Merging upstream version 1.9.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

8 files changed, 514 insertions, 495 deletions

diff --git a/doc/zcat.1 b/doc/zcat.1
index 443f813..29966ad 100644
--- a/doc/zcat.1
+++ b/doc/zcat.1
@@ -1,27 +1,29 @@
 .\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.46.1.
-.TH ZCAT "1" "January 2019" "zcat (zutils) 1.8" "User Commands"
+.TH ZCAT "1" "June 2020" "zcat (zutils) 1.9" "User Commands"
 .SH NAME
 zcat \- decompress and concatenate files to standard output
 .SH SYNOPSIS
 .B zcat
 [\fI\,options\/\fR] [\fI\,files\/\fR]
 .SH DESCRIPTION
-Zcat copies each given file to standard output. If any given file is
-compressed, its decompressed content is used. If a given file does not
-exist, and its name does not end with one of the known extensions, zcat
-tries the compressed file names corresponding to the formats supported.
+zcat copies each file argument to standard output in sequence. If any
+file given is compressed, its decompressed content is copied. If a file
+given does not exist, and its name does not end with one of the known
+extensions, zcat tries the compressed file names corresponding to the
+formats supported. If a file fails to decompress, zcat continues copying the
+rest of the files.
 .PP
 If a file is specified as '\-', data are read from standard input,
 decompressed if needed, and sent to standard output. Data read from
 standard input must be of the same type; all uncompressed or all in the
-same compression format.
+same compressed format.
 .PP
 If no files are specified, recursive searches examine the current
 working directory, and nonrecursive searches read standard input.
 .PP
-The formats supported are bzip2, gzip, lzip and xz.
+The formats supported are bzip2, gzip, lzip, and xz.
 .PP
-Exit status is 0 if no errors occurred, non\-zero otherwise.
+Exit status is 0 if no errors occurred, 1 otherwise.
 .SH OPTIONS
 .TP
 \fB\-h\fR, \fB\-\-help\fR
@@ -52,7 +54,7 @@ number all output lines
 don't read runtime configuration file
 .TP
 \fB\-O\fR, \fB\-\-force\-format=\fR<fmt>
-force given format (bz2, gz, lz, xz)
+force the format given (bz2, gz, lz, xz)
 .TP
 \fB\-q\fR, \fB\-\-quiet\fR
 suppress all messages
@@ -94,7 +96,7 @@ Report bugs to zutils\-bug@nongnu.org
 .br
 Zutils home page: http://www.nongnu.org/zutils/zutils.html
 .SH COPYRIGHT
-Copyright \(co 2019 Antonio Diaz Diaz.
+Copyright \(co 2020 Antonio Diaz Diaz.
 License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl.html>
 .br
 This is free software: you are free to change and redistribute it.
diff --git a/doc/zcmp.1 b/doc/zcmp.1
index e56b46f..b11d79b 100644
--- a/doc/zcmp.1
+++ b/doc/zcmp.1
@@ -1,31 +1,29 @@
 .\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.46.1.
-.TH ZCMP "1" "January 2019" "zcmp (zutils) 1.8" "User Commands"
+.TH ZCMP "1" "June 2020" "zcmp (zutils) 1.9" "User Commands"
 .SH NAME
 zcmp \- decompress and compare two files byte by byte
 .SH SYNOPSIS
 .B zcmp
 [\fI\,options\/\fR] \fI\,file1 \/\fR[\fI\,file2\/\fR]
 .SH DESCRIPTION
-Zcmp compares two files ('\-' means standard input), and if they differ,
-tells the first byte and line number where they differ. Bytes and lines
-are numbered starting with 1. If any given file is compressed, its
-decompressed content is used. Compressed files are decompressed on the
-fly; no temporary files are created.
+zcmp compares two files and, if they differ, writes to standard output the
+first byte and line number where they differ. Bytes and lines are numbered
+starting with 1. A hyphen '\-' used as a file argument means standard input.
+If any file given is compressed, its decompressed content is used. Compressed
+files are decompressed on the fly; no temporary files are created.
 .PP
-The formats supported are bzip2, gzip, lzip and xz.
+The formats supported are bzip2, gzip, lzip, and xz.
 .PP
-Zcmp compares file1 to file2. If file2 is omitted zcmp tries the
+zcmp compares file1 to file2. The standard input is used only if file1 or
+file2 refers to standard input. If file2 is omitted zcmp tries the
 following:
 .IP
-1. If file1 is compressed, compares its decompressed contents with
+\- If file1 is compressed, compares its decompressed contents with
 the corresponding uncompressed file (the name of file1 with the
 extension removed).
 .IP
-2. If file1 is uncompressed, compares it with the decompressed
+\- If file1 is uncompressed, compares it with the decompressed
 contents of file1.[lz|bz2|gz|xz] (the first one that is found).
-.IP
-3. If no suitable file is found, compares file1 with data read from
-standard input.
 .PP
 Exit status is 0 if inputs are identical, 1 if different, 2 if trouble.
 .SH OPTIONS
@@ -55,7 +53,7 @@ compare at most <n> bytes
 don't read runtime configuration file
 .TP
 \fB\-O\fR, \fB\-\-force\-format\fR=\fI\,[\/\fR<f1>][,<f2>]
-force given formats (bz2, gz, lz, xz)
+force the formats given (bz2, gz, lz, xz)
 .TP
 \fB\-q\fR, \fB\-\-quiet\fR
 suppress all messages
@@ -85,7 +83,7 @@ Report bugs to zutils\-bug@nongnu.org
 .br
 Zutils home page: http://www.nongnu.org/zutils/zutils.html
 .SH COPYRIGHT
-Copyright \(co 2019 Antonio Diaz Diaz.
+Copyright \(co 2020 Antonio Diaz Diaz.
 License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl.html>
 .br
 This is free software: you are free to change and redistribute it.
diff --git a/doc/zdiff.1 b/doc/zdiff.1
index 4edcf5e..7d8d387 100644
--- a/doc/zdiff.1
+++ b/doc/zdiff.1
@@ -1,33 +1,32 @@
 .\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.46.1.
-.TH ZDIFF "1" "January 2019" "zdiff (zutils) 1.8" "User Commands"
+.TH ZDIFF "1" "June 2020" "zdiff (zutils) 1.9" "User Commands"
 .SH NAME
 zdiff \- decompress and compare two files line by line
 .SH SYNOPSIS
 .B zdiff
 [\fI\,options\/\fR] \fI\,file1 \/\fR[\fI\,file2\/\fR]
 .SH DESCRIPTION
-Zdiff compares two files ('\-' means standard input), and if they
-differ, shows the differences line by line. If any given file is
-compressed, its decompressed content is used. Zdiff is a front end to
-the diff program and has the limitation that messages from diff refer to
-temporary filenames instead of those specified.
+zdiff compares two files and, if they differ, writes to standard output the
+differences line by line. A hyphen '\-' used as a file argument means standard
+input. If any file given is compressed, its decompressed content is used.
+zdiff is a front end to the program diff and has the limitation that messages
+from diff refer to temporary file names instead of those specified.
 .PP
-The formats supported are bzip2, gzip, lzip and xz.
+The formats supported are bzip2, gzip, lzip, and xz.
 .PP
-Zdiff compares file1 to file2. If file2 is omitted zdiff tries the
+zdiff compares file1 to file2. The standard input is used only if file1 or
+file2 refers to standard input. If file2 is omitted zdiff tries the
 following:
 .IP
-1. If file1 is compressed, compares its decompressed contents with
+\- If file1 is compressed, compares its decompressed contents with
 the corresponding uncompressed file (the name of file1 with the
 extension removed).
 .IP
-2. If file1 is uncompressed, compares it with the decompressed
+\- If file1 is uncompressed, compares it with the decompressed
 contents of file1.[lz|bz2|gz|xz] (the first one that is found).
-.IP
-3. If no suitable file is found, compares file1 with data read from
-standard input.
 .PP
 Exit status is 0 if inputs are identical, 1 if different, 2 if trouble.
+Some options only work if the diff program used supports them.
 .SH OPTIONS
 .TP
 \fB\-h\fR, \fB\-\-help\fR
@@ -67,7 +66,7 @@ process only the formats in <list>
 don't read runtime configuration file
 .TP
 \fB\-O\fR, \fB\-\-force\-format\fR=\fI\,[\/\fR<f1>][,<f2>]
-force given formats (bz2, gz, lz, xz)
+force the formats given (bz2, gz, lz, xz)
 .TP
 \fB\-p\fR, \fB\-\-show\-c\-function\fR
 show which C function each change is in
@@ -93,6 +92,12 @@ same as \fB\-u\fR but use <n> lines of context
 \fB\-w\fR, \fB\-\-ignore\-all\-space\fR
 ignore all white space
 .TP
+\fB\-W\fR, \fB\-\-width=\fR<n>
+output at most <n> print columns
+.TP
+\fB\-y\fR, \fB\-\-side\-by\-side\fR
+output in two columns
+.TP
 \fB\-\-bz2=\fR<command>
 set compressor and options for bzip2 format
 .TP
@@ -109,7 +114,7 @@ Report bugs to zutils\-bug@nongnu.org
 .br
 Zutils home page: http://www.nongnu.org/zutils/zutils.html
 .SH COPYRIGHT
-Copyright \(co 2019 Antonio Diaz Diaz.
+Copyright \(co 2020 Antonio Diaz Diaz.
 License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl.html>
 .br
 This is free software: you are free to change and redistribute it.
diff --git a/doc/zgrep.1 b/doc/zgrep.1
index 2418ef2..545aea2 100644
--- a/doc/zgrep.1
+++ b/doc/zgrep.1
@@ -1,29 +1,31 @@
 .\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.46.1.
-.TH ZGREP "1" "January 2019" "zgrep (zutils) 1.8" "User Commands"
+.TH ZGREP "1" "June 2020" "zgrep (zutils) 1.9" "User Commands"
 .SH NAME
 zgrep \- search compressed files for a regular expression
 .SH SYNOPSIS
 .B zgrep
 [\fI\,options\/\fR] \fI\,<pattern> \/\fR[\fI\,files\/\fR]
 .SH DESCRIPTION
-Zgrep is a front end to the grep program that allows transparent search
-on any combination of compressed and uncompressed files. If any given
-file is compressed, its decompressed content is used. If a given file
+zgrep is a front end to the program grep that allows transparent search
+on any combination of compressed and uncompressed files. If any file
+given is compressed, its decompressed content is used. If a file given
 does not exist, and its name does not end with one of the known
 extensions, zgrep tries the compressed file names corresponding to the
-formats supported.
+formats supported. If a file fails to decompress, zgrep continues
+searching the rest of the files.
 .PP
 If a file is specified as '\-', data are read from standard input,
 decompressed if needed, and fed to grep. Data read from standard input
 must be of the same type; all uncompressed or all in the same
-compression format.
+compressed format.
 .PP
 If no files are specified, recursive searches examine the current
 working directory, and nonrecursive searches read standard input.
 .PP
-The formats supported are bzip2, gzip, lzip and xz.
+The formats supported are bzip2, gzip, lzip, and xz.
 .PP
 Exit status is 0 if match, 1 if no match, 2 if trouble.
+Some options only work if the grep program used supports them.
 .SH OPTIONS
 .TP
 \fB\-\-help\fR
@@ -99,7 +101,7 @@ don't read runtime configuration file
 show only the part of a line matching <pattern>
 .TP
 \fB\-O\fR, \fB\-\-force\-format=\fR<fmt>
-force given format (bz2, gz, lz, xz)
+force the format given (bz2, gz, lz, xz)
 .TP
 \fB\-q\fR, \fB\-\-quiet\fR
 suppress all messages
@@ -144,7 +146,7 @@ Report bugs to zutils\-bug@nongnu.org
 .br
 Zutils home page: http://www.nongnu.org/zutils/zutils.html
 .SH COPYRIGHT
-Copyright \(co 2019 Antonio Diaz Diaz.
+Copyright \(co 2020 Antonio Diaz Diaz.
 License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl.html>
 .br
 This is free software: you are free to change and redistribute it.
diff --git a/doc/ztest.1 b/doc/ztest.1
index bffa73f..431e40c 100644
--- a/doc/ztest.1
+++ b/doc/ztest.1
@@ -1,20 +1,24 @@
 .\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.46.1.
-.TH ZTEST "1" "January 2019" "ztest (zutils) 1.8" "User Commands"
+.TH ZTEST "1" "June 2020" "ztest (zutils) 1.9" "User Commands"
 .SH NAME
 ztest \- verify the integrity of compressed files
 .SH SYNOPSIS
 .B ztest
 [\fI\,options\/\fR] [\fI\,files\/\fR]
 .SH DESCRIPTION
-Ztest verifies the integrity of the specified compressed files.
+ztest verifies the integrity of the compressed files specified.
 Uncompressed files are ignored. If a file is specified as '\-', the
 integrity of compressed data read from standard input is verified. Data
-read from standard input must be all in the same compression format.
+read from standard input must be all in the same compressed format. If
+a file fails to decompress, does not exist, can't be opened, or is a
+terminal, ztest continues verifying the rest of the files. A final
+diagnostic is shown at verbosity level 1 or higher if any file fails the
+test when testing multiple files.
 .PP
 If no files are specified, recursive searches examine the current
 working directory, and nonrecursive searches read standard input.
 .PP
-The formats supported are bzip2, gzip, lzip and xz.
+The formats supported are bzip2, gzip, lzip, and xz.
 .PP
 Note that error detection in the xz format is broken. First, some xz
 files lack integrity information. Second, not all xz decompressors can
@@ -41,7 +45,7 @@ process only the formats in <list>
 don't read runtime configuration file
 .TP
 \fB\-O\fR, \fB\-\-force\-format=\fR<fmt>
-force given format (bz2, gz, lz, xz)
+force the format given (bz2, gz, lz, xz)
 .TP
 \fB\-q\fR, \fB\-\-quiet\fR
 suppress all messages
@@ -71,7 +75,7 @@ Report bugs to zutils\-bug@nongnu.org
 .br
 Zutils home page: http://www.nongnu.org/zutils/zutils.html
 .SH COPYRIGHT
-Copyright \(co 2019 Antonio Diaz Diaz.
+Copyright \(co 2020 Antonio Diaz Diaz.
 License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl.html>
 .br
 This is free software: you are free to change and redistribute it.
diff --git a/doc/zupdate.1 b/doc/zupdate.1
index 955b8c5..afa65d3 100644
--- a/doc/zupdate.1
+++ b/doc/zupdate.1
@@ -1,12 +1,12 @@
 .\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.46.1.
-.TH ZUPDATE "1" "January 2019" "zupdate (zutils) 1.8" "User Commands"
+.TH ZUPDATE "1" "June 2020" "zupdate (zutils) 1.9" "User Commands"
 .SH NAME
 zupdate \- recompress bzip2, gzip, xz files to lzip format
 .SH SYNOPSIS
 .B zupdate
 [\fI\,options\/\fR] [\fI\,files\/\fR]
 .SH DESCRIPTION
-Zupdate recompresses files from bzip2, gzip, and xz formats to lzip
+zupdate recompresses files from bzip2, gzip, and xz formats to lzip
 format. Each original is compared with the new file and then deleted.
 Only regular files with standard file name extensions are recompressed,
 other files are ignored. Compressed files are decompressed and then
@@ -18,15 +18,18 @@ If no files are specified, recursive searches examine the current
 working directory, and nonrecursive searches do nothing.
 .PP
 If the lzip compressed version of a file already exists, the file is
-skipped unless the '\-\-force' option is given. In this case, if the
+skipped unless the option '\-\-force' is given. In this case, if the
 comparison with the existing lzip version fails, an error is returned
 and the original file is not deleted. The operation of zupdate is meant
-to be safe and not produce any data loss. Therefore, existing lzip
+to be safe and not cause any data loss. Therefore, existing lzip
 compressed files are never overwritten nor deleted.
 .PP
-Exit status is 0 if all the compressed files were successfully
-recompressed (if needed), compared and deleted (if requested). Non\-zero
-otherwise.
+The names of the original files must have one of the following extensions:
+\&'.bz2', '.gz', and '.xz' are recompressed to '.lz'.
+\&'.tbz', '.tbz2', '.tgz', and '.txz' are recompressed to '.tlz'.
+.PP
+Exit status is 0 if all the compressed files were successfully recompressed
+(if needed), compared, and deleted (if requested). Non\-zero otherwise.
 .SH OPTIONS
 .TP
 \fB\-h\fR, \fB\-\-help\fR
@@ -42,7 +45,7 @@ don't skip a file even if the .lz exists
 keep (don't delete) input files
 .TP
 \fB\-l\fR, \fB\-\-lzip\-verbose\fR
-pass a \fB\-v\fR option to the lzip compressor
+pass one option \fB\-v\fR to the lzip compressor
 .TP
 \fB\-M\fR, \fB\-\-format=\fR<list>
 process only the formats in <list>
@@ -81,7 +84,7 @@ Report bugs to zutils\-bug@nongnu.org
 .br
 Zutils home page: http://www.nongnu.org/zutils/zutils.html
 .SH COPYRIGHT
-Copyright \(co 2019 Antonio Diaz Diaz.
+Copyright \(co 2020 Antonio Diaz Diaz.
 License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl.html>
 .br
 This is free software: you are free to change and redistribute it.
diff --git a/doc/zutils.info b/doc/zutils.info
index bf99e2d..2de6d3b 100644
--- a/doc/zutils.info
+++ b/doc/zutils.info
@@ -1,5 +1,4 @@
-This is zutils.info, produced by makeinfo version 4.13+ from
-zutils.texi.
+This is zutils.info, produced by makeinfo version 4.13+ from zutils.texi.
 
