PATCH(1) General Commands Manual PATCH(1) NAME patch - apply a diff file to an original SYNOPSIS patch [options] [originalfile [patchfile]] but usually just patch -pnum >>>>>> lines. A typical conflict will look like this: <<<<<<< lines from the original file ||||||| original lines from the patch ======= new lines from the patch >>>>>>> The optional argument of --merge determines the output format for conflicts: the diff3 format shows the ||||||| section with the original lines from the patch; in the merge format, this section is missing. The merge format is the default. This option implies --forward and does not take the --fuzz=num option into account. -n or --normal Interpret the patch file as a normal diff. -N or --forward When a patch does not apply, patch usually checks if the patch looks like it has been applied already by trying to reverse-apply the first hunk. The --forward option prevents that. See also -R. -o outfile or --output=outfile Send output to outfile instead of patching files in place. Do not use this option if outfile is one of the files to be patched. When outfile is -, send output to standard output, and send any messages that would usually go to standard output to standard error. -pnum or --strip=num Strip the smallest prefix containing num leading slashes from each file name found in the patch file. A sequence of one or more adjacent slashes is counted as a single slash. This controls how file names found in the patch file are treated, in case you keep your files in a different directory than the person who sent out the patch. For example, supposing the file name in the patch file was /u/howard/src/blurfl/blurfl.c setting -p0 gives the entire file name unmodified, -p1 gives u/howard/src/blurfl/blurfl.c without the leading slash, -p4 gives blurfl/blurfl.c and not specifying -p at all just gives you blurfl.c. Whatever you end up with is looked for either in the current directory, or the directory specified by the -d option. --posix Conform more strictly to the POSIX standard, as follows. o Take the first existing file from the list (old, new, index) when intuiting file names from diff headers. o Do not remove files that are empty after patching. o Do not ask whether to get files from RCS, ClearCase, Perforce, or SCCS. o Require that all options precede the files in the command line. o Do not backup files when there is a mismatch. --quoting-style=word Use style word to quote output names. The word should be one of the following: literal Output names as-is. shell Quote names for the shell if they contain shell metacharacters or would cause ambiguous output. shell-always Quote names for the shell, even if they would normally not require quoting. c Quote names as for a C language string. escape Quote as with c except omit the surrounding double-quote characters. You can specify the default value of the --quoting-style option with the environment variable QUOTING_STYLE. If that environment variable is not set, the default value is shell. -r rejectfile or --reject-file=rejectfile Put rejects into rejectfile instead of the default .rej file. When rejectfile is -, discard rejects. -R or --reverse Assume that this patch was created with the old and new files swapped. (Yes, I'm afraid that does happen occasionally, human nature being what it is.) patch attempts to swap each hunk around before applying it. Rejects come out in the swapped format. The -R option does not work with ed diff scripts because there is too little information to reconstruct the reverse operation. If the first hunk of a patch fails, patch reverses the hunk to see if it can be applied that way. If it can, you are asked if you want to have the -R option set. If it can't, the patch continues to be applied normally. (Note: this method cannot detect a reversed patch if it is a normal diff and if the first command is an append (i.e. it should have been a delete) since appends always succeed, due to the fact that a null context matches anywhere. Luckily, most patches add or change lines rather than delete them, so most reversed normal diffs begin with a delete, which fails, triggering the heuristic.) --read-only=behavior Behave as requested when trying to modify a read-only file: ignore the potential problem, warn about it (the default), or fail. --reject-format=format Produce reject files in the specified format (either context or unified). Without this option, rejected hunks come out in unified diff format if the input patch was of that format, otherwise in ordinary context diff form. -s or --silent or --quiet Work silently, unless an error occurs. --follow-symlinks When looking for input files, follow symbolic links. Replaces the symbolic links, instead of modifying the files the symbolic links point to. Git-style patches to symbolic links will no longer apply. This option exists for backwards compatibility with previous versions of patch; its use is discouraged. -t or --batch Suppress questions like -f, but make some different assumptions: skip patches whose headers do not contain file names (the same as -f); skip patches for which