GNU grep NEWS -*- outline -*- * Noteworthy changes in release 2.20 (2014-06-03) [stable] ** Bug fixes grep --max-count=N FILE would no longer stop reading after the Nth match. I.e., while grep would still print the correct output, it would continue reading until end of input, and hence, potentially forever. [bug introduced in grep-2.19] A command like echo aa|grep -E 'a(b$|c$)' would mistakenly report the input as a matched line. [bug introduced in grep-2.19] ** Changes in behavior grep --exclude-dir='FOO/' now excludes the directory FOO. Previously, the trailing slash meant the option was ineffective. * Noteworthy changes in release 2.19 (2014-05-22) [stable] ** Improvements Performance has improved, typically by 10% and in some cases by a factor of 200. However, performance of grep -P in UTF-8 locales has gotten worse as part of the fix for the crashes mentioned below. ** Bug fixes grep no longer mishandles patterns like [a-[.z.]], and no longer mishandles patterns like [^a] in locales that have multicharacter collating sequences so that [^a] can match a string of two characters. grep no longer mishandles an empty pattern at the end of a pattern list. [bug introduced in grep-2.5] grep -C NUM now outputs separators consistently even when NUM is zero, and similarly for grep -A NUM and grep -B NUM. [bug present since "the beginning"] grep -f no longer mishandles patterns containing NUL bytes. [bug introduced in grep-2.11] Plain grep, grep -E, and grep -F now treat encoding errors in patterns the same way the GNU regular expression matcher treats them, with respect to whether the errors can match parts of multibyte characters in data. [bug present since "the beginning"] grep -w no longer mishandles a potential match adjacent to a letter that takes up two or more bytes in a multibyte encoding. Similarly, the patterns '\<', '\>', '\b', and '\B' no longer mishandle word-boundary matches in multibyte locales. [bug present since "the beginning"] grep -P now reports an error and exits when given invalid UTF-8 data. Previously it was unreliable, and sometimes crashed or looped. [bug introduced in grep-2.16] grep -P now works with -w and -x and backreferences. Before, echo aa|grep -Pw '(.)\1' would fail to match, yet echo aa|grep -Pw '(.)\2' would match. grep -Pw now works like grep -w in that the matched string has to be preceded and followed by non-word components or the beginning and end of the line (as opposed to word boundaries before). Before, this echo a@@a| grep -Pw @@ would match, yet this echo a@@a| grep -w @@ would not. Now, they both fail to match, per the documentation on how grep's -w works. grep -i no longer mishandles patterns containing titlecase characters. For example, in a locale containing the titlecase character 'Lj' (U+01C8 LATIN CAPITAL LETTER L WITH SMALL LETTER J), 'grep -i Lj' now matches both 'LJ' (U+01C7 LATIN CAPITAL LETTER LJ) and 'lj' (U+01C9 LATIN SMALL LETTER LJ). * Noteworthy changes in release 2.18 (2014-02-20) [stable] ** Bug fixes grep no longer mishandles patterns like [^^-~] in unibyte locales. [bug introduced in grep-2.8] grep -i in a multibyte, non-UTF8 locale could be up to 200 times slower than in 2.16. [bug introduced in grep-2.17] * Noteworthy changes in release 2.17 (2014-02-17) [stable] ** Improvements grep -i in a multibyte locale is now typically 10 times faster for patterns that do not contain \ or [. grep (without -i) in a multibyte locale is now up to 7 times faster when processing many matched lines. ** Maintenance grep's --mmap option was disabled in March of 2010, and began to elicit a warning in January of 2012. Now it is completely gone. * Noteworthy changes in release 2.16 (2014-01-01) [stable] ** Bug fixes Fix gnulib-provided maint.mk so that the release procedure described in README-release actually does what we want. Before that fix, that procedure resulted in a grep-2.15 tarball that would lead to a grep binary whose --version-reported version number was 2.14.51... The fix to make \s and \S work with multi-byte white space broke the use of each shortcut whenever followed by a repetition operator. For example, \s*, \s+, \s? and \s{3} would all malfunction in a multi-byte locale. [bug introduced in grep-2.15] The fix to make grep -P work better with UTF-8 made it possible for grep to evoke a larger set of PCRE errors, some of which could trigger an abort. E.g., this would abort: printf '\x82'|LC_ALL=en_US.UTF-8 grep -P y Now grep handles arbitrary PCRE errors. [bug introduced in grep-2.15] Handle very long lines (2GiB and longer) on systems with a deficient read system call. * Noteworthy changes in release 2.15 (2013-10-26) [stable] ** Bug fixes grep's \s and \S failed to work with multi-byte white space characters. For