 INFO-DIR-SECTION Data Compression
 START-INFO-DIR-ENTRY
@@ -12,7 +11,7 @@ File: zutils.info,  Node: Top,  Next: Introduction,  Up: (dir)
 Zutils Manual
 *************
 
-This manual is for Zutils (version 1.8, 1 January 2019).
+This manual is for Zutils (version 1.9, 27 June 2020).
 
 * Menu:
 
@@ -29,10 +28,10 @@ This manual is for Zutils (version 1.8, 1 January 2019).
 * Concept index::       Index of concepts
 
 
-   Copyright (C) 2009-2019 Antonio Diaz Diaz.
+   Copyright (C) 2009-2020 Antonio Diaz Diaz.
 
-   This manual is free documentation: you have unlimited permission to
-copy, distribute and modify it.
+   This manual is free documentation: you have unlimited permission to copy,
+distribute, and modify it.
 
 
 File: zutils.info,  Node: Introduction,  Next: Common options,  Prev: Top,  Up: Top
@@ -41,45 +40,45 @@ File: zutils.info,  Node: Introduction,  Next: Common options,  Prev: Top,  Up:
 **************
 
 Zutils is a collection of utilities able to process any combination of
-compressed and uncompressed files transparently. If any given file,
-including standard input, is compressed, its decompressed content is
-used. Compressed files are decompressed on the fly; no temporary files
-are created.
+compressed and uncompressed files transparently. If any file given,
+including standard input, is compressed, its decompressed content is used.
+Compressed files are decompressed on the fly; no temporary files are
+created.
 
-   These utilities are not wrapper scripts but safer and more efficient
-C++ programs. In particular the '--recursive' option is very efficient
-in those utilities supporting it.
+   These utilities are not wrapper scripts but safer and more efficient C++
+programs. In particular the option '--recursive' is very efficient in those
+utilities supporting it.
 
-The utilities provided are zcat, zcmp, zdiff, zgrep, ztest and zupdate.
-The formats supported are bzip2, gzip, lzip and xz.
-Zutils uses external compressors. The compressor to be used for each
-format is configurable at runtime.
+The utilities provided are zcat, zcmp, zdiff, zgrep, ztest, and zupdate.
+The formats supported are bzip2, gzip, lzip, and xz.
+Zutils uses external compressors. The compressor to be used for each format
+is configurable at runtime.
 
    zcat, zcmp, zdiff, and zgrep are improved replacements for the shell
-scripts provided by GNU gzip. ztest is unique to zutils. zupdate is
-similar to gzip's znew.
+scripts provided by GNU gzip. ztest is unique to zutils. zupdate is similar
+to gzip's znew.
 
