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diff --git a/gnu/usr.bin/grep/doc/grep.texi b/gnu/usr.bin/grep/doc/grep.texi index beb2410f956d..32b27c419926 100644 --- a/gnu/usr.bin/grep/doc/grep.texi +++ b/gnu/usr.bin/grep/doc/grep.texi @@ -35,7 +35,8 @@ Published by the Free Software Foundation, 59 Temple Place - Suite 330 Boston, MA 02111-1307, USA -Copyright 2000 Free Software Foundation, Inc. +@c man begin COPYRIGHT +Copyright @copyright{} 2000, 2001 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice @@ -43,20 +44,19 @@ are preserved on all copies. @ignore Permission is granted to process this file through TeX and print the -results, provided the printed document carries copying permission +results, provided the printed document carries a copying permission notice identical to this one except for the removal of this paragraph (this paragraph not being relevant to the printed manual). @end ignore -Permission is granted to copy and distribute modified versions of this -manual under the conditions for verbatim copying, provided that the entire -resulting derived work is distributed under the terms of a permission -notice identical to this one. - -Permission is granted to copy and distribute translations of this manual -into another language, under the above conditions for modified versions, -except that this permission notice may be stated in a translation approved -by the Foundation. +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.1 or +any later version published by the Free Software Foundation; with the +Invariant Sections being ``GNU General Public License'' and ``GNU Free +Documentation License'', with no Front-Cover Texts, and with no +Back-Cover Texts. A copy of the license is included in the section +entitled ``GNU Free Documentation License'' (@pxref{Copying}). +@c man end @end ifinfo @setchapternewpage off @@ -68,29 +68,21 @@ by the Foundation. @page @vskip 0pt plus 1filll -Copyright @copyright{} 2000 Free Software Foundation, Inc. +Copyright @copyright{} 2000, 2001 Free Software Foundation, Inc. @sp 2 Published by the Free Software Foundation, @* 59 Temple Place - Suite 330, @* Boston, MA 02111-1307, USA -Permission is granted to make and distribute verbatim copies of -this manual provided the copyright notice and this permission notice -are preserved on all copies. - -Permission is granted to copy and distribute modified versions of this -manual under the conditions for verbatim copying, provided that the entire -resulting derived work is distributed under the terms of a permission -notice identical to this one. - -Permission is granted to copy and distribute translations of this manual -into another language, under the above conditions for modified versions, -except that this permission notice may be stated in a translation approved -by the Foundation. - +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.1 or +any later version published by the Free Software Foundation; with the +Invariant Sections being ``GNU General Public License'' and ``GNU Free +Documentation License'', with no Front-Cover Texts, and with no +Back-Cover Texts. A copy of the license is included in the section +entitled ``GNU Free Documentation License''. @end titlepage -@page @ifnottex @@ -111,13 +103,14 @@ This document was produced for version @value{VERSION} of @sc{gnu} * Regular Expressions:: Regular Expressions. * Usage:: Examples. * Reporting Bugs:: Reporting Bugs. +* Copying:: License terms. * Concept Index:: A menu with all the topics in this manual. * Index:: A menu with all @command{grep} commands and command-line options. @end menu -@node Introduction +@node Introduction, Invoking, Top, Top @chapter Introduction @cindex Searching for a pattern. @@ -147,7 +140,7 @@ extensions. @item -c @itemx --count @opindex -c -@opindex -count +@opindex --count @cindex counting lines Suppress normal output; instead print a count of matching lines for each input file. With the @samp{-v}, @samp{--invert-match} option, @@ -192,6 +185,13 @@ The scanning of every file will stop on the first match. @cindex line numbering Prefix each line of output with the line number within its input file. +@item -o +@itemx --only-matching +@opindex -o +@opindex --only-matching +@cindex only matching +Print only the part of matching lines that actually matches @var{pattern}. + @item -q @itemx --quiet @itemx --silent @@ -199,8 +199,9 @@ Prefix each line of output with the line number within its input file. @opindex --quiet @opindex --silent @cindex quiet, silent -Quiet; suppress normal output. The scanning of every file will stop on -the first match. Also see the @samp{-s} or @samp{--no-messages} option. +Quiet; do not write anything to standard output. Exit immediately with +zero status if any match is found, even if an error was detected. Also +see the @samp{-s} or @samp{--no-messages} option. @item -s @itemx --no-messages @@ -254,12 +255,18 @@ Print @var{num} lines of trailing context after matching lines. Print @var{num} lines of leading context before matching lines. @item -C @var{num} -@itemx --context=[@var{num}] +@itemx --context=@var{num} @opindex -C @opindex --context @cindex context -Print @var{num} lines (default 2) of output context. +Print @var{num} lines of output context. +@item --colour[=@var{WHEN}] +@itemx --color[=@var{WHEN}] +@opindex --colour +@cindex highlight, color, colour +The matching string is surrounded by the marker specify in @var{GREP_COLOR}. +@var{WHEN} may be `never', `always', or `auto'. @item -@var{num} @opindex -NUM @@ -308,6 +315,17 @@ byte offsets depend on whether the @samp{-u} (@samp{--unix-byte-offsets}) option is used; see below. +@item -D @var{action} +@itemx --devices=@var{action} +@opindex -D +@opindex --devices +@cindex device search +If an input file is a device, FIFO or socket, use @var{action} to process it. +By default, @var{action} is @samp{read}, which means that devices are +read just as if they were ordinary files. +If @var{action} is @samp{skip}, devices, FIFOs and sockets are silently +skipped. + @item -d @var{action} @itemx --directories=@var{action} @opindex -d @@ -317,10 +335,10 @@ If an input file is a directory, use @var{action} to process it. By default, @var{action} is @samp{read}, which means that directories are read just as if they were ordinary files (some operating systems and filesystems disallow this, and will cause @command{grep} to print error -messages for every directory). If @var{action} is @samp{skip}, -directories are silently skipped. If @var{action} is @samp{recurse}, -@command{grep} reads all files under each directory, recursively; this is -equivalent to the @samp{-r} option. +messages for every directory or silently skip them). If @var{action} is +@samp{skip}, directories are silently skipped. If @var{action} is +@samp{recurse}, @command{grep} reads all files under each directory, +recursively; this is equivalent to the @samp{-r} option. @item -H @itemx --with-filename @@ -336,6 +354,18 @@ Print the filename for each match. @cindex no filename prefix Suppress the prefixing of filenames on output when multiple files are searched. +@item --line-buffered +@opindex --line-buffered +@cindex line buffering +Set the line buffering policy, this can be a performance penality. + +@item --label=@var{LABEL} +@opindex --label +@cindex changing name of standard input +Displays input actually coming from standard input as input coming from file +@var{LABEL}. This is especially useful for tools like zgrep, e.g. +@command{gzip -cd foo.gz |grep --label=foo something} + @item -L @itemx --files-without-match @opindex -L @@ -372,14 +402,69 @@ a non-word constituent character. Word-constituent characters are letters, digits, and the underscore. @item -r +@itemx -R @itemx --recursive @opindex -r @opindex --recursive @cindex recursive search @cindex searching directory trees For each directory mentioned in the command line, read and process all -files in that directory, recursively. This is the same as the @samp{-d -recurse} option. +files in that directory, recursively. This is the same as the +@samp{--directories=recurse} option. + +@item --include=@var{file_pattern} +@opindex --include +@cindex include files +@cindex searching directory trees +When processing directories recursively, only files matching @var{file_pattern} +will be search. + +@item --exclude=@var{file_pattern} +@opindex --exclude +@cindex exclude files +@cindex searching directory trees +When processing directories recursively, skip files matching @var{file_pattern}. + +@item -m @var{num} +@itemx --max-count=@var{num} +@opindex -m +@opindex --max-count +@cindex max-count +Stop reading a file after @var{num} matching lines. If the input is +standard input from a regular file, and @var{num} matching lines are +output, @command{grep} ensures that the standard input is positioned to +just after the last matching line before exiting, regardless of the +presence of trailing context lines. This enables a calling process +to resume a search. For example, the following shell script makes use +of it: + +@example +while grep -m 1 PATTERN +do + echo xxxx +done < FILE +@end example + +But the following probably will not work because a pipe is not a regular +file: + +@example +# This probably will not work. +cat FILE | +while grep -m 1 PATTERN +do + echo xxxx +done +@end example + +When @command{grep} stops after NUM matching lines, it outputs +any trailing context lines. Since context does not include matching +lines, @command{grep} will stop when it encounters another matching line. +When the @samp{-c} or @samp{--count} option is also used, +@command{grep} does not output a count greater than @var{num}. +When the @samp{-v} or @samp{--invert-match} option is +also used, @command{grep} stops after outputting @var{num} +non-matching lines. @item -y @opindex -y @@ -460,9 +545,20 @@ matching engine is used. @xref{Grep Programs}. @section Environment Variables Grep's behavior is affected by the following environment variables. + +A locale @code{LC_@var{foo}} is specified by examining the three +environment variables @env{LC_ALL}, @env{LC_@var{foo}}, and @env{LANG}, +in that order. The first of these variables that is set specifies the +locale. For example, if @env{LC_ALL} is not set, but @env{LC_MESSAGES} +is set to @samp{pt_BR}, then Brazilian Portuguese is used for the +@code{LC_MESSAGES} locale. The C locale is used if none of these +environment variables are set, or if the locale catalog is not +installed, or if @command{grep} was not compiled with national language +support (@sc{nls}). + @cindex environment variables -@table @code +@table @env @item GREP_OPTIONS @vindex GREP_OPTIONS @@ -476,23 +572,24 @@ any explicit options. Option specifications are separated by whitespace. A backslash escapes the next character, so it can be used to specify an option containing whitespace or a backslash. +@item GREP_COLOR +@vindex GREP_COLOR +@cindex highlight markers +This variable specifies the surrounding markers use to highlight the matching +text. The default is control ascii red. + @item LC_ALL -@itemx LC_MESSAGES +@itemx LC_COLLATE @itemx LANG @vindex LC_ALL -@vindex LC_MESSAGES +@vindex LC_COLLATE @vindex LANG -@cindex language of messages -@cindex message language +@cindex character type @cindex national language support @cindex NLS -@cindex translation of message language -These variables specify the @code{LC_MESSAGES} locale, which determines -the language that @command{grep} uses for messages. The locale is determined -by the first of these variables that is set. American English is used -if none of these environment variables are set, or if the message -catalog is not installed, or if @command{grep} was not compiled with national -language support (@sc{nls}). +These variables specify the @code{LC_COLLATE} locale, which determines +the collating sequence used to interpret range expressions like +@samp{[a-z]}. @item LC_ALL @itemx LC_CTYPE @@ -504,11 +601,22 @@ language support (@sc{nls}). @cindex national language support @cindex NLS These variables specify the @code{LC_CTYPE} locale, which determines the -type of characters, e.g., which characters are whitespace. The locale is -determined by the first of these variables that is set. The @sc{posix} -locale is used if none of these environment variables are set, or if the -locale catalog is not installed, or if @command{grep} was not compiled with -national language support (@sc{nls}). +type of characters, e.g., which characters are whitespace. + +@item LC_ALL +@itemx LC_MESSAGES +@itemx LANG +@vindex LC_ALL +@vindex LC_MESSAGES +@vindex LANG +@cindex language of messages +@cindex message language +@cindex national language support +@cindex NLS +@cindex translation of message language +These variables specify the @code{LC_MESSAGES} locale, which determines +the language that @command{grep} uses for messages. The default C +locale uses American English messages. @item POSIXLY_CORRECT @vindex POSIXLY_CORRECT @@ -539,10 +647,10 @@ only when @code{POSIXLY_CORRECT} is not set. @node Diagnostics @chapter Diagnostics -Normally, exit status is 0 if matches were found, and 1 if no matches -were found (the @samp{-v} option inverts the sense of the exit status). -Exit status is 2 if there were syntax errors in the pattern, -inaccessible input files, or other system errors. +Normally, exit status is 0 if selected lines are found and 1 otherwise. +But the exit status is 2 if an error occurred, unless the @option{-q} or +@option{--quiet} or @option{--silent} option is used and a selected line +is found. @node Grep Programs @chapter @command{grep} programs @@ -550,7 +658,7 @@ inaccessible input files, or other system errors. @command{grep} searches the named input files (or standard input if no files are named, or the file name @file{-} is given) for lines containing a match to the given pattern. By