example, \s would fail to match a non-breaking space, and this would print nothing: printf '\xc2\xa0' | LC_ALL=en_US.UTF-8 grep '\s' A related bug is that \S would mistakenly match an invalid multibyte character. For example, the following would match: printf '\x82\n' | LC_ALL=en_US.UTF-8 grep '^\S$' [bug present since grep-2.6] grep -i would segfault on systems using UTF-16-based wchar_t (Cygwin) when converting an input string containing certain 4-byte UTF-8 sequences to lower case. The conversions to wchar_t and back to a UTF-8 multibyte string did not take surrogate pairs into account. [bug present since at least grep-2.6, though the segfault is new with 2.13] grep -E would segfault when given a regexp like '([^.]*[M]){1,2}' for any multibyte character M. [bug introduced in grep-2.6, which would segfault, but 2.7 and 2.8 had no problem, and 2.9 through 2.14 would hit a failed assertion. ] grep -F would get stuck in an infinite loop when given a search string that is an invalid byte sequence in the current locale and that matches the bytes of the input twice on a line. Now grep fails with exit status 1. grep -P could misbehave. While multi-byte mode is only supported by PCRE with UTF-8 locales, grep did not activate it. This would cause failures to match multibyte characters against some regular expressions, especially those including the '.' or '\p' metacharacters. ** New features grep -P can now use a just-in-time compiler to greatly speed up matches, This feature is transparent to the user; no flag is required to enable it. It is only available if the corresponding support in the PCRE library is detected when grep is compiled. * Noteworthy changes in release 2.14 (2012-08-20) [stable] ** Bug fixes grep -i '^$' could exit 0 (i.e., report a match) in a multi-byte locale, even though there was no match, and the command generated no output. E.g., seq 2 | LC_ALL=en_US.utf8 grep -il '^$' would mistakenly print "(standard input)". Related, seq 9 | LC_ALL=en_US.utf8 grep -in '^$' would print "2:4:6:8:10:12:14:16" and exit 0. Now it prints nothing and exits with status of 1. [bug introduced in grep-2.6] 'grep' no longer falsely reports text files as being binary on file systems that compress contents or that store tiny contents in metadata. * Noteworthy changes in release 2.13 (2012-07-04) [stable] ** Bug fixes grep -i, in a multi-byte locale, when matching a line containing a character like the UTF-8 Turkish I-with-dot (U+0130) (whose lower-case representation occupies fewer bytes), would print an incomplete output line. Similarly, with a matched line containing a character (e.g., the Latin capital I in a Turkish UTF-8 locale), where the lower-case representation occupies more bytes, grep could print garbage. [bug introduced in grep-2.6] --include and --exclude can again be combined, and again apply to the command line, e.g., "grep --include='*.[ch]' --exclude='system.h' PATTERN *" again reads all *.c and *.h files except for system.h. [bug introduced in grep-2.6] ** New features 'grep' without -z now treats a sparse file as binary, if it can easily determine that the file is sparse. ** Dropped features Bootstrapping with Makefile.boot has been broken since grep 2.6, and was removed. * Noteworthy changes in release 2.12 (2012-04-23) [stable] ** Bug fixes "echo P|grep --devices=skip P" once again prints P, as it did in 2.10 [bug introduced in grep-2.11] grep no longer segfaults with -r --exclude-dir and no file operand. I.e., ":|grep -r --exclude-dir=D PAT" would segfault. [bug introduced in grep-2.11] Recursive grep now uses fts for directory traversal, so it can handle much-larger directories without reporting things like "File name too long", and it can run much faster when dealing with large directory hierarchies. [bug present since the beginning] grep -E 'a{1000000000}' now reports an overflow error rather than silently acting like grep -E 'a\{1000000000}'. grep -E 'a{,10}' was not treated equivalently to grep -E 'a{0,10}'. ** New features The -R option now has a long-option alias --dereference-recursive. ** Changes in behavior The -r (--recursive) option now follows only command-line symlinks. Also, by default -r now reads a device only if it is named on the command line; this can be overridden with --devices. -R acts as before, so use -R if you prefer the old behavior of following all symlinks and defaulting to reading all devices. * Noteworthy changes in release 2.11 (2012-03-02) [stable] ** Bug fixes grep no longer dumps core on lines whose lengths do not fit in 'int'. (e.g., lines longer than 2 GiB on a typical 64-bit host). Instead, grep either works as expected, or reports an error. An error can occur if not enough main memory is available, or if the GNU C library's