-   NOTE: Bzip2 and lzip provide well-defined values of exit status,
-which makes them safe to use with zutils. Gzip and xz may return
-ambiguous warning values, making them less reliable back ends for
-zutils.  *Note compressor-requirements::.
+   NOTE: Bzip2 and lzip provide well-defined values of exit status, which
+makes them safe to use with zutils. Gzip and xz may return ambiguous warning
+values, making them less reliable back ends for zutils. *Note
+compressor-requirements::.
 
-   FORMAT NOTE 1: The '--format' option allows the processing of a
-subset of formats in recursive mode and when trying compressed file
-names: 'zgrep foo -r --format=bz2,lz somedir somefile.tar'.
+   FORMAT NOTE 1: The option '--format' allows the processing of a subset
+of formats in recursive mode and when trying compressed file names:
+'zgrep foo -r --format=bz2,lz somedir somefile.tar'.
 
-   FORMAT NOTE 2: If the '--force-format' option is given, the files
-are passed to the corresponding decompressor without verifying their
-format, allowing for example the processing of compress'd (.Z) files
-with gzip: 'zcmp --force-format=gz file.Z file.lz'.
+   FORMAT NOTE 2: If the option '--force-format' is given, the files are
+passed to the corresponding decompressor without verifying their format,
+allowing for example the processing of compress'd (.Z) files with gzip:
+'zcmp --force-format=gz file.Z file.lz'.
 
-   LANGUAGE NOTE: Uncompressed = not compressed = plain data; it may
-never have been compressed. Decompressed is used to refer to data which
-have undergone the process of decompression.
+   LANGUAGE NOTE: Uncompressed = not compressed = plain data; it may never
+have been compressed. Decompressed is used to refer to data which have
+undergone the process of decompression.
 
 
-   Numbers given as arguments to options (positions, sizes) may be
-followed by a multiplier and an optional 'B' for "byte".
+   Numbers given as arguments to options (positions, sizes) may be followed
+by a multiplier and an optional 'B' for "byte".
 
    Table of SI and binary prefixes (unit multipliers):
 
@@ -99,9 +98,9 @@ File: zutils.info,  Node: Common options,  Next: The zutilsrc file,  Prev: Intro
 2 Common options
 ****************
 
-The following options are available in all the utilities. Rather than
-writing identical descriptions for each of the programs, they are
-described here.
+The following options: are available in all the utilities. Rather than
+writing identical descriptions for each of the programs, they are described
+here. *Note Argument syntax: (arg_parser)Argument syntax.
 
 '-h'
 '--help'
@@ -110,19 +109,19 @@ described here.
 
 '-V'
 '--version'
-     Print the version number on the standard output and exit.  This
-     version number should be included in all bug reports.
+     Print the version number on the standard output and exit. This version
+     number should be included in all bug reports.
 
 '-M FORMAT_LIST'
 '--format=FORMAT_LIST'
-     Process only the formats listed in the comma-separated
-     FORMAT_LIST. Valid formats are 'bz2', 'gz', 'lz', 'xz' and 'un'
-     for 'uncompressed', meaning "any file name without a known
-     extension". This option excludes files based on extension, instead
-     of format, because it is more efficient. The exclusion only
-     applies to names generated automatically (for example when adding
-     extensions to a file name or when operating recursively on
-     directories). Files given in the command line are always processed.
+     Process only the formats listed in the comma-separated FORMAT_LIST.
+     Valid formats are 'bz2', 'gz', 'lz', 'xz', and 'un' for
+     'uncompressed', meaning "any file name without a known extension".
+     This option excludes files based on extension, instead of format,
+     because it is more efficient. The exclusion only applies to names
+     generated automatically (for example when adding extensions to a file
+     name or when operating recursively on directories). Files given in the
+     command line are always processed.
 
      Each format in FORMAT_LIST enables file names with the following
      extensions:
@@ -141,17 +140,20 @@ described here.
 '--gz=COMMAND'
 '--lz=COMMAND'
 '--xz=COMMAND'
-     Set program (may include arguments) to be used as (de)compressor
-     for the given format. The name of the program can't begin with
-     '-'. These options override the values set in 'zutilsrc'. The
-     compression program used must meet three requirements:
+     Set program to be used as (de)compressor for the corresponding format.
+     COMMAND may include arguments. For example '--lz='plzip --threads=2''.
+     The program set with '--lz' is used for both compression and
+     decompression. The other three are used only for decompression. The
+     name of the program can't begin with '-'. These options override the
+     values set in 'zutilsrc'. The compression program used must meet three
+     requirements:
 
-       1. When called with the '-d' option, it must read compressed
-          data from the standard input and produce decompressed data on
-          the standard output.
+       1. When called with the option '-d', it must read compressed data
+          from the standard input and produce decompressed data on the
+          standard output.
 
-       2. If the '-q' option is passed to zutils, the compression
-          program must also accept it.
+       2. If the option '-q' is passed to zutils, the compression program
+          must also accept it.
 
        3. It must return 0 if no errors occurred, and a non-zero value
           otherwise.
@@ -164,23 +166,23 @@ File: zutils.info,  Node: The zutilsrc file,  Next: Zcat,  Prev: Common options,
 *******************
 
 'zutilsrc' is the runtime configuration file for zutils. In it you may
-define the compressor name and options to be used for each format.  The
-'zutilsrc' file is optional; you don't need to install it in order to
-run zutils.
+define the compressor name and options to be used for each format. The
+'zutilsrc' file is optional; you don't need to install it in order to run
+zutils.
 
-   The compressors specified in the command line override those
-specified in the 'zutilsrc' file.
+   The compressors specified in the command line override those specified
+in the 'zutilsrc' file.
 
    You may copy the system 'zutilsrc' file '${sysconfdir}/zutilsrc' to
-'$HOME/.zutilsrc' and customize these options as you like. The file
-syntax is fairly obvious (and there are further instructions in it):
+'$HOME/.zutilsrc' and customize these options as you like. The file syntax
+is fairly obvious (and there are further instructions in it):
 
   1. Any line beginning with '#' is a comment line.
 
-  2. Each non-comment line defines the command to be used for the given
-     format, with the syntax:
+  2. Each non-comment line defines the command to be used for the
+     corresponding format, with the syntax:
           <format> = <compressor> [options]
-     where <format> is one of 'bz2', 'gz', 'lz' or 'xz'.
+     where <format> is one of 'bz2', 'gz', 'lz', or 'xz'.
 
 
 File: zutils.info,  Node: Zcat,  Next: Zcmp,  Prev: The zutilsrc file,  Up: Top
@@ -188,26 +190,26 @@ File: zutils.info,  Node: Zcat,  Next: Zcmp,  Prev: The zutilsrc file,  Up: Top
 4 Zcat
 ******
 
-zcat copies each given file to standard output. If any given file is
-compressed, its decompressed content is used. If a given file does not
-exist, and its name does not end with one of the known extensions, zcat
-tries the compressed file names corresponding to the formats supported.
-If a file fails to decompress, zcat continues copying the rest of the
-files.
+zcat copies each FILE argument to standard output in sequence. If any file
+given is compressed, its decompressed content is copied. If a file given
+does not exist, and its name does not end with one of the known extensions,
+zcat tries the compressed file names corresponding to the formats
+supported. If a file fails to decompress, zcat continues copying the rest
+of the files.
 
    If a file is specified as '-', data are read from standard input,
 decompressed if needed, and sent to standard output. Data read from
 standard input must be of the same type; all uncompressed or all in the
-same compression format.
+same compressed format.
 
-   If no files are specified, recursive searches examine the current
-working directory, and nonrecursive searches read standard input.
+   If no files are specified, recursive searches examine the current working
+directory, and nonrecursive searches read standard input.
 
    The format for running zcat is:
 
      zcat [OPTIONS] [FILES]
 
-Exit status is 0 if no errors occurred, non-zero otherwise.
+Exit status is 0 if no errors occurred, 1 otherwise.
 
    zcat supports the following options:
 
@@ -217,8 +219,8 @@ Exit status is 0 if no errors occurred, non-zero otherwise.
 
 '-b'
 '--number-nonblank'
-     Number all nonblank output lines, starting with 1. The line count
-     is unlimited.
+     Number all nonblank output lines, starting with 1. The line count is
+     unlimited.
 
 '-e'
      Equivalent to '-vE'.
@@ -229,16 +231,14 @@ Exit status is 0 if no errors occurred, non-zero otherwise.
 
 '-n'
 '--number'
-     Number all output lines, starting with 1. The line count is
-     unlimited.
+     Number all output lines, starting with 1. The line count is unlimited.
 
 '-O FORMAT'
 '--force-format=FORMAT'
-     Force the given compression format. Valid values for FORMAT are
-     'bz2', 'gz', 'lz' and 'xz'. If this option is used, the files are
-     passed to the corresponding decompressor without verifying their
-     format, and the exact file name must be given. Other names won't
-     be tried.
+     Force the compressed format given. Valid values for FORMAT are 'bz2',
+     'gz', 'lz', and 'xz'. If this option is used, the files are passed to
+     the corresponding decompressor without verifying their format, and the
+     exact file name must be given. Other names won't be tried.
 
 '-q'
 '--quiet'
@@ -247,8 +247,8 @@ Exit status is 0 if no errors occurred, non-zero otherwise.
 '-r'
 '--recursive'
      For each directory operand, read and process all files in that
-     directory, recursively. Follow symbolic links in the command line,
-     but skip symlinks that are encountered recursively.
+     directory, recursively. Follow symbolic links given in the command
+     line, but skip symbolic links that are encountered recursively.
 