default, @command{grep} prints the -matching lines. There are three major variants of @command{grep}, +matching lines. There are four major variants of @command{grep}, controlled by the following options. @table @samp @@ -560,24 +668,30 @@ controlled by the following options. @opindex -G @opindex --basic-regexp @cindex matching basic regular expressions -Interpret pattern as a basic regular expression. This is the default. +Interpret the pattern as a basic regular expression. This is the default. @item -E @itemx --extended-regexp @opindex -E @opindex --extended-regexp @cindex matching extended regular expressions -Interpret pattern as an extended regular expression. - +Interpret the pattern as an extended regular expression. @item -F @itemx --fixed-strings @opindex -F @opindex --fixed-strings @cindex matching fixed strings -Interpret pattern as a list of fixed strings, separated +Interpret the pattern as a list of fixed strings, separated by newlines, any of which is to be matched. +@item -P +@itemx --perl-regexp +@opindex -P +@opindex --perl-regexp +@cindex matching Perl regular expressions +Interpret the pattern as a Perl regular expression. + @end table In addition, two variant programs @sc{egrep} and @sc{fgrep} are available. @@ -592,8 +706,8 @@ A @dfn{regular expression} is a pattern that describes a set of strings. Regular expressions are constructed analogously to arithmetic expressions, by using various operators to combine smaller expressions. @command{grep} understands two different versions of regular expression -syntax: ``basic'' and ``extended''. In @sc{gnu} @command{grep}, there is no -difference in available functionality using either syntax. +syntax: ``basic''(BRE) and ``extended''(ERE). In @sc{gnu} @command{grep}, +there is no difference in available functionality using either syntax. In other implementations, basic regular expressions are less powerful. The following description applies to extended regular expressions; differences for basic regular expressions are summarized afterwards. @@ -602,17 +716,92 @@ The fundamental building blocks are the regular expressions that match a single character. Most characters, including all letters and digits, are regular expressions that match themselves. Any metacharacter with special meaning may be quoted by preceding it with a backslash. -A list of characters enclosed by @samp{[} and @samp{]} matches any -single character in that list; if the first character of the list is the -caret @samp{^}, then it -matches any character @strong{not} in the list. For example, the regular -expression @samp{[0123456789]} matches any single digit. -A range of characters may be specified by giving the first -and last characters, separated by a hyphen. - -Finally, certain named classes of characters are predefined, as follows. + +A regular expression may be followed by one of several +repetition operators: + +@table @samp + +@item . +@opindex . +@cindex dot +@cindex period +The period @samp{.} matches any single character. + +@item ? +@opindex ? +@cindex question mark +@cindex match sub-expression at most once +The preceding item is optional and will be matched at most once. + +@item * +@opindex * +@cindex asterisk +@cindex match sub-expression zero or more times +The preceding item will be matched zero or more times. + +@item + +@opindex + +@cindex plus sign +The preceding item will be matched one or more times. + +@item @{@var{n}@} +@opindex @{n@} +@cindex braces, one argument +@cindex match sub-expression n times +The preceding item is matched exactly @var{n} times. + +@item @{@var{n},@} +@opindex @{n,@} +@cindex braces, second argument omitted +@cindex match sub-expression n or more times +The preceding item is matched n or more times. + +@item @{@var{n},@var{m}@} +@opindex @{n,m@} +@cindex braces, two arguments +The preceding item is matched at least @var{n} times, but not more than +@var{m} times. + +@end table + +Two regular expressions may be concatenated; the resulting regular +expression matches any string formed by concatenating two substrings +that respectively match the concatenated subexpressions. + +Two regular expressions may be joined by the infix operator @samp{|}; the +resulting regular expression matches any string matching either subexpression. + +Repetition takes precedence over concatenation, which in turn +takes precedence over alternation. A whole subexpression may be +enclosed in parentheses to override these precedence rules. + +@section Character Class + +@cindex bracket expression +@cindex character class +A @dfn{bracket expression} is a list of characters enclosed by @samp{[} and +@samp{]}. It matches any single character in that list; if the first +character of the list is the caret @samp{^}, then it matches any character +@strong{not} in the list. For example, the regular expression +@samp{[0123456789]} matches any single digit. + +@cindex range expression +Within a bracket expression, a @dfn{range expression} consists of two +characters separated by a hyphen. It matches any single character that +sorts between the two characters, inclusive, using the locale's +collating sequence and character set. For example, in the default C +locale, @samp{[a-d]} is equivalent to @samp{[abcd]}. Many locales sort +characters in dictionary order, and in these locales @samp{[a-d]} is +typically not equivalent to @samp{[abcd]}; it might be equivalent to +@samp{[aBbCcDd]}, for example. To obtain the traditional interpretation +of bracket expressions, you can use the C locale by setting the +@env{LC_ALL} environment variable to the value @samp{C}. + +Finally, certain named classes of characters are predefined within +bracket expressions, as follows. Their interpretation depends on the @code{LC_CTYPE} locale; the -interpretation below is that of the @sc{posix} locale, which is the default +interpretation below is that of the C locale, which is the default if no @code{LC_CTYPE} locale is specified. @cindex classes of characters @@ -696,86 +885,100 @@ Hexadecimal digits: @end table For example, @samp{[[:alnum:]]} means @samp{[0-9A-Za-z]}, except the latter -depends upon the @sc{posix} locale and the @sc{ascii} character +depends upon the C locale and the @sc{ascii} character encoding, whereas the former is independent of locale and character set. (Note that the brackets in these class names are part of the symbolic names, and must be included in addition to -the brackets delimiting the bracket list.) Most metacharacters lose -their special meaning inside lists. To include a literal @samp{]}, place it -first in the list. Similarly, to include a literal @samp{^}, place it anywhere -but first. Finally, to include a literal @samp{-}, place it last. +the brackets delimiting the bracket list.) -The period @samp{.