regular expression functions cannot handle such long lines. [bug present since "the beginning"] The -m, -A, -B, and -C options no longer mishandle context line counts that do not fit in 'int'. Also, grep -c's counts are now limited by the type 'intmax_t' (typically less than 2**63) rather than 'int' (typically less than 2**31). grep no longer silently suppresses errors when reading a directory as if it were a text file. For example, "grep x ." now reports a read error on most systems; formerly, it ignored the error. [bug introduced in grep-2.5] grep now exits with status 2 if a directory loop is found, instead of possibly exiting with status 0 or 1. [bug introduced in grep-2.3] The -s option now suppresses certain input error diagnostics that it formerly failed to suppress. These include errors when closing the input, when lseeking the input, and when the input is also the output. [bug introduced in grep-2.4] On POSIX systems, commands like "grep PAT < FILE >> FILE" now report an error instead of looping. [bug present since "the beginning"] The --include, --exclude, and --exclude-dir options now handle command-line arguments more consistently. --include and --exclude apply only to non-directories and --exclude-dir applies only to directories. "-" (standard input) is never excluded, since it is not a file name. [bug introduced in grep-2.5] grep no longer rejects "grep -qr . > out", i.e., when run with -q and an input file is the same as the output file, since with -q grep generates no output, so there is no risk of infinite loop or of an output-affecting race condition. Thus, the use of the following options also disables the input-equals-output failure: --max-count=N (-m) (for N >= 2) --files-with-matches (-l) --files-without-match (-L) [bug introduced in grep-2.10] grep no longer emits an error message and quits on MS-Windows when invoked with the -r option. grep no longer misinterprets some alternations involving anchors (^, $, \< \> \B, \b). For example, grep -E "(^|\B)a" no longer reports a match for the string "x a". [bug present since "the beginning"] ** New features If no file operand is given, and a command-line -r or equivalent option is given, grep now searches the working directory. Formerly grep ignored the -r and searched standard input nonrecursively. An -r found in GREP_OPTIONS does not have this new effect. grep now supports color highlighting of matches on MS-Windows. ** Changes in behavior Use of the --mmap option now elicits a warning. It has been a no-op since March of 2010. grep no longer diagnoses write errors repeatedly; it exits after diagnosing the first write error. This is better behavior when writing to a dangling pipe. Syntax errors in GREP_COLORS are now ignored, instead of sometimes eliciting warnings. This is more consistent with programs that (e.g.) ignore errors in termcap entries. * Noteworthy changes in release 2.10 (2011-11-16) [stable] ** Bug fixes grep no longer mishandles high-bit-set pattern bytes on systems where "char" is a signed type. [bug appears to affect only MS-Windows] On POSIX systems, grep now rejects a command like "grep -r pattern . > out", in which the output file is also one of the inputs, because it can result in an "infinite" disk-filling loop. [bug present since "the beginning"] ** Build-related "make dist" no longer builds .tar.gz files. xz is portable enough and in wide-enough use that distributing only .tar.xz files is enough. * Noteworthy changes in release 2.9 (2011-06-21) [stable] ** Bug fixes grep no longer clobbers heap for an ERE like '(^| )*( |$)' [bug introduced in grep-2.6] grep is faster on regular expressions that match multibyte characters in brackets (such as '[áéíóú]'). echo c|grep '[c]' would fail for any c in 0x80..0xff, with a uni-byte encoding for which the byte-to-wide-char mapping is nontrivial. For example, the ISO-88591 locales are not affected, but ru_RU.KOI8-R is. [bug introduced in grep-2.6] grep -P no longer aborts when PCRE's backtracking limit is exceeded Before, echo aaaaaaaaaaaaaab |grep -P '((a+)*)+$' would abort. Now, it diagnoses the problem and exits with status 2. * Noteworthy changes in release 2.8 (2011-05-13) [stable] ** Bug fixes echo c|grep '[c]' would fail for any c in 0x80..0xff, and in many locales. E.g., printf '\xff\n'|grep "$(printf '[\xff]')" || echo FAIL would print FAIL rather than the required matching line. [bug introduced in grep-2.6] grep's interpretation of range expression is now more consistent with that of other tools. [bug present since multi-byte character set support was introduced in 2.5.2, though the steps needed to reproduce it changed in grep-2.6] grep erroneously returned with exit status 1 on some memory allocation failure. [bug present since "the beginning"] * Noteworthy changes in release 2.7 (2010-09-16) [stable] ** Bug fixes grep --include=FILE works once again, rather than working like --exclude=FILE [bug introduced in grep-2.6] Searching with grep -Fw for an empty string would not match an empty line. [bug present since "the beginning"] X{0,0} is implemented correctly. It used to be a synonym of X{0,1}. [bug present since "the beginning"] In multibyte locales, regular expressions including backreferences no longer exhibit quadratic complexity (i.e., they are orders of magnitude faster). [bug present since multi-byte character set support was introduced in 2.5.2] In UTF-8 locales, regular expressions including "." can be orders of magnitude faster. For example, "grep ." is now twice as fast as "grep -v ^$", instead of being immensely slower. It remains slow in other multibyte locales. [bug present since multi-byte character set support was introduced in 2.5.2] --mmap was meant to be ignored in 2.6.x, but it was instead removed by mistake. [bug introduced in 2.6] ** New features On systems using glibc, grep can support equivalence classes. However, whether they actually work depends on glibc's locale definitions. * Noteworthy changes in release 2.6.3 (2010-04-02) [stable] ** Bug fixes Searching with grep -F for an empty string in a multibyte locale would hang grep. [bug introduced in 2.6.2] PCRE support is once again detected on systems with [bug introduced in 2.6.2] * Noteworthy changes in release 2.6.2 (2010-03-29) [stable] ** Bug fixes grep -F no longer mistakenly reports a match when searching for an incomplete prefix of a multibyte character. [bug present since "the beginning"] grep -F no longer goes into an infinite loop when it finds a match for an incomplete (non-prefix of a) multibyte character. [bug introduced in 2.6] Using any of the --include or --exclude* options would cause a NULL dereference. [bugs introduced in 2.6] ** Build-related configure no longer relies on pkg-config to detect PCRE support. * Noteworthy changes in release 2.6.1 (2010-03-25) [stable] ** Bug fixes Character classes could cause a segmentation fault if they included a multibyte character. [bug introduced in 2.6] Character ranges would not work in single-byte character sets other than C (for example, ISO-8859-1 or KOI8-R) and some multi-byte locales. For example, this should print "1", but would find no match: $ echo 1 | env -i LC_COLLATE=en_US.UTF-8 grep '[0-9]' [bug introduced in 2.6] The output of grep was incorrect for whole-word (-w) matches if the patterns included a back-reference. [bug introduced in grep-2.5.2] ** Portability Avoid a link failure on Solaris 8. * Noteworthy changes in release 2.6 (2010-03-23) [stable] ** Speed improvements grep is much faster on multibyte character sets, especially (but not limited to) UTF-8 character sets. The speed improvement is also very pronounced with case-insensitive matches. ** Bug fixes Character classes would malfunction in multi-byte locales when using grep -i. Examples which would print nothing for LC_ALL=en_US.UTF-8 include: - for ranges, echo Z | grep -i '[a-z]' - for single characters, echo Y | grep -i '[y]' - for character types, echo Y | grep -i '[[:lower:]]' grep -i -o would fail to report some matches; grep -i --color, while not missing any line containing a match, would fail to color some matches. grep would fail to report a match in a multibyte character set other than UTF-8, if another match occurred earlier in the line but started in the middle of a multibyte character. Various bugs in grep -P, caused by expressions such as [^b] or \S matching newlines, were fixed. grep -P also supports the special sequences \Z and \z, and can be combined with the command-line option -z to perform searches on NUL-separated records. grep would mistakenly exit with status 1 upon error, rather than 2, as it is documented to do. Using options like -1 -2 or -1 -v -2 results in two lines of context (the last value that appears on the command line) instead twelve (the concatenation of all the values). This is consistent with the behavior of options -A/-B/-C. Two new command-line options, --group-separator=ARGUMENT and --no-group-separator, enable further customization of the output when -A, -B or -C is being used. ** Other changes egrep accepts the -E option and fgrep accepts the -F option. If egrep and fgrep are given another of the -E/-F/-G options, they print a more meaningful error message. * Noteworthy changes in release 2.5.4 (2009-02-10) [stable] - This is a bugfix release. No new features. Version 2.5.3 - The new option --exclude-dir allows to specify a directory pattern that will be excluded from recursive grep. - Numerous bug fixes Version 2.5.1 - This is a bugfix release. No