 '-R'
 '--dereference-recursive'
@@ -282,28 +282,27 @@ File: zutils.info,  Node: Zcmp,  Next: Zdiff,  Prev: Zcat,  Up: Top
 5 Zcmp
 ******
 
-zcmp compares two files ('-' means standard input), and if they differ,
-tells the first byte and line number where they differ. Bytes and lines
-are numbered starting with 1. If any given file is compressed, its
-decompressed content is used. Compressed files are decompressed on the
-fly; no temporary files are created.
+zcmp compares two files and, if they differ, writes to standard output the
+first byte and line number where they differ. Bytes and lines are numbered
+starting with 1. A hyphen '-' used as a FILE argument means standard input.
+If any file given is compressed, its decompressed content is used.
+Compressed files are decompressed on the fly; no temporary files are
+created.
 
    The format for running zcmp is:
 
      zcmp [OPTIONS] FILE1 [FILE2]
 
-This compares FILE1 to FILE2. If FILE2 is omitted zcmp tries the
+This compares FILE1 to FILE2. The standard input is used only if FILE1 or
+FILE2 refers to standard input. If FILE2 is omitted zcmp tries the
 following:
 
-  1. If FILE1 is compressed, compares its decompressed contents with
-     the corresponding uncompressed file (the name of FILE1 with the
-     extension removed).
+   - If FILE1 is compressed, compares its decompressed contents with the
+     corresponding uncompressed file (the name of FILE1 with the extension
+     removed).
 
-  2. If FILE1 is uncompressed, compares it with the decompressed
-     contents of FILE1.[lz|bz2|gz|xz] (the first one that is found).
-
-  3. If no suitable file is found, compares FILE1 with data read from
-     standard input.
+   - If FILE1 is uncompressed, compares it with the decompressed contents
+     of FILE1.[lz|bz2|gz|xz] (the first one that is found).
 
 An exit status of 0 means no differences were found, 1 means some
 differences were found, and 2 means trouble.
@@ -312,17 +311,16 @@ differences were found, and 2 means trouble.
 
 '-b'
 '--print-bytes'
-     Print the differing bytes. Print control bytes as a '^' followed by
-     a letter, and precede bytes larger than 127 with 'M-' (which stands
-     for "meta").
+     Print the differing bytes. Print control bytes as a '^' followed by a
+     letter, and precede bytes larger than 127 with 'M-' (which stands for
+     "meta").
 
 '-i SIZE'
 '--ignore-initial=SIZE'
      Ignore any differences in the first SIZE bytes of the input files.
-     Treat files with fewer than SIZE bytes as if they were empty. If
-     SIZE is in the form 'SIZE1:SIZE2', ignore the first SIZE1 bytes of
-     the first input file and the first SIZE2 bytes of the second input
-     file.
+     Treat files with fewer than SIZE bytes as if they were empty. If SIZE
+     is in the form 'SIZE1:SIZE2', ignore the first SIZE1 bytes of the
+     first input file and the first SIZE2 bytes of the second input file.
 
 '-l'
 '-v'
@@ -337,20 +335,20 @@ differences were found, and 2 means trouble.
 
 '-O [FORMAT1][,FORMAT2]'
 '--force-format=[FORMAT1][,FORMAT2]'
-     Force the given compression formats. Any of FORMAT1 or FORMAT2 may
-     be omitted and the corresponding format will be automatically
-     detected. Valid values for FORMAT are 'bz2', 'gz', 'lz' and 'xz'.
-     If at least one format is specified with this option, the file is
-     passed to the corresponding decompressor without verifying its
-     format, and the exact file names of both FILE1 and FILE2 must be
-     given. Other names won't be tried.
+     Force the compressed formats given. Any of FORMAT1 or FORMAT2 may be
+     omitted and the corresponding format will be automatically detected.
+     Valid values for FORMAT are 'bz2', 'gz', 'lz', and 'xz'. If at least
+     one format is specified with this option, the file is passed to the
+     corresponding decompressor without verifying its format, and the exact
+     file names of both FILE1 and FILE2 must be given. Other names won't be
+     tried.
 
 '-q'
 '-s'
 '--quiet'
 '--silent'
-     Don't print anything; only return an exit status indicating
-     whether the files differ.
+     Don't print anything; only return an exit status indicating whether the
+     files differ.
 
 
 
@@ -359,34 +357,33 @@ File: zutils.info,  Node: Zdiff,  Next: Zgrep,  Prev: Zcmp,  Up: Top
 6 Zdiff
 *******
 
-zdiff compares two files ('-' means standard input), and if they
-differ, shows the differences line by line. If any given file is
-compressed, its decompressed content is used. zdiff is a front end to
-the diff program and has the limitation that messages from diff refer to
-temporary file names instead of those specified.
+zdiff compares two files and, if they differ, writes to standard output the
+differences line by line. A hyphen '-' used as a FILE argument means
+standard input. If any file given is compressed, its decompressed content
+is used. zdiff is a front end to the program diff and has the limitation
+that messages from diff refer to temporary file names instead of those
+specified.
 
    The format for running zdiff is:
 
      zdiff [OPTIONS] FILE1 [FILE2]
 
-This compares FILE1 to FILE2. If FILE2 is omitted zdiff tries the
+This compares FILE1 to FILE2. The standard input is used only if FILE1 or
+FILE2 refers to standard input. If FILE2 is omitted zdiff tries the
 following:
 
-  1. If FILE1 is compressed, compares its decompressed contents with
-     the corresponding uncompressed file (the name of FILE1 with the
-     extension removed).
+   - If FILE1 is compressed, compares its decompressed contents with the
+     corresponding uncompressed file (the name of FILE1 with the extension
+     removed).
 
-  2. If FILE1 is uncompressed, compares it with the decompressed
-     contents of FILE1.[lz|bz2|gz|xz] (the first one that is found).
-
-  3. If no suitable file is found, compares FILE1 with data read from
-     standard input.
+   - If FILE1 is uncompressed, compares it with the decompressed contents
+     of FILE1.[lz|bz2|gz|xz] (the first one that is found).
 
 An exit status of 0 means no differences were found, 1 means some
 differences were found, and 2 means trouble.
 
-   zdiff supports the following options (some options only work if the
-diff program used supports them):
+   zdiff supports the following options (some options only work if the diff
+program used supports them):
 
 '-a'
 '--text'
@@ -421,13 +418,13 @@ diff program used supports them):
 
 '-O [FORMAT1][,FORMAT2]'
 '--force-format=[FORMAT1][,FORMAT2]'
-     Force the given compression formats. Any of FORMAT1 or FORMAT2 may
-     be omitted and the corresponding format will be automatically
-     detected. Valid values for FORMAT are 'bz2', 'gz', 'lz' and 'xz'.
-     If at least one format is specified with this option, the file is
-     passed to the corresponding decompressor without verifying its
-     format, and the exact file names of both FILE1 and FILE2 must be
-     given. Other names won't be tried.
+     Force the compressed formats given. Any of FORMAT1 or FORMAT2 may be
+     omitted and the corresponding format will be automatically detected.
+     Valid values for FORMAT are 'bz2', 'gz', 'lz', and 'xz'. If at least
+     one format is specified with this option, the file is passed to the
+     corresponding decompressor without verifying its format, and the exact
+     file names of both FILE1 and FILE2 must be given. Other names won't be
+     tried.
 
 '-p'
 '--show-c-function'
@@ -467,31 +464,29 @@ File: zutils.info,  Node: Zgrep,  Next: Ztest,  Prev: Zdiff,  Up: Top
 7 Zgrep
 *******
 
-zgrep is a front end to the grep program that allows transparent search
-on any combination of compressed and uncompressed files. If any given
-file is compressed, its decompressed content is used. If a given file
-does not exist, and its name does not end with one of the known
-extensions, zgrep tries the compressed file names corresponding to the
-formats supported. If a file fails to decompress, zgrep continues
-searching the rest of the files.
+zgrep is a front end to the program grep that allows transparent search on
+any combination of compressed and uncompressed files. If any file given is
+compressed, its decompressed content is used. If a file given does not
+exist, and its name does not end with one of the known extensions, zgrep
+tries the compressed file names corresponding to the formats supported. If
+a file fails to decompress, zgrep continues searching the rest of the files.
 
    If a file is specified as '-', data are read from standard input,
-decompressed if needed, and fed to grep. Data read from standard input
-must be of the same type; all uncompressed or all in the same
-compression format.
+decompressed if needed, and fed to grep. Data read from standard input must
+be of the same type; all uncompressed or all in the same compressed format.
 
-   If no files are specified, recursive searches examine the current
-working directory, and nonrecursive searches read standard input.
+   If no files are specified, recursive searches examine the current working
+directory, and nonrecursive searches read standard input.
 
    The format for running zgrep is:
 
      zgrep [OPTIONS] PATTERN [FILES]
 
-An exit status of 0 means at least one match was found, 1 means no
-matches were found, and 2 means trouble.
+An exit status of 0 means at least one match was found, 1 means no matches
+were found, and 2 means trouble.
 
-   zgrep supports the following options (some options only work if the
-grep program used supports them):
+   zgrep supports the following options (some options only work if the grep
+program used supports them):
 
 '-a'
 '--text'
@@ -518,7 +513,7 @@ grep program used supports them):
      Print N lines of output context.
 
 '--color[=WHEN]'
-     Show matched strings in color. WHEN is 'never', 'always' or 'auto'.
+     Show matched strings in color. WHEN is 'never', 'always', or 'auto'.
 
 '-e PATTERN'
 '--regexp=PATTERN'
@@ -531,9 +526,9 @@ grep program used supports them):
 '-f FILE'
 '--file=FILE'
      Obtain patterns from FILE, one per line.
-     When searching in several files at once, command substitution can
-     be used with '-e' to read FILE only once, for example if FILE is
-     not a regular file: 'zgrep -e "$(cat FILE)" file1.lz file2.gz'
+     When searching in several files at once, command substitution can be
+     used with '-e' to read FILE only once, for example if FILE is not a
+     regular file: 'zgrep -e "$(cat FILE)" file1.lz file2.gz'
 
 '-F'
 '--fixed-strings'
@@ -541,8 +536,8 @@ grep program used supports them):
 
 '-h'
 '--no-filename'
-     Suppress the prefixing of file names on output when multiple files
-     are searched.
+     Suppress the prefixing of file names on output when multiple files are
+     searched.
 
