
</P><P>

<LI>
RELICENSING
<P>

"Massive Multiauthor Collaboration Site" (or "MMC Site") means any
World Wide Web server that publishes copyrightable works and also
provides prominent facilities for anybody to edit those works.  A
public wiki that anybody can edit is an example of such a server.  A
"Massive Multiauthor Collaboration" (or "MMC") contained in the
site means any set of copyrightable works thus published on the MMC
site.
</P><P>

"CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0
license published by Creative Commons Corporation, a not-for-profit
corporation with a principal place of business in San Francisco,
California, as well as future copyleft versions of that license
published by that same organization.
</P><P>

"Incorporate" means to publish or republish a Document, in whole or
in part, as part of another Document.
</P><P>

An MMC is "eligible for relicensing" if it is licensed under this
License, and if all works that were first published under this License
somewhere other than this MMC, and subsequently incorporated in whole
or in part into the MMC, (1) had no cover texts or invariant sections,
and (2) were thus incorporated prior to November 1, 2008.
</P><P>

The operator of an MMC Site may republish an MMC contained in the site
under CC-BY-SA on the same site at any time before August 1, 2009,
provided the MMC is eligible for relicensing.
</P><P>

</OL>
<P>

<A NAME="SEC20"></A>
<H2> ADDENDUM: How to use this License for your documents </H2>
<!--docid::SEC20::-->
<P>

To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and
license notices just after the title page:
</P><P>

<TABLE><tr><td>&nbsp;</td><td class=smallexample><FONT SIZE=-1><pre>  Copyright (C)  <VAR>year</VAR>  <VAR>your name</VAR>.
  Permission is granted to copy, distribute and/or modify this document
  under the terms of the GNU Free Documentation License, Version 1.3
  or any later version published by the Free Software Foundation;
  with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
  Texts.  A copy of the license is included in the section entitled ``GNU
  Free Documentation License''.
</FONT></pre></td></tr></table></P><P>

If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
replace the "with<small>...</small>Texts." line with this:
</P><P>

<TABLE><tr><td>&nbsp;</td><td class=smallexample><FONT SIZE=-1><pre>    with the Invariant Sections being <VAR>list their titles</VAR>, with
    the Front-Cover Texts being <VAR>list</VAR>, and with the Back-Cover Texts
    being <VAR>list</VAR>.
</FONT></pre></td></tr></table></P><P>

If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.
</P><P>

If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License,
to permit their use in free software.
</P><P>

<A NAME="Concept Index"></A>
<HR SIZE="6">
<A NAME="SEC21"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC19"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC22"> &gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC22"> &lt;&lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC22"> &gt;&gt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H1> B. Concept Index </H1>
<!--docid::SEC21::-->
<table><tr><th valign=top>Jump to: &nbsp; </th><td><A HREF="history.html#cp_A" style="text-decoration:none"><b>A</b></A>
 &nbsp; 
<A HREF="history.html#cp_E" style="text-decoration:none"><b>E</b></A>
 &nbsp; 
<A HREF="history.html#cp_H" style="text-decoration:none"><b>H</b></A>
 &nbsp; 
</td></tr></table><br><P></P>
<TABLE border=0>
<TR><TD></TD><TH ALIGN=LEFT>Index Entry</TH><TH ALIGN=LEFT> Section</TH></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="cp_A"></A>A</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX23">anchored search</A></TD><TD valign=top><A HREF="history.html#SEC14">2.3.5 Searching the History List</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="cp_E"></A>E</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#SEC3">event designators</A></TD><TD valign=top><A HREF="history.html#SEC3">1.1.1 Event Designators</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="cp_H"></A>H</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX1">history events</A></TD><TD valign=top><A HREF="history.html#SEC3">1.1.1 Event Designators</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#SEC2">history expansion</A></TD><TD valign=top><A HREF="history.html#SEC2">1.1 History Expansion</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#SEC14">History Searching</A></TD><TD valign=top><A HREF="history.html#SEC14">2.3.5 Searching the History List</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
</TABLE><P></P><table><tr><th valign=top>Jump to: &nbsp; </th><td><A HREF="history.html#cp_A" style="text-decoration:none"><b>A</b></A>
 &nbsp; 
<A HREF="history.html#cp_E" style="text-decoration:none"><b>E</b></A>
 &nbsp; 
<A HREF="history.html#cp_H" style="text-decoration:none"><b>H</b></A>
 &nbsp; 
</td></tr></table><br><P>

