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-rw-r--r--examples/loadables/head.c170
1 files changed, 170 insertions, 0 deletions
diff --git a/examples/loadables/head.c b/examples/loadables/head.c
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+++ b/examples/loadables/head.c
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+/* head - copy first part of files. */
+
+/* See Makefile for compilation details. */
+
+/*
+ Copyright (C) 1999-2009 Free Software Foundation, Inc.
+
+ This file is part of GNU Bash.
+ Bash is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ Bash is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with Bash. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "config.h"
+
+#include "bashtypes.h"
+#include "posixstat.h"
+#include "filecntl.h"
+
+#if defined (HAVE_UNISTD_H)
+# include <unistd.h>
+#endif
+
+#include "bashansi.h"
+
+#include <stdio.h>
+#include <errno.h>
+#include "chartypes.h"
+
+#include "builtins.h"
+#include "shell.h"
+#include "bashgetopt.h"
+#include "common.h"
+
+#if !defined (errno)
+extern int errno;
+#endif
+
+static void
+munge_list (list)
+ WORD_LIST *list;
+{
+ WORD_LIST *l, *nl;
+ WORD_DESC *wd;
+ char *arg;
+
+ for (l = list; l; l = l->next)
+ {
+ arg = l->word->word;
+ if (arg[0] != '-' || arg[1] == '-' || (DIGIT(arg[1]) == 0))
+ return;
+ /* We have -[0-9]* */
+ wd = make_bare_word (arg+1);
+ nl = make_word_list (wd, l->next);
+ l->word->word[1] = 'n';
+ l->word->word[2] = '\0';
+ l->next = nl;
+ l = nl; /* skip over new argument */
+ }
+}
+
+static int
+file_head (fp, cnt)
+ FILE *fp;
+ int cnt;
+{
+ int ch;
+
+ while (cnt--)
+ {
+ while ((ch = getc (fp)) != EOF)
+ {
+ QUIT;
+ if (putchar (ch) == EOF)
+ {
+ builtin_error ("write error: %s", strerror (errno));
+ return EXECUTION_FAILURE;
+ }
+ QUIT;
+ if (ch == '\n')
+ break;
+ }
+ }
+ return (EXECUTION_SUCCESS);
+}
+
+int
+head_builtin (list)
+ WORD_LIST *list;
+{
+ int nline, opt, rval;
+ WORD_LIST *l;
+ FILE *fp;
+
+ char *t;
+
+ munge_list (list); /* change -num into -n num */
+
+ reset_internal_getopt ();
+ nline = 10;
+ while ((opt = internal_getopt (list, "n:")) != -1)
+ {
+ switch (opt)
+ {
+ case 'n':
+ nline = atoi (list_optarg);
+ if (nline <= 0)
+ {
+ builtin_error ("bad line count: %s", list_optarg);
+ return (EX_USAGE);
+ }
+ break;
+ CASE_HELPOPT;
+ default:
+ builtin_usage ();
+ return (EX_USAGE);
+ }
+ }
+ list = loptend;
+
+ if (list == 0)
+ return (file_head (stdin, nline));
+
+ for (rval = EXECUTION_SUCCESS, opt = 1, l = list; l; l = l->next)
+ {
+ fp = fopen (l->word->word, "r");
+ if (fp == NULL)
+ {
+ builtin_error ("%s: %s", l->word->word, strerror (errno));
+ continue;
+ }
+ if (list->next) /* more than one file */
+ {
+ printf ("%s==> %s <==\n", opt ? "" : "\n", l->word->word);
+ opt = 0;
+ }
+ QUIT;
+ rval = file_head (fp, nline);
+ fclose (fp);
+ }
+
+ return (rval);
+}
+
+char *head_doc[] = {
+ "Display lines from beginning of file.",
+ "",
+ "Copy the first N lines from the input files to the standard output.",
+ "N is supplied as an argument to the `-n' option. If N is not given,",
+ "the first ten lines are copied.",
+ (char *)NULL
+};
+
+struct builtin head_struct = {
+ "head", /* builtin name */
+ head_builtin, /* function implementing the builtin */
+ BUILTIN_ENABLED, /* initial flags for builtin */
+ head_doc, /* array of long documentation strings. */
+ "head [-n num] [file ...]", /* usage synopsis; becomes short_doc */
+ 0 /* reserved for internal use */
+};