 '-H'
 '--with-filename'
@@ -577,22 +572,21 @@ grep program used supports them):
 
 '-O FORMAT'
 '--force-format=FORMAT'
-     Force the given compression format. Valid values for FORMAT are
-     'bz2', 'gz', 'lz' and 'xz'. If this option is used, the files are
-     passed to the corresponding decompressor without verifying their
-     format, and the exact file name must be given. Other names won't
-     be tried.
+     Force the compressed format given. Valid values for FORMAT are 'bz2',
+     'gz', 'lz', and 'xz'. If this option is used, the files are passed to
+     the corresponding decompressor without verifying their format, and the
+     exact file name must be given. Other names won't be tried.
 
 '-q'
 '--quiet'
-     Suppress all messages. Exit immediately with zero status if any
-     match is found, even if an error was detected.
+     Suppress all messages. Exit immediately with zero status if any match
+     is found, even if an error was detected.
 
 '-r'
 '--recursive'
      For each directory operand, read and process all files in that
-     directory, recursively. Follow symbolic links in the command line,
-     but skip symlinks that are encountered recursively.
+     directory, recursively. Follow symbolic links given in the command
+     line, but skip symbolic links that are encountered recursively.
 
 '-R'
 '--dereference-recursive'
@@ -625,42 +619,43 @@ File: zutils.info,  Node: Ztest,  Next: Zupdate,  Prev: Zgrep,  Up: Top
 8 Ztest
 *******
 
-ztest verifies the integrity of the specified compressed files.
+ztest verifies the integrity of the compressed files specified.
 Uncompressed files are ignored. If a file is specified as '-', the
 integrity of compressed data read from standard input is verified. Data
-read from standard input must be all in the same compression format. If
-a file fails to decompress, ztest continues verifying the rest of the
-files.
+read from standard input must be all in the same compressed format. If a
+file fails to decompress, does not exist, can't be opened, or is a
+terminal, ztest continues verifying the rest of the files. A final
+diagnostic is shown at verbosity level 1 or higher if any file fails the
+test when testing multiple files.
 
-   If no files are specified, recursive searches examine the current
-working directory, and nonrecursive searches read standard input.
+   If no files are specified, recursive searches examine the current working
+directory, and nonrecursive searches read standard input.
 
    Note that error detection in the xz format is broken. First, some xz
 files lack integrity information. Second, not all xz decompressors can
-verify the integrity of all xz files. Third, section 2.1.1.2 'Stream
-Flags' of the xz format specification allows xz decompressors to
-produce garbage output without issuing any warning. Therefore, xz files
-can't always be verified as reliably as files in the other formats can.
+verify the integrity of all xz files. Third, section 2.1.1.2 'Stream Flags'
+of the xz format specification allows xz decompressors to produce garbage
+output without issuing any warning. Therefore, xz files can't always be
+verified as reliably as files in the other formats can.
 
    The format for running ztest is:
 
      ztest [OPTIONS] [FILES]
 
-The exit status is 0 if all compressed files verify OK, 1 if
-environmental problems (file not found, invalid flags, I/O errors, etc),
-2 if any compressed file is corrupt or invalid.
+The exit status is 0 if all compressed files verify OK, 1 if environmental
+problems (file not found, invalid flags, I/O errors, etc), 2 if any
+compressed file is corrupt or invalid.
 
    ztest supports the following options:
 
 '-O FORMAT'
 '--force-format=FORMAT'
-     Force the given compression format. Valid values for FORMAT are
-     'bz2', 'gz', 'lz' and 'xz'. If this option is used, the files are
-     passed to the corresponding decompressor without verifying their
-     format, and any files in a format that the decompressor can't
-     understand will fail. For example, '--force-format=gz' can test
-     gzipped (.gz) and compress'd (.Z) files if the compressor used is
-     GNU gzip.
+     Force the compressed format given. Valid values for FORMAT are 'bz2',
+     'gz', 'lz', and 'xz'. If this option is used, the files are passed to
+     the corresponding decompressor without verifying their format, and any
+     files in a format that the decompressor can't understand will fail.
+     For example, '--force-format=gz' can test gzipped (.gz) and compress'd
+     (.Z) files if the compressor used is GNU gzip.
 
 '-q'
 '--quiet'
@@ -669,8 +664,8 @@ environmental problems (file not found, invalid flags, I/O errors, etc),
 '-r'
 '--recursive'
      For each directory operand, read and process all files in that
-     directory, recursively. Follow symbolic links in the command line,
-     but skip symlinks that are encountered recursively.
+     directory, recursively. Follow symbolic links given in the command
+     line, but skip symbolic links that are encountered recursively.
 
 '-R'
 '--dereference-recursive'
@@ -689,68 +684,69 @@ File: zutils.info,  Node: Zupdate,  Next: Problems,  Prev: Ztest,  Up: Top
 9 Zupdate
 *********
 
-zupdate recompresses files from bzip2, gzip, and xz formats to lzip
-format. Each original is compared with the new file and then deleted.
-Only regular files with standard file name extensions are recompressed,
-other files are ignored. Compressed files are decompressed and then
-recompressed on the fly; no temporary files are created. If an error
-happens while recompressing a file, zupdate exits immediately without
-recompressing the rest of the files. The lzip format is chosen as
-destination because it is the most appropriate for long-term data
-archiving.
+zupdate recompresses files from bzip2, gzip, and xz formats to lzip format.
+Each original is compared with the new file and then deleted. Only regular
+files with standard file name extensions are recompressed, other files are
+ignored. Compressed files are decompressed and then recompressed on the fly;
+no temporary files are created. If an error happens while recompressing a
+file, zupdate exits immediately without recompressing the rest of the files.
+The lzip format is chosen as destination because it is the most appropriate
+for long-term data archiving.
 
-   If no files are specified, recursive searches examine the current
-working directory, and nonrecursive searches do nothing.
+   If no files are specified, recursive searches examine the current working
+directory, and nonrecursive searches do nothing.
 
    If the lzip compressed version of a file already exists, the file is
-skipped unless the '--force' option is given. In this case, if the
-comparison with the existing lzip version fails, an error is returned
-and the original file is not deleted. The operation of zupdate is meant
-to be safe and not produce any data loss. Therefore, existing lzip
-compressed files are never overwritten nor deleted.
+skipped unless the option '--force' is given. In this case, if the
+comparison with the existing lzip version fails, an error is returned and
+the original file is not deleted. The operation of zupdate is meant to be
+safe and not cause any data loss. Therefore, existing lzip compressed files
+are never overwritten nor deleted.
 
-   Combining the '--force' and '--keep' options, as in
-'zupdate -f -k *.gz', verifies that there are no differences between
-each pair of files in a multiformat set of files.
+   Combining the options '--force' and '--keep', as in
+'zupdate -f -k *.gz', verifies that there are no differences between each
+pair of files in a multiformat set of files.
 
    The names of the original files must have one of the following
-extensions: '.bz2', '.tbz', '.tbz2', '.gz', '.tgz', '.xz', '.txz'. The
-files produced have the extensions '.lz' or '.tar.lz'.
-
-   Recompressing a file is much like copying or moving it; therefore
-zupdate preserves the access and modification dates, permissions, and,
-when possible, ownership of the file just as 'cp -p' does. (If the user
-ID or the group ID can't be duplicated, the file permission bits S_ISUID
-and S_ISGID are cleared).
+extensions:
+'.bz2', '.gz', and '.xz' are recompressed to '.lz'.
+'.tbz', '.tbz2', '.tgz', and '.txz' are recompressed to '.tlz'.
+Keeping the combined extensions ('.tgz' -> '.tlz') may be useful when
+recompressing Slackware packages, for example.
+
+   Recompressing a file is much like copying or moving it; therefore zupdate
+preserves the access and modification dates, permissions, and, when
+possible, ownership of the file just as 'cp -p' does. (If the user ID or
+the group ID can't be duplicated, the file permission bits S_ISUID and
+S_ISGID are cleared).
 
    The format for running zupdate is:
 
      zupdate [OPTIONS] [FILES]
 
-Exit status is 0 if all the compressed files were successfully
-recompressed (if needed), compared and deleted (if requested). Non-zero
-otherwise.
+Exit status is 0 if all the compressed files were successfully recompressed
+(if needed), compared, and deleted (if requested). Non-zero otherwise.
 
    zupdate supports the following options:
 
 '-f'
 '--force'
-     Don't skip a file for which a lzip compressed version already
-     exists.  '--force' compares the content of the input file with the
-     content of the existing lzip file and deletes the input file if
-     both contents are identical.
+     Don't skip a file for which a lzip compressed version already exists.
+     '--force' compares the content of the input file with the content of
+     the existing lzip file and deletes the input file if both contents are
+     identical.
 
 '-k'
 '--keep'
-     Keep (don't delete) the input file after comparing it with the
-     lzip file.
+     Keep (don't delete) the input file after comparing it with the lzip
+     file.
 
 '-l'
 '--lzip-verbose'
-     Pass a '-v' option to the lzip compressor so that it shows the
-     compression ratio for each file processed. Using lzip 1.15 and
-     newer, a second '-l' shows the progress of compression. Use it
-     together with '-v' to see the name of the file.
+     Pass one option '-v' to the lzip compressor so that it shows the
+     compression ratio for each file processed. Using lzip 1.15 or newer, a
+     second '-l' shows the progress of compression. Use it together with
+     '-v' to see the name of the file.
 
 '-q'
 '--quiet'
@@ -759,8 +755,8 @@ otherwise.
 '-r'
 '--recursive'
      For each directory operand, read and process all files in that
-     directory, recursively. Follow symbolic links in the command line,
-     but skip symlinks that are encountered recursively.
+     directory, recursively. Follow symbolic links given in the command
+     line, but skip symbolic links that are encountered recursively.
 
 '-R'
 '--dereference-recursive'
@@ -769,12 +765,13 @@ otherwise.
 
 '-v'
 '--verbose'
-     Verbose mode. Show the files being processed. A second '-v' also
-     shows the files being ignored.
+     Verbose mode. Show the files being processed. A second '-v' also shows
+     the files being ignored.
 