new features. Version 2.5 - The new option --label allows to specify a different name for input from stdin. See the man or info pages for details. - The internal lib/getopt* files are no longer used on systems providing getopt functionality in their libc (e.g. glibc 2.2.x). If you need the old getopt files, use --with-included-getopt. - The new option --only-matching (-o) will print only the part of matching lines that matches the pattern. This is useful, for example, to extract IP addresses from log files. - i18n bug fixed ([A-Z0-9] wouldn't match A in locales other than C on systems using recent glibc builds - GNU grep can now be built with autoconf 2.52. - The new option --devices controls how grep handles device files. Its usage is analogous to --directories. - The new option --line-buffered fflush on everyline. There is a noticeable slow down when forcing line buffering. - Back references are now local to the regex. grep -e '\(a\)\1' -e '\(b\)\1' The last backref \1 in the second expression refer to \(b\) - The new option --include=PATTERN will search only matching files when recursing in directories - The new option --exclude=PATTERN will skip matching files when recursing in directories. - The new option --color will use the environment variable GREP_COLOR (default is red) to highlight the matching string. --color takes an optional argument specifying when to colorize a line: --color=always, --color=tty, --color=never - The following changes are for POSIX conformance: . The -q or --quiet or --silent option now causes grep to exit with zero status when a input line is selected, even if an error also occurs. . The -s or --no-messages option no longer affects the exit status. . Bracket regular expressions like [a-z] are now locale-dependent. For example, many locales sort characters in dictionary order, and in these locales the regular expression [a-d] is not equivalent to [abcd]; it might be equivalent to [aBbCcDd], for example. To obtain the traditional interpretation of bracket expressions, you can use the C locale by setting the LC_ALL environment variable to the value "C". - The -C or --context option now requires an argument, partly for consistency, and partly because POSIX recommends against optional arguments. - The new -P or --perl-regexp option tells grep to interpret the pattern as a Perl regular expression. - The new option --max-count=num makes grep stop reading a file after num matching lines. New option -m; equivalent to --max-count. - Translations for bg, ca, da, nb and tr have been added. Version 2.4.2 - Added more check in configure to default the grep-${version}/src/regex.c instead of the one in GNU Lib C. Version 2.4.1 - If the final byte of an input file is not a newline, grep now silently supplies one. - The new option --binary-files=TYPE makes grep assume that a binary input file is of type TYPE. --binary-files='binary' (the default) outputs a 1-line summary of matches. --binary-files='without-match' assumes binary files do not match. --binary-files='text' treats binary files as text (equivalent to the -a or --text option). - New option -I; equivalent to --binary-files='without-match'. Version 2.4: - egrep is now equivalent to 'grep -E' as required by POSIX, removing a longstanding source of confusion and incompatibility. 'grep' is now more forgiving about stray '{'s, for backward compatibility with traditional egrep. - The lower bound of an interval is not optional. You must use an explicit zero, e.g. 'x{0,10}' instead of 'x{,10}'. (The old documentation incorrectly claimed that it was optional.) - The --revert-match option has been renamed to --invert-match. - The --fixed-regexp option has been renamed to --fixed-string. - New option -H or --with-filename. - New option --mmap. By default, GNU grep now uses read instead of mmap. This is faster on some hosts, and is safer on all. - The new option -z or --null-data causes 'grep' to treat a zero byte (the ASCII NUL character) as a line terminator in input data, and to treat newlines as ordinary data. - The new option -Z or --null causes 'grep' to output a zero byte instead of the normal separator after a file name. - These two options can be used with commands like 'find -print0', 'perl -0', 'sort -z', and 'xargs -0' to process arbitrary file names, even those that contain newlines. - The environment variable GREP_OPTIONS specifies default options; e.g. GREP_OPTIONS='--directories=skip' reestablishes grep 2.1's behavior of silently skipping directories. - You can specify a matcher multiple times without error, e.g. 