} matches any single character. The symbol @samp{\w} -is a synonym for @samp{[[:alnum:]]} and @samp{\W} is a synonym for -@samp{[^[:alnum]]}. +Most metacharacters lose their special meaning inside lists. -The caret @samp{^} and the dollar sign @samp{$} are metacharacters that -respectively match the empty string at the beginning and end -of a line. The symbols @samp{\<} and @samp{\>} respectively match the -empty string at the beginning and end of a word. The symbol -@samp{\b} matches the empty string at the edge of a word, and @samp{\B} -matches the empty string provided it's not at the edge of a word. +@table @samp +@item ] +ends the list if it's not the first list item. So, if you want to make +the @samp{]} character a list item, you must put it first. -A regular expression may be followed by one of several -repetition operators: +@item [. +represents the open collating symbol. + +@item .] +represents the close collating symbol. + +@item [= +represents the open equivalence class. +@item =] +represents the close equivalence class. + +@item [: +represents the open character class followed by a valid character class name. + +@item :] +represents the close character class followed by a valid character class name. + +@item - +represents the range if it's not first or last in a list or the ending point +of a range. + +@item ^ +represents the characters not in the list. If you want to make the @samp{^} +character a list item, place it anywhere but first. + +@end table + +@section Backslash Character +@cindex backslash + +The @samp{\} when followed by certain ordinary characters take a special +meaning : @table @samp -@item ? -@opindex ? -@cindex question mark -@cindex match sub-expression at most once -The preceding item is optional and will be matched at most once. +@item @samp{\b} +Match the empty string at the edge of a word. -@item * -@opindex * -@cindex asterisk -@cindex match sub-expression zero or more times -The preceding item will be matched zero or more times. +@item @samp{\B} +Match the empty string provided it's not at the edge of a word. -@item + -@opindex + -@cindex plus sign -The preceding item will be matched one or more times. +@item @samp{\<} +Match the empty string at the beginning of word. -@item @{@var{n}@} -@opindex @{n@} -@cindex braces, one argument -@cindex match sub-expression n times -The preceding item is matched exactly @var{n} times. +@item @samp{\>} +Match the empty string at the end of word. -@item @{@var{n},@} -@opindex @{n,@} -@cindex braces, second argument omitted -@cindex match sub-expression n or more times -The preceding item is matched n or more times. +@item @samp{\w} +Match word constituent, it is a synonym for @samp{[[:alnum:]]}. -@item @{@var{n},@var{m}@} -@opindex @{n,m@} -@cindex braces, two arguments -The preceding item is matched at least @var{n} times, but not more than -@var{m} times. +@item @samp{\W} +Match non word constituent, it is a synonym for @samp{[^[:alnum:]]}. @end table -Two regular expressions may be concatenated; the resulting regular -expression matches any string formed by concatenating two substrings -that respectively match the concatenated subexpressions. +For example , @samp{\brat\b} matches the separate word @samp{rat}, +@samp{c\Brat\Be} matches @samp{crate}, but @samp{dirty \Brat} doesn't +match @samp{dirty rat}. -Two regular expressions may be joined by the infix operator @samp{|}; the -resulting regular expression matches any string matching either -subexpression. +@section Anchoring +@cindex anchoring -Repetition takes precedence over concatenation, which in turn -takes precedence over alternation. A whole subexpression may be -enclosed in parentheses to override these precedence rules. +The caret @samp{^} and the dollar sign @samp{$} are metacharacters that +respectively match the empty string at the beginning and end of a line. + +@section Back-reference +@cindex back-reference -The backreference @samp{\@var{n}}, where @var{n} is a single digit, matches the -substring previously matched by the @var{n}th parenthesized subexpression -of the regular expression. +The back-reference @samp{\@var{n}}, where @var{n} is a single digit, matches +the substring previously matched by the @var{n}th parenthesized subexpression +of the regular expression. For example, @samp{(a)\1} matches @samp{aa}. +When use with alternation if the group does not participate in the match, then +the back-reference makes the whole match fail. For example, @samp{a(.)|b\1} +will not match @samp{ba}. When multiple regular expressions are given with +@samp{-e} or from a file @samp{-f file}, the back-referecences are local to +each expression. +@section Basic vs Extended @cindex basic regular expressions + In basic regular expressions the metacharacters @samp{?}, @samp{+}, @samp{@{}, @samp{|}, @samp{(}, and @samp{)} lose their special meaning; instead use the backslashed versions @samp{\?}, @samp{\+}, @samp{\@{}, @@ -825,7 +1028,7 @@ How can I list just the names of matching files? @example grep -l 'main' *.c -@end example +@end example @noindent lists the names of all C files in the current directory whose contents @@ -848,12 +1051,23 @@ the following command searches only C files: find /home/gigi -name '*.c' -print | xargs grep 'hello' /dev/null @end smallexample +This differs from the command: + +@example +grep -r 'hello' *.c +@end example + +which merely looks for @samp{hello} in all files in the current +directory whose names end in @samp{.c}. Here the @option{-r} is +probably unnecessary, as recursion occurs only in the unlikely event +that one of @samp{.c} files is a directory. + @item What if a pattern has a leading @samp{-}? @example grep -e '--cut here--' * -@end example +@end example @noindent searches for all lines matching @samp{--cut here--}. Without @samp{-e}, @@ -899,6 +1113,12 @@ Append @file{/dev/null}: grep 'eli' /etc/passwd /dev/null @end example +gets you: + +@smallexample +/etc/passwd:eli:DNGUTF58.IMe.:98:11:Eli Smith:/home/do/eli:/bin/bash +@end smallexample + @item Why do people use strange regular expressions on @command{ps} output? @@ -909,6 +1129,9 @@ ps -ef | grep '[c]ron' If the pattern had been written without the square brackets, it would have matched not only the @command{ps} output line for @command{cron}, but also the @command{ps} output line for @command{grep}. +Note that some platforms @command{ps} limit the ouput to the width +of the screen, grep does not have any limit on the length of a line +except the available memory. @item Why does @command{grep} report ``Binary file matches''? @@ -948,23 +1171,905 @@ Use the special file name @samp{-}: @example cat /etc/passwd | grep 'alain' - /etc/motd @end example + +@item +@cindex palindromes +How to express palindromes in a regular expression? + +It can be done by using the back referecences, for example a palindrome +of 4 chararcters can be written in BRE. + +@example +grep -w -e '\(.\)\(.\).\2\1' file +@end example + +It matches the word "radar" or "civic". + +Guglielmo Bondioni proposed a single RE that finds all the palindromes up to 19 +characters long. + +@example +egrep -e '^(.?)