 '-0 .. -9'
-     Set the compression level of lzip. By default zupdate passes '-9'
-     to lzip.
+     Set the compression level of lzip. By default zupdate passes '-9' to
+     lzip. Custom compression options can be passed to lzip with the option
+     '--lz'. For example '--lz='lzip -9 -s64MiB''.
 
 
 
@@ -783,14 +780,14 @@ File: zutils.info,  Node: Problems,  Next: Concept index,  Prev: Zupdate,  Up: T
 10 Reporting bugs
 *****************
 
-There are probably bugs in zutils. There are certainly errors and
-omissions in this manual. If you report them, they will get fixed. If
-you don't, no one will ever know about them and they will remain unfixed
-for all eternity, if not longer.
+There are probably bugs in zutils. There are certainly errors and omissions
+in this manual. If you report them, they will get fixed. If you don't, no
+one will ever know about them and they will remain unfixed for all
+eternity, if not longer.
 
    If you find a bug in zutils, please send electronic mail to
-<zutils-bug@nongnu.org>. Include the version number, which you can find
-by running 'zupdate --version'.
+<zutils-bug@nongnu.org>. Include the version number, which you can find by
+running 'zupdate --version'.
 
 
 File: zutils.info,  Node: Concept index,  Prev: Problems,  Up: Top
@@ -801,34 +798,34 @@ Concept index
 
 * Menu:
 
-* bugs:                                  Problems.              (line 6)
-* common options:                        Common options.        (line 6)
-* getting help:                          Problems.              (line 6)
-* introduction:                          Introduction.          (line 6)
-* the zutilsrc file:                     The zutilsrc file.     (line 6)
-* zcat:                                  Zcat.                  (line 6)
-* zcmp:                                  Zcmp.                  (line 6)
-* zdiff:                                 Zdiff.                 (line 6)
-* zgrep:                                 Zgrep.                 (line 6)
-* ztest:                                 Ztest.                 (line 6)
-* zupdate:                               Zupdate.               (line 6)
+* bugs:                                  Problems.                  (line 6)
+* common options:                        Common options.            (line 6)
+* getting help:                          Problems.                  (line 6)
+* introduction:                          Introduction.              (line 6)
+* the zutilsrc file:                     The zutilsrc file.         (line 6)
+* zcat:                                  Zcat.                      (line 6)
+* zcmp:                                  Zcmp.                      (line 6)
+* zdiff:                                 Zdiff.                     (line 6)
+* zgrep:                                 Zgrep.                     (line 6)
+* ztest:                                 Ztest.                     (line 6)
+* zupdate:                               Zupdate.                   (line 6)
 
 
 
 Tag Table:
 Node: Top222
-Node: Introduction1149
+Node: Introduction1148
 Node: Common options3773
-Ref: compressor-requirements5596
-Node: The zutilsrc file5968
-Node: Zcat6893
-Node: Zcmp9445
-Node: Zdiff11904
-Node: Zgrep14608
-Node: Ztest18603
-Node: Zupdate20938
-Node: Problems24364
-Node: Concept index24898
+Ref: compressor-requirements5844
+Node: The zutilsrc file6216
+Node: Zcat7149
+Node: Zcmp9712
+Node: Zdiff12202
+Node: Zgrep14942
+Node: Ztest18944
+Node: Zupdate21451
+Node: Problems25123
+Node: Concept index25657
 
 End Tag Table
 
diff --git a/doc/zutils.texi b/doc/zutils.texi
index 789643a..bb1c3b1 100644
--- a/doc/zutils.texi
+++ b/doc/zutils.texi
@@ -6,8 +6,8 @@
 @finalout
 @c %**end of header
 
-@set UPDATED 1 January 2019
-@set VERSION 1.8
+@set UPDATED 27 June 2020
+@set VERSION 1.9
 
 @dircategory Data Compression
 @direntry
@@ -49,53 +49,54 @@ This manual is for Zutils (version @value{VERSION}, @value{UPDATED}).
 @end menu
 
 @sp 1
-Copyright @copyright{} 2009-2019 Antonio Diaz Diaz.
+Copyright @copyright{} 2009-2020 Antonio Diaz Diaz.
 
-This manual is free documentation: you have unlimited permission
-to copy, distribute and modify it.
+This manual is free documentation: you have unlimited permission to copy,
+distribute, and modify it.
 
 
 @node Introduction
 @chapter Introduction
 @cindex introduction
 
-Zutils is a collection of utilities able to process any combination of
-compressed and uncompressed files transparently. If any given file,
-including standard input, is compressed, its decompressed content is
-used. Compressed files are decompressed on the fly; no temporary files
-are created.
+@uref{http://www.nongnu.org/zutils/zutils.html,,Zutils}
+is a collection of utilities able to process any combination of
+compressed and uncompressed files transparently. If any file given,
+including standard input, is compressed, its decompressed content is used.
+Compressed files are decompressed on the fly; no temporary files are
+created.
 
 These utilities are not wrapper scripts but safer and more efficient C++
-programs. In particular the @samp{--recursive} option is very efficient
-in those utilities supporting it.
+programs. In particular the option @samp{--recursive} is very efficient in
+those utilities supporting it.
 
 @noindent
-The utilities provided are zcat, zcmp, zdiff, zgrep, ztest and zupdate.@*
-The formats supported are bzip2, gzip, lzip and xz.@*
-Zutils uses external compressors. The compressor to be used for each
-format is configurable at runtime.
-
-zcat, zcmp, zdiff, and zgrep are improved replacements for the shell
-scripts provided by GNU gzip. ztest is unique to zutils. zupdate is
-similar to gzip's znew.
-
-NOTE: Bzip2 and lzip provide well-defined values of exit status, which
-makes them safe to use with zutils. Gzip and xz may return ambiguous
-warning values, making them less reliable back ends for zutils.
+The utilities provided are zcat, zcmp, zdiff, zgrep, ztest, and zupdate.@*
+The formats supported are bzip2, gzip, lzip, and xz.@*
+Zutils uses external compressors. The compressor to be used for each format
+is configurable at runtime.
+
+zcat, zcmp, zdiff, and zgrep are improved replacements for the shell scripts
+provided by GNU gzip. ztest is unique to zutils. zupdate is similar to
+gzip's znew.
+
+NOTE: Bzip2 and lzip provide well-defined values of exit status, which makes
+them safe to use with zutils. Gzip and xz may return ambiguous warning
+values, making them less reliable back ends for zutils.
 @xref{compressor-requirements}.
 
-FORMAT NOTE 1: The @samp{--format} option allows the processing of a
-subset of formats in recursive mode and when trying compressed file
-names: @w{@samp{zgrep foo -r --format=bz2,lz somedir somefile.tar}}.
+FORMAT NOTE 1: The option @samp{--format} allows the processing of a subset
+of formats in recursive mode and when trying compressed file names:
+@w{@samp{zgrep foo -r --format=bz2,lz somedir somefile.tar}}.
 
-FORMAT NOTE 2: If the @samp{--force-format} option is given, the files
-are passed to the corresponding decompressor without verifying their
-format, allowing for example the processing of compress'd (.Z) files
-with gzip: @w{@samp{zcmp --force-format=gz file.Z file.lz}}.
+FORMAT NOTE 2: If the option @samp{--force-format} is given, the files are
+passed to the corresponding decompressor without verifying their format,
+allowing for example the processing of compress'd (.Z) files with gzip:
+@w{@samp{zcmp --force-format=gz file.Z file.lz}}.
 
-LANGUAGE NOTE: Uncompressed = not compressed = plain data; it may never
-have been compressed. Decompressed is used to refer to data which have
-undergone the process of decompression.
+LANGUAGE NOTE: Uncompressed = not compressed = plain data; it may never have
+been compressed. Decompressed is used to refer to data which have undergone
+the process of decompression.
 
 @sp 1
 Numbers given as arguments to options (positions, sizes) may be followed
@@ -120,9 +121,13 @@ Table of SI and binary prefixes (unit multipliers):
 @chapter Common options
 @cindex common options
 
-The following options are available in all the utilities. Rather than
-writing identical descriptions for each of the programs, they are
-described here.
+The following
+@uref{http://www.nongnu.org/arg-parser/manual/arg_parser_manual.html#Argument-syntax,,options}:
+are available in all the utilities. Rather than writing identical
+descriptions for each of the programs, they are described here.
+@ifnothtml
+@xref{Argument syntax,,,arg_parser}.
+@end ifnothtml
 
 @table @code
 @item -h
@@ -139,7 +144,7 @@ This version number should be included in all bug reports.
 @itemx --format=@var{format_list}
 Process only the formats listed in the comma-separated
 @var{format_list}. Valid formats are @samp{bz2}, @samp{gz}, @samp{lz},
-@samp{xz} and @samp{un} for @samp{uncompressed}, meaning "any file name
+@samp{xz}, and @samp{un} for @samp{uncompressed}, meaning "any file name
 without a known extension". This option excludes files based on
 extension, instead of format, because it is more efficient. The
 exclusion only applies to names generated automatically (for example
@@ -165,19 +170,22 @@ Don't read the runtime configuration file @samp{zutilsrc}.
 @itemx --gz=@var{command}
 @itemx --lz=@var{command}
 @itemx --xz=@var{command}
-Set program (may include arguments) to be used as (de)compressor for the
-given format. The name of the program can't begin with @samp{-}. These
-options override the values set in @file{zutilsrc}. The compression
-program used must meet three requirements:
+Set program to be used as (de)compressor for the corresponding format.
+@var{command} may include arguments. For example
+@w{@samp{--lz='plzip --threads=2'}}. The program set with @samp{--lz} is
+used for both compression and decompression. The other three are used only
+for decompression. The name of the program can't begin with @samp{-}. These
+options override the values set in @file{zutilsrc}. The compression program
+used must meet three requirements:
 
 @anchor{compressor-requirements}
 @enumerate
 @item
-When called with the @samp{-d} option, it must read compressed data from
+When called with the option @samp{-d}, it must read compressed data from
 the standard input and produce decompressed data on the standard output.
 @item
-If the @samp{-q} option is passed to zutils, the compression program
-must also accept it.
+If the option @samp{-q} is passed to zutils, the compression program must
+also accept it.
 @item
 It must return 0 if no errors occurred, and a non-zero value otherwise.
 @end enumerate
@@ -206,12 +214,12 @@ are further instructions in it):
 @item
 Any line beginning with @samp{#} is a comment line.
 @item
-Each non-comment line defines the command to be used for the given
+Each non-comment line defines the command to be used for the corresponding
 format, with the syntax:
 @example
 <format> = <compressor> [options]
 @end example
-where <format> is one of @samp{bz2}, @samp{gz}, @samp{lz} or @samp{xz}.
+where <format> is one of @samp{bz2}, @samp{gz}, @samp{lz}, or @samp{xz}.
 @end enumerate
 
 
@@ -219,20 +227,20 @@ where <format> is one of @samp{bz2}, @samp{gz}, @samp{lz} or @samp{xz}.
 @chapter Zcat
 @cindex zcat
 
-zcat copies each given file to standard output. If any given file is
-compressed, its decompressed content is used. If a given file does not
-exist, and its name does not end with one of the known extensions, zcat
-tries the compressed file names corresponding to the formats supported.
-If a file fails to decompress, zcat continues copying the rest of the
-files.
+zcat copies each @var{file} argument to standard output in sequence. If any
+file given is compressed, its decompressed content is copied. If a file
+given does not exist, and its name does not end with one of the known
+extensions, zcat tries the compressed file names corresponding to the
+formats supported. If a file fails to decompress, zcat continues copying the
+rest of the files.
 