<A NAME="Function and Variable Index"></A>
<HR SIZE="6">
<A NAME="SEC22"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21"> &lt; </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[ &gt; ]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[ &lt;&lt; ]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[ &gt;&gt; ]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H1> C. Function and Variable Index </H1>
<!--docid::SEC22::-->
<table><tr><th valign=top>Jump to: &nbsp; </th><td><A HREF="history.html#vr_A" style="text-decoration:none"><b>A</b></A>
 &nbsp; 
<A HREF="history.html#vr_C" style="text-decoration:none"><b>C</b></A>
 &nbsp; 
<A HREF="history.html#vr_F" style="text-decoration:none"><b>F</b></A>
 &nbsp; 
<A HREF="history.html#vr_G" style="text-decoration:none"><b>G</b></A>
 &nbsp; 
<A HREF="history.html#vr_H" style="text-decoration:none"><b>H</b></A>
 &nbsp; 
<A HREF="history.html#vr_N" style="text-decoration:none"><b>N</b></A>
 &nbsp; 
<A HREF="history.html#vr_P" style="text-decoration:none"><b>P</b></A>
 &nbsp; 
<A HREF="history.html#vr_R" style="text-decoration:none"><b>R</b></A>
 &nbsp; 
<A HREF="history.html#vr_S" style="text-decoration:none"><b>S</b></A>
 &nbsp; 
<A HREF="history.html#vr_U" style="text-decoration:none"><b>U</b></A>
 &nbsp; 
<A HREF="history.html#vr_W" style="text-decoration:none"><b>W</b></A>
 &nbsp; 
</td></tr></table><br><P></P>
<TABLE border=0>
<TR><TD></TD><TH ALIGN=LEFT>Index Entry</TH><TH ALIGN=LEFT> Section</TH></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_A"></A>A</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX5"><CODE>add_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX6"><CODE>add_history_time</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX30"><CODE>append_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC15">2.3.6 Managing the History File</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_C"></A>C</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX10"><CODE>clear_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX16"><CODE>current_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC12">2.3.3 Information About the History List</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_F"></A>F</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX8"><CODE>free_history_entry</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_G"></A>G</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX33"><CODE>get_history_event</CODE></A></TD><TD valign=top><A HREF="history.html#SEC16">2.3.7 History Expansion</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_H"></A>H</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX35"><CODE>history_arg_extract</CODE></A></TD><TD valign=top><A HREF="history.html#SEC16">2.3.7 History Expansion</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX36"><CODE>history_base</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX42"><CODE>history_comment_char</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX32"><CODE>history_expand</CODE></A></TD><TD valign=top><A HREF="history.html#SEC16">2.3.7 History Expansion</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX40"><CODE>history_expansion_char</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX17"><CODE>history_get</CODE></A></TD><TD valign=top><A HREF="history.html#SEC12">2.3.3 Information About the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX3"><CODE>history_get_history_state</CODE></A></TD><TD valign=top><A HREF="history.html#SEC10">2.3.1 Initializing History and State Management</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX18"><CODE>history_get_time</CODE></A></TD><TD valign=top><A HREF="history.html#SEC12">2.3.3 Information About the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX48"><CODE>history_inhibit_expansion_function</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX13"><CODE>history_is_stifled</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX37"><CODE>history_length</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX14"><CODE>history_list</CODE></A></TD><TD valign=top><A HREF="history.html#SEC12">2.3.3 Information About the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX38"><CODE>history_max_entries</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX45"><CODE>history_no_expand_chars</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX46"><CODE>history_quotes_inhibit_expansion</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX47"><CODE>history_quoting_state</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX24"><CODE>history_search</CODE></A></TD><TD valign=top><A HREF="history.html#SEC14">2.3.5 Searching the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX44"><CODE>history_search_delimiter_chars</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX26"><CODE>history_search_pos</CODE></A></TD><TD valign=top><A HREF="history.html#SEC14">2.3.5 Searching the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX25"><CODE>history_search_prefix</CODE></A></TD><TD valign=top><A HREF="history.html#SEC14">2.3.5 Searching the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX4"><CODE>history_set_history_state</CODE></A></TD><TD valign=top><A HREF="history.html#SEC10">2.3.1 Initializing History and State Management</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX20"><CODE>history_set_pos</CODE></A></TD><TD valign=top><A HREF="history.html#SEC13">2.3.4 Moving Around the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX41"><CODE>history_subst_char</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX34"><CODE>history_tokenize</CODE></A></TD><TD valign=top><A HREF="history.html#SEC16">2.3.7 History Expansion</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX19"><CODE>history_total_bytes</CODE></A></TD><TD valign=top><A HREF="history.html#SEC12">2.3.3 Information About the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX31"><CODE>history_truncate_file</CODE></A></TD><TD valign=top><A HREF="history.html#SEC15">2.3.6 Managing the History File</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX43"><CODE>history_word_delimiters</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX39"><CODE>history_write_timestamps</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_N"></A>N</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX22"><CODE>next_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC13">2.3.4 Moving Around the History List</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_P"></A>P</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX21"><CODE>previous_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC13">2.3.4 Moving Around the History List</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_R"></A>R</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX27"><CODE>read_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC15">2.3.6 Managing the History File</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX28"><CODE>read_history_range</CODE></A></TD><TD valign=top><A HREF="history.html#SEC15">2.3.6 Managing the History File</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX7"><CODE>remove_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX9"><CODE>replace_history_entry</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_S"></A>S</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX11"><CODE>stifle_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_U"></A>U</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX12"><CODE>unstifle_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX2"><CODE>using_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC10">2.3.1 Initializing History and State Management</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_W"></A>W</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX15"><CODE>where_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC12">2.3.3 Information About the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX29"><CODE>write_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC15">2.3.6 Managing the History File</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
</TABLE><P></P><table><tr><th valign=top>Jump to: &nbsp; </th><td><A HREF="history.html#vr_A" style="text-decoration:none"><b>A</b></A>
 &nbsp; 
<A HREF="history.html#vr_C" style="text-decoration:none"><b>C</b></A>
 &nbsp; 
<A HREF="history.html#vr_F" style="text-decoration:none"><b>F</b></A>
 &nbsp; 
<A HREF="history.html#vr_G" style="text-decoration:none"><b>G</b></A>
 &nbsp; 
<A HREF="history.html#vr_H" style="text-decoration:none"><b>H</b></A>
 &nbsp; 
<A HREF="history.html#vr_N" style="text-decoration:none"><b>N</b></A>
 &nbsp; 
<A HREF="history.html#vr_P" style="text-decoration:none"><b>P</b></A>
 &nbsp; 
<A HREF="history.html#vr_R" style="text-decoration:none"><b>R</b></A>
 &nbsp; 
<A HREF="history.html#vr_S" style="text-decoration:none"><b>S</b></A>
 &nbsp; 
<A HREF="history.html#vr_U" style="text-decoration:none"><b>U</b></A>
 &nbsp; 
<A HREF="history.html#vr_W" style="text-decoration:none"><b>W</b></A>
 &nbsp; 
</td></tr></table><br><P>