(.?)(.?)(.?)(.?)(.?)(.?)(.?)(.?).?\9\8\7\6\5\4\3\2\1$' file +@end example + +Note this is done by using GNU ERE extensions, it might not be portable on +other greps. + +@item +Why are my expressions whith the vertical bar fail? + +@example +/bin/echo "ba" | egrep '(a)\1|(b)\1' +@end example + +The first alternate branch fails then the first group was not in the match +this will make the second alternate branch fails. For example, "aaba" will +match, the first group participate in the match and can be reuse in the +second branch. + +@item +What do @command{grep, fgrep, egrep} stand for ? + +grep comes from the way line editing was done on Unix. For example, +@command{ed} uses this syntax to print a list of matching lines on the screen. + +@example +global/regular expression/print +g/re/p +@end example + +@command{fgrep} stands for Fixed @command{grep}, @command{egrep} Extended +@command{grep}. + @end enumerate -@node Reporting Bugs +@node Reporting Bugs, Copying, Usage, Top @chapter Reporting bugs @cindex Bugs, reporting Email bug reports to @email{bug-gnu-utils@@gnu.org}. Be sure to include the word ``grep'' somewhere in the ``Subject:'' field. -Large repetition counts in the @samp{@{m,n@}} construct may cause +Large repetition counts in the @samp{@{n,m@}} construct may cause @command{grep} to use lots of memory. In addition, certain other obscure regular expressions require exponential time and space, and may cause grep to run out of memory. -Backreferences are very slow, and may require exponential time. +Back-references are very slow, and may require exponential time. + +@node Copying, GNU General Public License, Reporting Bugs, Top +@chapter Copying +@cindex Copying +GNU grep is licensed under the GNU GPL, which makes it @dfn{free +software}. + +Please note that ``free'' in ``free software'' refers to liberty, not +price. As some GNU project advocates like to point out, think of ``free +speech'' rather than ``free beer''. The exact and legally binding +distribution terms are spelled out below; in short, you have the right +(freedom) to run and change grep and distribute it to other people, and +even---if you want---charge money for doing either. The important +restriction is that you have to grant your recipients the same rights +and impose the same restrictions. + +This method of licensing software is also known as @dfn{open source} +because, among other things, it makes sure that all recipients will +receive the source code along with the program, and be able to improve +it. The GNU project prefers the term ``free software'' for reasons +outlined at +@url{http://www.gnu.org/philosophy/free-software-for-freedom.html}. + +The exact license terms are defined by this paragraph and the GNU +General Public License it refers to: + +@quotation +GNU grep 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 2 of the License, or (at your +option) any later version. + +GNU grep 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. + +A copy of the GNU General Public License is included as part of this +manual; if you did not receive it, write to the Free Software +Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. +@end quotation + +In addition to this, this manual is free in the same sense: + +@quotation +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.1 or +any later version published by the Free Software Foundation; with the +Invariant Sections being ``GNU General Public License'' and ``GNU Free +Documentation License'', with no Front-Cover Texts, and with no +Back-Cover Texts. A copy of the license is included in the section +entitled ``GNU Free Documentation License''. +@end quotation + +@c #### Maybe we should wrap these licenses in ifinfo? Stallman says +@c that the GFDL needs to be present in the manual, and to me it would +@c suck to include the license for the manual and not the license for +@c the program. + +The full texts of the GNU General Public License and of the GNU Free +Documentation License are available below. + +@menu +* GNU General Public License:: GNU GPL +* GNU Free Documentation License:: GNU FDL +@end menu + +@node GNU General Public License, GNU Free Documentation License, Copying, Copying +@section GNU General Public License +@center Version 2, June 1991 +@cindex GPL, GNU General Public License + +@display +Copyright @copyright{} 1989, 1991 Free Software Foundation, Inc. +675 Mass Ave, Cambridge, MA 02139, USA + +Everyone is permitted to copy and distribute verbatim copies +of this license document, but changing it is not allowed. +@end display + +@unnumberedsec Preamble + + The licenses for most software are designed to take away your +freedom to share and change it. By contrast, the GNU General Public +License is intended to guarantee your freedom to share and change free +software---to make sure the software is free for all its users. This +General Public License applies to most of the Free Software +Foundation's software and to any other program whose authors commit to +using it. (Some other Free Software Foundation software is covered by +the GNU Library General Public License instead.) You can apply it to +your programs, too. + + When we speak of free software, we are referring to freedom, not +price. Our General Public Licenses are designed to make sure that you +have the freedom to distribute copies of free software (and charge for +this service if you wish), that you receive source code or can get it +if you want it, that you can change the software or use pieces of it +in new free programs; and that you know you can do these things. + + To protect your rights, we need to make restrictions that forbid +anyone to deny you these rights or to ask you to surrender the rights. +These restrictions translate to certain responsibilities for you if you +distribute copies of the software, or if you modify it. + + For example, if you distribute copies of such a program, whether +gratis or for a fee, you must give the recipients all the rights that +you have. You must make sure that they, too, receive or can get the +source code. And you must show them these terms so they know their +rights. + + We protect your rights with two steps: (1) copyright the software, and +(2) offer you this license which gives you legal permission to copy, +distribute and/or modify the software. + + Also, for each author's protection and ours, we want to make certain +that everyone understands that there is no warranty for this free +software. If the software is modified by someone else and passed on, we +want its recipients to know that what they have is not the original, so +that any problems introduced by others will not reflect on the original +authors' reputations. + + Finally, any free program is threatened constantly by software +patents. We wish to avoid the danger that redistributors of a free +program will individually obtain patent licenses, in effect making the +program