 If a file is specified as @samp{-}, data are read from standard input,
 decompressed if needed, and sent to standard output. Data read from
 standard input must be of the same type; all uncompressed or all in the
-same compression format.
+same compressed format.
 
-If no files are specified, recursive searches examine the current
-working directory, and nonrecursive searches read standard input.
+If no files are specified, recursive searches examine the current working
+directory, and nonrecursive searches read standard input.
 
 The format for running zcat is:
 
@@ -241,7 +249,7 @@ zcat [@var{options}] [@var{files}]
 @end example
 
 @noindent
-Exit status is 0 if no errors occurred, non-zero otherwise.
+Exit status is 0 if no errors occurred, 1 otherwise.
 
 zcat supports the following options:
 
@@ -268,8 +276,8 @@ Number all output lines, starting with 1. The line count is unlimited.
 
 @item -O @var{format}
 @itemx --force-format=@var{format}
-Force the given compression format. Valid values for @var{format} are
-@samp{bz2}, @samp{gz}, @samp{lz} and @samp{xz}. If this option is used,
+Force the compressed format given. Valid values for @var{format} are
+@samp{bz2}, @samp{gz}, @samp{lz}, and @samp{xz}. If this option is used,
 the files are passed to the corresponding decompressor without verifying
 their format, and the exact file name must be given. Other names won't
 be tried.
@@ -280,14 +288,14 @@ Quiet operation. Suppress all messages.
 
 @item -r
 @itemx --recursive
-For each directory operand, read and process all files in that
-directory, recursively. Follow symbolic links in the command line, but
-skip symlinks that are encountered recursively.
+For each directory operand, read and process all files in that directory,
+recursively. Follow symbolic links given in the command line, but skip
+symbolic links that are encountered recursively.
 
 @item -R
 @itemx --dereference-recursive
-For each directory operand, read and process all files in that
-directory, recursively, following all symbolic links.
+For each directory operand, read and process all files in that directory,
+recursively, following all symbolic links.
 
 @item -s
 @itemx --squeeze-blank
@@ -316,11 +324,12 @@ Verbose mode. Show error messages.
 @chapter Zcmp
 @cindex zcmp
 
-zcmp compares two files (@samp{-} means standard input), and if they
-differ, tells the first byte and line number where they differ. Bytes
-and lines are numbered starting with 1. If any given file is compressed,
-its decompressed content is used. Compressed files are decompressed on
-the fly; no temporary files are created.
+zcmp compares two files and, if they differ, writes to standard output the
+first byte and line number where they differ. Bytes and lines are numbered
+starting with 1. A hyphen @samp{-} used as a @var{file} argument means
+standard input. If any file given is compressed, its decompressed content is
+used. Compressed files are decompressed on the fly; no temporary files are
+created.
 
 The format for running zcmp is:
 
@@ -329,10 +338,11 @@ zcmp [@var{options}] @var{file1} [@var{file2}]
 @end example
 
 @noindent
-This compares @var{file1} to @var{file2}. If @var{file2} is omitted zcmp
-tries the following:
+This compares @var{file1} to @var{file2}. The standard input is used only if
+@var{file1} or @var{file2} refers to standard input. If @var{file2} is
+omitted zcmp tries the following:
 
-@enumerate
+@itemize -
 @item
 If @var{file1} is compressed, compares its decompressed contents with
 the corresponding uncompressed file (the name of @var{file1} with the
@@ -340,10 +350,7 @@ extension removed).
 @item
 If @var{file1} is uncompressed, compares it with the decompressed
 contents of @var{file1}.[lz|bz2|gz|xz] (the first one that is found).
-@item
-If no suitable file is found, compares @var{file1} with data read from
-standard input.
-@end enumerate
+@end itemize
 
 @noindent
 An exit status of 0 means no differences were found, 1 means some
@@ -379,10 +386,10 @@ Compare at most @var{count} input bytes.
 
 @item -O [@var{format1}][,@var{format2}]
 @itemx --force-format=[@var{format1}][,@var{format2}]
-Force the given compression formats. Any of @var{format1} or
+Force the compressed formats given. Any of @var{format1} or
 @var{format2} may be omitted and the corresponding format will be
 automatically detected. Valid values for @var{format} are @samp{bz2},
-@samp{gz}, @samp{lz} and @samp{xz}. If at least one format is specified
+@samp{gz}, @samp{lz}, and @samp{xz}. If at least one format is specified
 with this option, the file is passed to the corresponding decompressor
 without verifying its format, and the exact file names of both
 @var{file1} and @var{file2} must be given. Other names won't be tried.
@@ -401,11 +408,12 @@ files differ.
 @chapter Zdiff
 @cindex zdiff
 
-zdiff compares two files (@samp{-} means standard input), and if they
-differ, shows the differences line by line. If any given file is
-compressed, its decompressed content is used. zdiff is a front end to
-the diff program and has the limitation that messages from diff refer to
-temporary file names instead of those specified.
+zdiff compares two files and, if they differ, writes to standard output the
+differences line by line. A hyphen @samp{-} used as a @var{file} argument
+means standard input. If any file given is compressed, its decompressed
+content is used. zdiff is a front end to the program diff and has the
+limitation that messages from diff refer to temporary file names instead of
+those specified.
 
 The format for running zdiff is:
 
@@ -414,10 +422,11 @@ zdiff [@var{options}] @var{file1} [@var{file2}]
 @end example
 
 @noindent
-This compares @var{file1} to @var{file2}. If @var{file2} is omitted
-zdiff tries the following:
+This compares @var{file1} to @var{file2}. The standard input is used only if
+@var{file1} or @var{file2} refers to standard input. If @var{file2} is
+omitted zdiff tries the following:
 
-@enumerate
+@itemize -
 @item
 If @var{file1} is compressed, compares its decompressed contents with
 the corresponding uncompressed file (the name of @var{file1} with the
@@ -425,10 +434,7 @@ extension removed).
 @item
 If @var{file1} is uncompressed, compares it with the decompressed
 contents of @var{file1}.[lz|bz2|gz|xz] (the first one that is found).
-@item
-If no suitable file is found, compares @var{file1} with data read from
-standard input.
-@end enumerate
+@end itemize
 
 @noindent
 An exit status of 0 means no differences were found, 1 means some
@@ -471,10 +477,10 @@ Ignore case differences in file contents.
 
 @item -O [@var{format1}][,@var{format2}]
 @itemx --force-format=[@var{format1}][,@var{format2}]
-Force the given compression formats. Any of @var{format1} or
+Force the compressed formats given. Any of @var{format1} or
 @var{format2} may be omitted and the corresponding format will be
 automatically detected. Valid values for @var{format} are @samp{bz2},
-@samp{gz}, @samp{lz} and @samp{xz}. If at least one format is specified
+@samp{gz}, @samp{lz}, and @samp{xz}. If at least one format is specified
 with this option, the file is passed to the corresponding decompressor
 without verifying its format, and the exact file names of both
 @var{file1} and @var{file2} must be given. Other names won't be tried.
@@ -517,9 +523,9 @@ Ignore all white space.
 @chapter Zgrep
 @cindex zgrep
 
-zgrep is a front end to the grep program that allows transparent search
-on any combination of compressed and uncompressed files. If any given
-file is compressed, its decompressed content is used. If a given file
+zgrep is a front end to the program grep that allows transparent search
+on any combination of compressed and uncompressed files. If any file
+given is compressed, its decompressed content is used. If a file given
 does not exist, and its name does not end with one of the known
 extensions, zgrep tries the compressed file names corresponding to the
 formats supported. If a file fails to decompress, zgrep continues
@@ -528,10 +534,10 @@ searching the rest of the files.
 If a file is specified as @samp{-}, data are read from standard input,
 decompressed if needed, and fed to grep. Data read from standard input
 must be of the same type; all uncompressed or all in the same
-compression format.
+compressed format.
 
-If no files are specified, recursive searches examine the current
-working directory, and nonrecursive searches read standard input.
+If no files are specified, recursive searches examine the current working
+directory, and nonrecursive searches read standard input.
 
 The format for running zgrep is:
 
@@ -572,7 +578,7 @@ Only print a count of matching lines per file.
 Print @var{n} lines of output context.
 
 @item --color[=@var{when}]
-Show matched strings in color. @var{when} is @samp{never}, @samp{always}
+Show matched strings in color. @var{when} is @samp{never}, @samp{always},
 or @samp{auto}.
 