the file has the wrong version for the Prereq: line in the patch; and assume that patches are reversed if they look like they are. -T or --set-time Set the modification and access times of patched files from time stamps given in context diff headers. Unless specified in the time stamps, assume that the context diff headers use local time. Use of this option with time stamps that do not include time zones is not recommended, because patches using local time cannot easily be used by people in other time zones, and because local time stamps are ambiguous when local clocks move backwards during daylight- saving time adjustments. Make sure that time stamps include time zones, or generate patches with UTC and use the -Z or --set-utc option instead. -u or --unified Interpret the patch file as a unified context diff. -v or --version Print out patch's revision header and patch level, and exit. -V method or --version-control=method Use method to determine backup file names. The method can also be given by the PATCH_VERSION_CONTROL (or, if that's not set, the VERSION_CONTROL) environment variable, which is overridden by this option. The method does not affect whether backup files are made; it affects only the names of any backup files that are made. The value of method is like the GNU Emacs `version-control' variable; patch also recognizes synonyms that are more descriptive. The valid values for method are (unique abbreviations are accepted): existing or nil Make numbered backups of files that already have them, otherwise simple backups. This is the default. numbered or t Make numbered backups. The numbered backup file name for F is F.~N~ where N is the version number. simple or never Make simple backups. The -B or --prefix, -Y or --basename-prefix, and -z or --suffix options specify the simple backup file name. If none of these options are given, then a simple backup suffix is used; it is the value of the SIMPLE_BACKUP_SUFFIX environment variable if set, and is .orig otherwise. With numbered or simple backups, if the backup file name is too long, the backup suffix ~ is used instead; if even appending ~ would make the name too long, then ~ replaces the last character of the file name. --verbose Output extra information about the work being done. -x num or --debug=num Set internal debugging flags of interest only to patch patchers. -Y pref or --basename-prefix=pref Use the simple method to determine backup file names (see the -V method or --version-control method option), and prefix pref to the basename of a file name when generating its backup file name. For example, with -Y .del/ the simple backup file name for src/patch/util.c is src/patch/.del/util.c. -z suffix or --suffix=suffix Use the simple method to determine backup file names (see the -V method or --version-control method option), and use suffix as the suffix. For example, with -z - the backup file name for src/patch/util.c is src/patch/util.c-. -Z or --set-utc Set the modification and access times of patched files from time stamps given in context diff headers. Unless specified in the time stamps, assume that the context diff headers use Coordinated Universal Time (UTC, often known as GMT). Also see the -T or --set-time option. The -Z or --set-utc and -T or --set-time options normally refrain from setting a file's time if the file's original time does not match the time given in the patch header, or if its contents do not match the patch exactly. However, if the -f or --force option is given, the file time is set regardless. Due to the limitations of diff output format, these options cannot update the times of files whose contents have not changed. Also, if you use these options, you should remove (e.g. with make clean) all files that depend on the patched files, so that later invocations of make do not get confused by the patched files' times. ENVIRONMENT PATCH_GET This specifies whether patch gets missing or read-only files from RCS, ClearCase, Perforce, or SCCS by default; see the -g or --get option. POSIXLY_CORRECT If set, patch conforms more strictly to the POSIX standard by default: see the --posix option. QUOTING_STYLE Default value of the --quoting-style option. SIMPLE_BACKUP_SUFFIX Extension to use for simple backup file names instead of .orig. TMPDIR, TMP, TEMP Directory to put temporary files in; patch uses the first environment variable in this list that is set. If none are set, the default is system-dependent; it is normally /tmp on Unix hosts. VERSION_CONTROL or PATCH_VERSION_CONTROL Selects version control style; see the -v or --version-control option. FILES $TMPDIR/p* temporary files /dev/tty controlling terminal; used to get answers to questions asked of the user SEE ALSO diff(1), ed(1), merge(1). Marshall T. Rose and Einar A. Stefferud, Proposed Standard for Message Encapsulation, Internet RFC 934 (1985-01). NOTES FOR PATCH SENDERS There are several things you should bear in mind if you are going to be sending out patches. Create your patch systematically. A good method is the command diff -Naur old new where old and new identify the old and new