proprietary. To prevent this, we have made it clear that any +patent must be licensed for everyone's free use or not licensed at all. + + The precise terms and conditions for copying, distribution and +modification follow. + +@iftex +@unnumberedsec TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION +@end iftex +@ifinfo +@center TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION +@end ifinfo + +@enumerate +@item +This License applies to any program or other work which contains +a notice placed by the copyright holder saying it may be distributed +under the terms of this General Public License. The ``Program'', below, +refers to any such program or work, and a ``work based on the Program'' +means either the Program or any derivative work under copyright law: +that is to say, a work containing the Program or a portion of it, +either verbatim or with modifications and/or translated into another +language. (Hereinafter, translation is included without limitation in +the term ``modification''.) Each licensee is addressed as ``you''. + +Activities other than copying, distribution and modification are not +covered by this License; they are outside its scope. The act of +running the Program is not restricted, and the output from the Program +is covered only if its contents constitute a work based on the +Program (independent of having been made by running the Program). +Whether that is true depends on what the Program does. + +@item +You may copy and distribute verbatim copies of the Program's +source code as you receive it, in any medium, provided that you +conspicuously and appropriately publish on each copy an appropriate +copyright notice and disclaimer of warranty; keep intact all the +notices that refer to this License and to the absence of any warranty; +and give any other recipients of the Program a copy of this License +along with the Program. + +You may charge a fee for the physical act of transferring a copy, and +you may at your option offer warranty protection in exchange for a fee. + +@item +You may modify your copy or copies of the Program or any portion +of it, thus forming a work based on the Program, and copy and +distribute such modifications or work under the terms of Section 1 +above, provided that you also meet all of these conditions: + +@enumerate a +@item +You must cause the modified files to carry prominent notices +stating that you changed the files and the date of any change. + +@item +You must cause any work that you distribute or publish, that in +whole or in part contains or is derived from the Program or any +part thereof, to be licensed as a whole at no charge to all third +parties under the terms of this License. + +@item +If the modified program normally reads commands interactively +when run, you must cause it, when started running for such +interactive use in the most ordinary way, to print or display an +announcement including an appropriate copyright notice and a +notice that there is no warranty (or else, saying that you provide +a warranty) and that users may redistribute the program under +these conditions, and telling the user how to view a copy of this +License. (Exception: if the Program itself is interactive but +does not normally print such an announcement, your work based on +the Program is not required to print an announcement.) +@end enumerate + +These requirements apply to the modified work as a whole. If +identifiable sections of that work are not derived from the Program, +and can be reasonably considered independent and separate works in +themselves, then this License, and its terms, do not apply to those +sections when you distribute them as separate works. But when you +distribute the same sections as part of a whole which is a work based +on the Program, the distribution of the whole must be on the terms of +this License, whose permissions for other licensees extend to the +entire whole, and thus to each and every part regardless of who wrote it. + +Thus, it is not the intent of this section to claim rights or contest +your rights to work written entirely by you; rather, the intent is to +exercise the right to control the distribution of derivative or +collective works based on the Program. + +In addition, mere aggregation of another work not based on the Program +with the Program (or with a work based on the Program) on a volume of +a storage or distribution medium does not bring the other work under +the scope of this License. + +@item +You may copy and distribute the Program (or a work based on it, +under Section 2) in object code or executable form under the terms of +Sections 1 and 2 above provided that you also do one of the following: + +@enumerate a +@item +Accompany it with the complete corresponding machine-readable +source code, which must be distributed under the terms of Sections +1 and 2 above on a medium customarily used for software interchange; or, + +@item +Accompany it with a written offer, valid for at least three +years, to give any third party, for a charge no more than your +cost of physically performing source distribution, a complete +machine-readable copy of the corresponding source code, to be +distributed under the terms of Sections 1 and 2 above on a medium +customarily used for software interchange; or, + +@item +Accompany it with the information you received as to the offer +to distribute corresponding source code. (This alternative is +allowed only for noncommercial distribution and only if you +received the program in object code or executable form with such +an offer, in accord with Subsection b above.) +@end enumerate + +The source code for a work means the preferred form of the work for +making modifications to it. For an executable work, complete source +code means all the source code for all modules it contains, plus any +associated interface definition files, plus the scripts used to +control compilation and installation of the executable. However, as a +special exception, the source code distributed need not include +anything that is normally distributed (in either source or binary +form) with the major components (compiler, kernel, and so on) of the +operating system on which the executable runs, unless that component +itself accompanies the executable. + +If distribution of executable or object code is made by offering +access to copy from a designated place, then offering equivalent +access to copy the source code from the same place counts as +distribution of the source code, even though third parties are not +compelled to copy the source along with the object code. + +@item +You may not copy, modify, sublicense, or distribute the Program +except as expressly provided under this License. Any attempt +otherwise to copy, modify, sublicense or distribute the Program is +void, and will automatically terminate your rights under this License. +However, parties who have received copies, or rights, from you under +this License