'grep -E -E' or 'fgrep -F'. It is still an error to specify conflicting matchers. - -u and -U are now allowed on non-DOS hosts, and have no effect. - Modifications of the tests scripts to go around the "Broken Pipe" errors from bash. See Bash FAQ. - New option -r or --recursive or --directories=recurse. (This option was also in grep 2.3, but wasn't announced here.) - --without-included-regex disable, was causing bogus reports .i.e doing more harm then good. Version 2.3: - When searching a binary file FOO, grep now just reports "Binary file FOO matches" instead of outputting binary data. This is typically more useful than the old behavior, and it is also more consistent with other utilities like 'diff'. A file is considered to be binary if it contains a NUL (i.e. zero) byte. The new -a or --text option causes 'grep' to assume that all input is text. (This option has the same meaning as with 'diff'.) Use it if you want binary data in your output. - 'grep' now searches directories just like ordinary files; it no longer silently skips directories. This is the traditional behavior of Unix text utilities (in particular, of traditional 'grep'). Hence 'grep PATTERN DIRECTORY' should report "grep: DIRECTORY: Is a directory" on hosts where the operating system does not permit programs to read directories directly, and "grep: DIRECTORY: Binary file matches" (or nothing) otherwise. The new -d ACTION or --directories=ACTION option affects directory handling. '-d skip' causes 'grep' to silently skip directories, as in grep 2.1; '-d read' (the default) causes 'grep' to read directories if possible, as in earlier versions of grep. - The MS-DOS and Microsoft Windows ports now behave identically to the GNU and Unix ports with respect to binary files and directories. Version 2.2: Bug fix release. - Status error number fix. - Skipping directories removed. - Many typos fix. - -f /dev/null fix(not to consider as an empty pattern). - Checks for wctype/wchar. - -E was using the wrong matcher fix. - bug in regex char class fix - Fixes for DJGPP Version 2.1: This is a bug fix release(see Changelog) i.e. no new features. - More compliance to GNU standard. - Long options. - Internationalization. - Use automake/autoconf. - Directory hierarchy change. - Sigvec with -e on Linux corrected. - Sigvec with -f on Linux corrected. - Sigvec with the mmap() corrected. - Bug in kwset corrected. - -q, -L and -l stop on first match. - New and improve regex.[ch] from Ulrich Drepper. - New and improve dfa.[ch] from Arnold Robbins. - Prototypes for over zealous C compiler. - Not scanning a file, if it's a directory (cause problems on Sun). - Ported to MS-DOS/MS-Windows with DJGPP tools. See Changelog for the full story and proper credits. Version 2.0: The most important user visible change is that egrep and fgrep have disappeared as separate programs into the single grep program mandated by POSIX 1003.2. New options -G, -E, and -F have been added, selecting grep, egrep, and fgrep behavior respectively. For compatibility with historical practice, hard links named egrep and fgrep are also provided. See the manual page for details. In addition, the regular expression facilities described in Posix draft 11.2 are now supported, except for internationalization features related to locale-dependent collating sequence information. There is a new option, -L, which is like -l except it lists files which don't contain matches. The reason this option was added is because '-l -v' doesn't do what you expect. Performance has been improved; the amount of improvement is platform dependent, but (for example) grep 2.0 typically runs at least 30% faster than grep 1.6 on a DECstation using the MIPS compiler. Where possible, grep now uses mmap() for file input; on a Sun 4 running SunOS 4.1 this may cut system time by as much as half, for a total reduction in running time by nearly 50%. On machines that don't use mmap(), the buffering code has been rewritten to choose more favorable alignments and buffer sizes for read(). Portability has been substantially cleaned up, and an automatic configure script is now provided. The internals have changed in ways too numerous to mention. People brave enough to reuse the DFA matcher in other programs will now have their bravery amply "rewarded", for the interface to that file has been completely changed. Some changes were necessary to track the evolution of the regex package, and since I was changing it anyway I decided to do a general cleanup. ======================================================================== Copyright (C) 1992, 1997-2002, 2004-2014 Free Software Foundation, Inc. Copying and distribution of this file, with or without modification, are permitted in any medium without royalty provided the copyright notice and this notice are preserved. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the "GNU Free Documentation License" file as part of this distribution.