 @item -e @var{pattern}
@@ -587,9 +593,9 @@ Treat @var{pattern} as an extended regular expression.
 @itemx --file=@var{file}
 Obtain patterns from @var{file}, one per line.@*
 When searching in several files at once, command substitution can be
-used with @code{-e} to read @var{file} only once, for example if
+used with @samp{-e} to read @var{file} only once, for example if
 @var{file} is not a regular file:
-@w{@code{zgrep -e "$(cat @var{file})" file1.lz file2.gz}}
+@w{@samp{zgrep -e "$(cat @var{file})" file1.lz file2.gz}}
 
 @item -F
 @itemx --fixed-strings
@@ -633,8 +639,8 @@ Show only the part of matching lines that actually matches @var{pattern}.
 
 @item -O @var{format}
 @itemx --force-format=@var{format}
-Force the given compression format. Valid values for @var{format} are
-@samp{bz2}, @samp{gz}, @samp{lz} and @samp{xz}. If this option is used,
+Force the compressed format given. Valid values for @var{format} are
+@samp{bz2}, @samp{gz}, @samp{lz}, and @samp{xz}. If this option is used,
 the files are passed to the corresponding decompressor without verifying
 their format, and the exact file name must be given. Other names won't
 be tried.
@@ -646,14 +652,14 @@ found, even if an error was detected.
 
 @item -r
 @itemx --recursive
-For each directory operand, read and process all files in that
-directory, recursively. Follow symbolic links in the command line, but
-skip symlinks that are encountered recursively.
+For each directory operand, read and process all files in that directory,
+recursively. Follow symbolic links given in the command line, but skip
+symbolic links that are encountered recursively.
 
 @item -R
 @itemx --dereference-recursive
-For each directory operand, read and process all files in that
-directory, recursively, following all symbolic links.
+For each directory operand, read and process all files in that directory,
+recursively, following all symbolic links.
 
 @item -s
 @itemx --no-messages
@@ -681,15 +687,17 @@ Match only whole lines.
 @chapter Ztest
 @cindex ztest
 
-ztest verifies the integrity of the specified compressed files.
+ztest verifies the integrity of the compressed files specified.
 Uncompressed files are ignored. If a file is specified as @samp{-}, the
 integrity of compressed data read from standard input is verified. Data
-read from standard input must be all in the same compression format. If
-a file fails to decompress, ztest continues verifying the rest of the
-files.
+read from standard input must be all in the same compressed format. If
+a file fails to decompress, does not exist, can't be opened, or is a
+terminal, ztest continues verifying the rest of the files. A final
+diagnostic is shown at verbosity level 1 or higher if any file fails the
+test when testing multiple files.
 
-If no files are specified, recursive searches examine the current
-working directory, and nonrecursive searches read standard input.
+If no files are specified, recursive searches examine the current working
+directory, and nonrecursive searches read standard input.
 
 Note that error detection in the xz format is broken. First, some xz
 files lack integrity information. Second, not all xz decompressors can
@@ -717,13 +725,12 @@ ztest supports the following options:
 @table @code
 @item -O @var{format}
 @itemx --force-format=@var{format}
-Force the given compression format. Valid values for @var{format} are
-@samp{bz2}, @samp{gz}, @samp{lz} and @samp{xz}. If this option is used,
-the files are passed to the corresponding decompressor without verifying
-their format, and any files in a format that the decompressor can't
-understand will fail. For example, @samp{--force-format=gz} can test
-gzipped (.gz) and compress'd (.Z) files if the compressor used is GNU
-gzip.
+Force the compressed format given. Valid values for @var{format} are
+@samp{bz2}, @samp{gz}, @samp{lz}, and @samp{xz}. If this option is used, the
+files are passed to the corresponding decompressor without verifying their
+format, and any files in a format that the decompressor can't understand
+will fail. For example, @samp{--force-format=gz} can test gzipped (.gz) and
+compress'd (.Z) files if the compressor used is GNU gzip.
 
 @item -q
 @itemx --quiet
@@ -731,14 +738,14 @@ Quiet operation. Suppress all messages.
 
 @item -r
 @itemx --recursive
-For each directory operand, read and process all files in that
-directory, recursively. Follow symbolic links in the command line, but
-skip symlinks that are encountered recursively.
+For each directory operand, read and process all files in that directory,
+recursively. Follow symbolic links given in the command line, but skip
+symbolic links that are encountered recursively.
 
 @item -R
 @itemx --dereference-recursive
-For each directory operand, read and process all files in that
-directory, recursively, following all symbolic links.
+For each directory operand, read and process all files in that directory,
+recursively, following all symbolic links.
 
 @item -v
 @itemx --verbose
@@ -752,40 +759,41 @@ Further -v's increase the verbosity level.
 @chapter Zupdate
 @cindex zupdate
 
-zupdate recompresses files from bzip2, gzip, and xz formats to lzip
-format. Each original is compared with the new file and then deleted.
-Only regular files with standard file name extensions are recompressed,
-other files are ignored. Compressed files are decompressed and then
-recompressed on the fly; no temporary files are created. If an error
-happens while recompressing a file, zupdate exits immediately without
-recompressing the rest of the files. The lzip format is chosen as
-destination because it is the most appropriate for long-term data
-archiving.
+zupdate recompresses files from bzip2, gzip, and xz formats to lzip format.
+Each original is compared with the new file and then deleted. Only regular
+files with standard file name extensions are recompressed, other files are
+ignored. Compressed files are decompressed and then recompressed on the fly;
+no temporary files are created. If an error happens while recompressing a
+file, zupdate exits immediately without recompressing the rest of the files.
+The lzip format is chosen as destination because it is the most appropriate
+for long-term data archiving.
 
-If no files are specified, recursive searches examine the current
-working directory, and nonrecursive searches do nothing.
+If no files are specified, recursive searches examine the current working
+directory, and nonrecursive searches do nothing.
 
 If the lzip compressed version of a file already exists, the file is
-skipped unless the @samp{--force} option is given. In this case, if the
+skipped unless the option @samp{--force} is given. In this case, if the
 comparison with the existing lzip version fails, an error is returned
 and the original file is not deleted. The operation of zupdate is meant
-to be safe and not produce any data loss. Therefore, existing lzip
+to be safe and not cause any data loss. Therefore, existing lzip
 compressed files are never overwritten nor deleted.
 
-Combining the @samp{--force} and @samp{--keep} options, as in
-@w{@code{zupdate -f -k *.gz}}, verifies that there are no differences
+Combining the options @samp{--force} and @samp{--keep}, as in
+@w{@samp{zupdate -f -k *.gz}}, verifies that there are no differences
 between each pair of files in a multiformat set of files.
 
-The names of the original files must have one of the following
-extensions: @samp{.bz2}, @samp{.tbz}, @samp{.tbz2}, @samp{.gz},
-@samp{.tgz}, @samp{.xz}, @samp{.txz}. The files produced have the
-extensions @samp{.lz} or @samp{.tar.lz}.
+The names of the original files must have one of the following extensions:@*
+@samp{.bz2}, @samp{.gz}, and @samp{.xz} are recompressed to @samp{.lz}.@*
+@samp{.tbz}, @samp{.tbz2}, @samp{.tgz}, and @samp{.txz} are recompressed to
+@samp{.tlz}.@*
+Keeping the combined extensions (@samp{.tgz} --> @samp{.tlz}) may be useful
+when recompressing Slackware packages, for example.
 
-Recompressing a file is much like copying or moving it; therefore
-zupdate preserves the access and modification dates, permissions, and,
-when possible, ownership of the file just as @samp{cp -p} does. (If the user
-ID or the group ID can't be duplicated, the file permission bits S_ISUID
-and S_ISGID are cleared).
+Recompressing a file is much like copying or moving it; therefore zupdate
+preserves the access and modification dates, permissions, and, when
+possible, ownership of the file just as @samp{cp -p} does. (If the user ID or
+the group ID can't be duplicated, the file permission bits S_ISUID and
+S_ISGID are cleared).
 
 The format for running zupdate is:
 
@@ -794,9 +802,8 @@ zupdate [@var{options}] [@var{files}]
 @end example
 
 @noindent
-Exit status is 0 if all the compressed files were successfully
-recompressed (if needed), compared and deleted (if requested). Non-zero
-otherwise.
+Exit status is 0 if all the compressed files were successfully recompressed
+(if needed), compared, and deleted (if requested). Non-zero otherwise.
 
 zupdate supports the following options:
 
@@ -814,8 +821,8 @@ Keep (don't delete) the input file after comparing it with the lzip file.
 
 @item -l
 @itemx --lzip-verbose
-Pass a @samp{-v} option to the lzip compressor so that it shows the
-compression ratio for each file processed. Using lzip 1.15 and newer, a
+Pass one option @samp{-v} to the lzip compressor so that it shows the
+compression ratio for each file processed. Using lzip 1.15 or newer, a
 second @samp{-l} shows the progress of compression. Use it together with
 @samp{-v} to see the name of the file.
 
@@ -825,14 +832,14 @@ Quiet operation. Suppress all messages.
 
 @item -r
 @itemx --recursive
-For each directory operand, read and process all files in that
-directory, recursively. Follow symbolic links in the command line, but
-skip symlinks that are encountered recursively.
+For each directory operand, read and process all files in that directory,
+recursively. Follow symbolic links given in the command line, but skip
+symbolic links that are encountered recursively.
 
 @item -R
 @itemx --dereference-recursive
-For each directory operand, read and process all files in that
-directory, recursively, following all symbolic links.
+For each directory operand, read and process all files in that directory,
+recursively, following all symbolic links.
 
 @item -v
 @itemx --verbose
@@ -840,8 +847,9 @@ Verbose mode. Show the files being processed. A second @samp{-v} also
 shows the files being ignored.
 
 @item -0 .. -9
-Set the compression level of lzip. By default zupdate passes @samp{-9}
-to lzip.
+Set the compression level of lzip. By default zupdate passes @samp{-9} to
+lzip. Custom compression options can be passed to lzip with the option
+@samp{--lz}. For example @w{@samp{--lz='lzip -9 -s64MiB'}}.
 
 @end table
 
@@ -858,7 +866,7 @@ for all eternity, if not longer.
 
 If you find a bug in zutils, please send electronic mail to
 @email{zutils-bug@@nongnu.org}. Include the version number, which you can
-find by running @w{@code{zupdate --version}}.
+find by running @w{@samp{zupdate --version}}.
 
 
 @node Concept index