will not have their licenses terminated so long as such +parties remain in full compliance. + +@item +You are not required to accept this License, since you have not +signed it. However, nothing else grants you permission to modify or +distribute the Program or its derivative works. These actions are +prohibited by law if you do not accept this License. Therefore, by +modifying or distributing the Program (or any work based on the +Program), you indicate your acceptance of this License to do so, and +all its terms and conditions for copying, distributing or modifying +the Program or works based on it. + +@item +Each time you redistribute the Program (or any work based on the +Program), the recipient automatically receives a license from the +original licensor to copy, distribute or modify the Program subject to +these terms and conditions. You may not impose any further +restrictions on the recipients' exercise of the rights granted herein. +You are not responsible for enforcing compliance by third parties to +this License. + +@item +If, as a consequence of a court judgment or allegation of patent +infringement or for any other reason (not limited to patent issues), +conditions are imposed on you (whether by court order, agreement or +otherwise) that contradict the conditions of this License, they do not +excuse you from the conditions of this License. If you cannot +distribute so as to satisfy simultaneously your obligations under this +License and any other pertinent obligations, then as a consequence you +may not distribute the Program at all. For example, if a patent +license would not permit royalty-free redistribution of the Program by +all those who receive copies directly or indirectly through you, then +the only way you could satisfy both it and this License would be to +refrain entirely from distribution of the Program. + +If any portion of this section is held invalid or unenforceable under +any particular circumstance, the balance of the section is intended to +apply and the section as a whole is intended to apply in other +circumstances. + +It is not the purpose of this section to induce you to infringe any +patents or other property right claims or to contest validity of any +such claims; this section has the sole purpose of protecting the +integrity of the free software distribution system, which is +implemented by public license practices. Many people have made +generous contributions to the wide range of software distributed +through that system in reliance on consistent application of that +system; it is up to the author/donor to decide if he or she is willing +to distribute software through any other system and a licensee cannot +impose that choice. + +This section is intended to make thoroughly clear what is believed to +be a consequence of the rest of this License. + +@item +If the distribution and/or use of the Program is restricted in +certain countries either by patents or by copyrighted interfaces, the +original copyright holder who places the Program under this License +may add an explicit geographical distribution limitation excluding +those countries, so that distribution is permitted only in or among +countries not thus excluded. In such case, this License incorporates +the limitation as if written in the body of this License. + +@item +The Free Software Foundation may publish revised and/or new versions +of the General Public 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. + +Each version is given a distinguishing version number. If the Program +specifies a version number of this License which applies to it and ``any +later version'', you have the option of following the terms and conditions +either of that version or of any later version published by the Free +Software Foundation. If the Program does not specify a version number of +this License, you may choose any version ever published by the Free Software +Foundation. + +@item +If you wish to incorporate parts of the Program into other free +programs whose distribution conditions are different, write to the author +to ask for permission. For software which is copyrighted by the Free +Software Foundation, write to the Free Software Foundation; we sometimes +make exceptions for this. Our decision will be guided by the two goals +of preserving the free status of all derivatives of our free software and +of promoting the sharing and reuse of software generally. + +@iftex +@heading NO WARRANTY +@end iftex +@ifinfo +@center NO WARRANTY +@end ifinfo +@cindex no warranty + +@item +BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY +FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN +OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES +PROVIDE THE PROGRAM ``AS IS'' WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED +OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF +MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS +TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE +PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, +REPAIR OR CORRECTION. + +@item +IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING +WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR +REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, +INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING +OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED +TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY +YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER +PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE +POSSIBILITY OF SUCH DAMAGES. +@end enumerate + +@iftex +@heading END OF TERMS AND CONDITIONS +@end iftex +@ifinfo +@center END OF TERMS AND CONDITIONS +@end ifinfo + +@page +@unnumberedsec How to Apply These Terms to Your New Programs + + If you develop a new program, and you want it to be of the greatest +possible use to the public, the best way to achieve this is to make it +free software which everyone can redistribute and change under these terms. + + To do so, attach the following notices to the program. It is safest +to attach them to the start of each source file to most effectively +convey the exclusion of warranty; and each file should have at least +the ``copyright'' line and a pointer to where the full notice is found. + +@smallexample +@var{one line to give the program's name and an idea of what it does.