<HR SIZE="6">
<A NAME="SEC_Contents"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H1>Table of Contents</H1>
<UL>
<A NAME="TOC1" HREF="history.html#SEC1">1. Using History Interactively</A>
<BR>
<UL>
<A NAME="TOC2" HREF="history.html#SEC2">1.1 History Expansion</A>
<BR>
<UL>
<A NAME="TOC3" HREF="history.html#SEC3">1.1.1 Event Designators</A>
<BR>
<A NAME="TOC4" HREF="history.html#SEC4">1.1.2 Word Designators</A>
<BR>
<A NAME="TOC5" HREF="history.html#SEC5">1.1.3 Modifiers</A>
<BR>
</UL>
</UL>
<A NAME="TOC6" HREF="history.html#SEC6">2. Programming with GNU History</A>
<BR>
<UL>
<A NAME="TOC7" HREF="history.html#SEC7">2.1 Introduction to History</A>
<BR>
<A NAME="TOC8" HREF="history.html#SEC8">2.2 History Storage</A>
<BR>
<A NAME="TOC9" HREF="history.html#SEC9">2.3 History Functions</A>
<BR>
<UL>
<A NAME="TOC10" HREF="history.html#SEC10">2.3.1 Initializing History and State Management</A>
<BR>
<A NAME="TOC11" HREF="history.html#SEC11">2.3.2 History List Management</A>
<BR>
<A NAME="TOC12" HREF="history.html#SEC12">2.3.3 Information About the History List</A>
<BR>
<A NAME="TOC13" HREF="history.html#SEC13">2.3.4 Moving Around the History List</A>
<BR>
<A NAME="TOC14" HREF="history.html#SEC14">2.3.5 Searching the History List</A>
<BR>
<A NAME="TOC15" HREF="history.html#SEC15">2.3.6 Managing the History File</A>
<BR>
<A NAME="TOC16" HREF="history.html#SEC16">2.3.7 History Expansion</A>
<BR>
</UL>
<A NAME="TOC17" HREF="history.html#SEC17">2.4 History Variables</A>
<BR>
<A NAME="TOC18" HREF="history.html#SEC18">2.5 History Programming Example</A>
<BR>
</UL>
<A NAME="TOC19" HREF="history.html#SEC19">A. GNU Free Documentation License</A>
<BR>
<A NAME="TOC21" HREF="history.html#SEC21">B. Concept Index</A>
<BR>
<A NAME="TOC22" HREF="history.html#SEC22">C. Function and Variable Index</A>
<BR>
</UL>
<HR SIZE=1>
<A NAME="SEC_OVERVIEW"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H1>Short Table of Contents</H1>
<BLOCKQUOTE>
<A NAME="TOC1" HREF="history.html#SEC1">1. Using History Interactively</A>
<BR>
<A NAME="TOC6" HREF="history.html#SEC6">2. Programming with GNU History</A>
<BR>
<A NAME="TOC19" HREF="history.html#SEC19">A. GNU Free Documentation License</A>
<BR>
<A NAME="TOC21" HREF="history.html#SEC21">B. Concept Index</A>
<BR>
<A NAME="TOC22" HREF="history.html#SEC22">C. Function and Variable Index</A>
<BR>