} +Copyright (C) 19@var{yy} @var{name of author} + +This program 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 2 +of the License, or (at your option) any later version. + +This program 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 this program; if not, write to the Free Software +Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. +@end smallexample + +Also add information on how to contact you by electronic and paper mail. + +If the program is interactive, make it output a short notice like this +when it starts in an interactive mode: + +@smallexample +Gnomovision version 69, Copyright (C) 19@var{yy} @var{name of author} +Gnomovision comes with ABSOLUTELY NO WARRANTY; for details +type `show w'. This is free software, and you are welcome +to redistribute it under certain conditions; type `show c' +for details. +@end smallexample + +The hypothetical commands @samp{show w} and @samp{show c} should show +the appropriate parts of the General Public License. Of course, the +commands you use may be called something other than @samp{show w} and +@samp{show c}; they could even be mouse-clicks or menu items---whatever +suits your program. + +You should also get your employer (if you work as a programmer) or your +school, if any, to sign a ``copyright disclaimer'' for the program, if +necessary. Here is a sample; alter the names: + +@smallexample +@group +Yoyodyne, Inc., hereby disclaims all copyright +interest in the program `Gnomovision' +(which makes passes at compilers) written +by James Hacker. + +@var{signature of Ty Coon}, 1 April 1989 +Ty Coon, President of Vice +@end group +@end smallexample + +This General Public License does not permit incorporating your program into +proprietary programs. If your program is a subroutine library, you may +consider it more useful to permit linking proprietary applications with the +library. If this is what you want to do, use the GNU Library General +Public License instead of this License. + +@node GNU Free Documentation License, Concept Index, GNU General Public License, Copying +@section GNU Free Documentation License +@center Version 1.1, March 2000 +@cindex FDL, GNU Free Documentation License + +@display +Copyright (C) 2000 Free Software Foundation, Inc. +59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + +Everyone is permitted to copy and distribute verbatim copies +of this license document, but changing it is not allowed. +@end display +@sp 1 +@enumerate 0 +@item +PREAMBLE + +The purpose of this License is to make a manual, textbook, or other +written document ``free'' 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. + +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. + +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. 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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.@* +G. Preserve in that license notice the full lists of Invariant Sections + and required Cover Texts given in the Document's license notice.@* +H. Include an unaltered copy of this License.@* +I. Preserve the section entitled ``History'', and 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.@* +J. 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.@* +K. In any section entitled ``Acknowledgements'' or ``Dedications'', + preserve the section's title, and preserve in the section all the + substance and tone of each of the contributor acknowledgements + and/or dedications given therein.@* +L. 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.@* +M. Delete any section entitled ``Endorsements''. Such a section + may not be included in the Modified Version.@* +N. Do not retitle any existing section as ``Endorsements'' + or to conflict in title with any Invariant Section.@* +@sp 1 +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. + +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. + +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. 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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. + +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.'' +@sp 1 +@item +COLLECTIONS OF DOCUMENTS + +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. + +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. +@sp 1 +@item +AGGREGATION WITH INDEPENDENT WORKS + +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, does not as a whole count as a Modified Version +of the Document, provided no compilation copyright is claimed for the +compilation. Such a compilation is called an ``aggregate'', and this +License does not apply to the other self-contained works thus compiled +with the Document, on account of their being thus compiled, if they +are not themselves derivative works of the Document. + +If the Cover Text requirement of section 3 is applicable to these +copies of the Document, then if the Document is less than one quarter +of the entire aggregate, the Document's Cover Texts may be placed on +covers that surround only the Document within the aggregate. +Otherwise they must appear on covers around the whole aggregate. +@sp 1 +@item +TRANSLATION + +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 provided that you also include the +original English version of this License. In case of a disagreement +between the translation and the original English version of this +License, the original English version will prevail. +@sp 1 +@item +TERMINATION + +You may not copy, modify, sublicense, or distribute the Document except +as expressly provided for under this License. Any other attempt to +copy, modify, sublicense or distribute the Document is void, and will +automatically terminate your rights under this License. However, +parties who have received copies, or rights, from you under this +License will not have their licenses terminated so long as such +parties remain in full compliance. +@sp 1 +@item +FUTURE REVISIONS OF THIS LICENSE + +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 +http://www.gnu.org/copyleft/. + +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. + +@end enumerate + +@unnumberedsec ADDENDUM: How to use this License for your documents + +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: + +@smallexample +@group + + Copyright (C) @var{year} @var{your name}. + Permission is granted to copy, distribute and/or modify this document + under the terms of the GNU Free Documentation License, Version 1.1 + or any later version published by the Free Software Foundation; + with the Invariant Sections being @var{list their titles}, with the + Front-Cover Texts being @var{list}, and with the Back-Cover Texts being @var{list}. + A copy of the license is included in the section entitled ``GNU + Free Documentation License''. +@end group +@end smallexample +If you have no Invariant Sections, write ``with no Invariant Sections'' +instead of saying which ones are invariant. If you have no +Front-Cover Texts, write ``no Front-Cover Texts'' instead of +``Front-Cover Texts being @var{list}''; likewise for Back-Cover Texts. + +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. @page -@node Concept Index +@node Concept Index, Index, GNU Free Documentation License, Top @unnumbered Concept Index This is a general index of all issues discussed in this manual, with the @@ -973,7 +2078,7 @@ exception of the @command{grep} commands and command-line options. @printindex cp @page -@node Index +@node Index,, Concept Index, Top @unnumbered Index This is an alphabetical list of all @command{grep} commands, command-line |