</BLOCKQUOTE>
<HR SIZE=1>
<A NAME="SEC_About"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC21">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H1>About this document</H1>
This document was generated by <I>Chet Ramey</I> on <I>October, 30  2020</I>
using <A HREF="http://www.mathematik.uni-kl.de/~obachman/Texi2html
"><I>texi2html</I></A>
<P></P>  
The buttons in the navigation panels have the following meaning:
<P></P>
<table border = "1">
<TR>
<TH> Button </TH>
<TH> Name </TH>
<TH> Go to </TH>
<TH> From 1.2.3 go to</TH>
</TR>
<TR>
<TD ALIGN="CENTER">
 [ &lt; ] </TD>
<TD ALIGN="CENTER">
Back
</TD>
<TD>
previous section in reading order
</TD>
<TD>
1.2.2
</TD>
</TR>
<TR>
<TD ALIGN="CENTER">
 [ &gt; ] </TD>
<TD ALIGN="CENTER">
Forward
</TD>
<TD>
next section in reading order
</TD>
<TD>
1.2.4
</TD>
</TR>
<TR>
<TD ALIGN="CENTER">
 [ &lt;&lt; ] </TD>
<TD ALIGN="CENTER">
FastBack
</TD>
<TD>
previous or up-and-previous section 
</TD>
<TD>
1.1
</TD>
</TR>
<TR>
<TD ALIGN="CENTER">
 [ Up ] </TD>
<TD ALIGN="CENTER">
Up
</TD>
<TD>
up section
</TD>
<TD>
1.2
</TD>
</TR>
<TR>
<TD ALIGN="CENTER">
 [ &gt;&gt; ] </TD>
<TD ALIGN="CENTER">
FastForward
</TD>
<TD>
next or up-and-next section
</TD>
<TD>
1.3
</TD>
</TR>
<TR>
<TD ALIGN="CENTER">
 [Top] </TD>
<TD ALIGN="CENTER">
Top
</TD>
<TD>
cover (top) of document
</TD>
<TD>
 &nbsp; 
</TD>
</TR>
<TR>
<TD ALIGN="CENTER">
 [Contents] </TD>
<TD ALIGN="CENTER">
Contents
</TD>
<TD>
table of contents
</TD>
<TD>
 &nbsp; 
</TD>
</TR>
<TR>
<TD ALIGN="CENTER">
 [Index] </TD>
<TD ALIGN="CENTER">
Index
</TD>
<TD>
concept index
</TD>
<TD>
 &nbsp; 
</TD>
</TR>
<TR>
<TD ALIGN="CENTER">
 [ ? ] </TD>
<TD ALIGN="CENTER">
About
</TD>
<TD>
this page
</TD>
<TD>
 &nbsp; 
</TD>
</TR>
</TABLE>
<P></P>
where the <STRONG> Example </STRONG> assumes that the current position 
is at <STRONG> Subsubsection One-Two-Three </STRONG> of a document of 
the following structure:
<UL>
<LI> 1. Section One  </LI>
<UL>
<LI>1.1 Subsection One-One</LI>
<UL>
<LI> ... </LI>
</UL>
<LI>1.2 Subsection One-Two</LI>
<UL>
<LI>1.2.1 Subsubsection One-Two-One
</LI><LI>1.2.2 Subsubsection One-Two-Two
</LI><LI>1.2.3 Subsubsection One-Two-Three &nbsp; &nbsp; <STRONG>
&lt;== Current Position </STRONG>
</LI><LI>1.2.4 Subsubsection One-Two-Four
</LI></UL>
<LI>1.3 Subsection One-Three</LI>
<UL>
<LI> ... </LI>
</UL>
<LI>1.4 Subsection One-Four</LI>
</UL>
</UL>

<HR SIZE=1>
<BR>  
<FONT SIZE="-1">
This document was generated
by <I>Chet Ramey</I> on <I>October, 30  2020</I>
using <A HREF="http://www.mathematik.uni-kl.de/~obachman/Texi2html
"><I>texi2html</I></A>

</BODY>
</HTML>