directories. The names old and new should not contain any slashes. The diff command's headers should have dates and times in Universal Time using traditional Unix format, so that patch recipients can use the -Z or --set-utc option. Here is an example command, using Bourne shell syntax: LC_ALL=C TZ=UTC0 diff -Naur gcc-2.7 gcc-2.8 Tell your recipients how to apply the patch by telling them which directory to cd to, and which patch options to use. The option string -Np1 is recommended. Test your procedure by pretending to be a recipient and applying your patch to a copy of the original files. You can save people a lot of grief by keeping a patchlevel.h file which is patched to increment the patch level as the first diff in the patch file you send out. If you put a Prereq: line in with the patch, it won't let them apply patches out of order without some warning. You can create a file by sending out a diff that compares /dev/null or an empty file dated the Epoch (1970-01-01 00:00:00 UTC) to the file you want to create. This only works if the file you want to create doesn't exist already in the target directory. Conversely, you can remove a file by sending out a context diff that compares the file to be deleted with an empty file dated the Epoch. The file will be removed unless patch is conforming to POSIX and the -E or --remove-empty-files option is not given. An easy way to generate patches that create and remove files is to use GNU diff's -N or --new-file option. If the recipient is supposed to use the -pN option, do not send output that looks like this: diff -Naur v2.0.29/prog/README prog/README --- v2.0.29/prog/README Mon Mar 10 15:13:12 1997 +++ prog/README Mon Mar 17 14:58:22 1997 because the two file names have different numbers of slashes, and different versions of patch interpret the file names differently. To avoid confusion, send output that looks like this instead: diff -Naur v2.0.29/prog/README v2.0.30/prog/README --- v2.0.29/prog/README Mon Mar 10 15:13:12 1997 +++ v2.0.30/prog/README Mon Mar 17 14:58:22 1997 Avoid sending patches that compare backup file names like README.orig, since this might confuse patch into patching a backup file instead of the real file. Instead, send patches that compare the same base file names in different directories, e.g. old/README and new/README. Take care not to send out reversed patches, since it makes people wonder whether they already applied the patch. Try not to have your patch modify derived files (e.g. the file configure where there is a line configure: configure.in in your makefile), since the recipient should be able to regenerate the derived files anyway. If you must send diffs of derived files, generate the diffs using UTC, have the recipients apply the patch with the -Z or --set-utc option, and have them remove any unpatched files that depend on patched files (e.g. with make clean). While you may be able to get away with putting 582 diff listings into one file, it may be wiser to group related patches into separate files in case something goes haywire. DIAGNOSTICS Diagnostics generally indicate that patch couldn't parse your patch file. If the --verbose option is given, the message Hmm... indicates that there is unprocessed text in the patch file and that patch is attempting to intuit whether there is a patch in that text and, if so, what kind of patch it is. patch's exit status is 0 if all hunks are applied successfully, 1 if some hunks cannot be applied or there were merge conflicts, and 2 if there is more serious trouble. When applying a set of patches in a loop it behooves you to check this exit status so you don't apply a later patch to a partially patched file. CAVEATS Context diffs cannot reliably represent the creation or deletion of empty files, empty directories, or special files such as symbolic links. Nor can they represent changes to file metadata like ownership, permissions, or whether one file is a hard link to another. If changes like these are also required, separate instructions (e.g. a shell script) to accomplish them should accompany the patch. patch cannot tell if the line numbers are off in an ed script, and can detect bad line numbers in a normal diff only when it finds a change or deletion. A context diff using fuzz factor 3 may have the same problem. You should probably do a context diff in these cases to see if the changes made sense. Of course, compiling without errors is a pretty good indication that the patch worked, but not always. patch usually produces the correct results, even when it has to do a lot of guessing. However, the results are guaranteed to be correct only when the patch is applied to exactly the same version of the file that the patch was generated from. COMPATIBILITY ISSUES The POSIX standard specifies behavior that differs from patch's traditional behavior. You should be aware of these differences if you must interoperate with patch versions 2.1 and earlier, which do not conform to POSIX. o In traditional patch, the -p option's operand was optional, and a bare -p was equivalent to -p0. The -p option now requires an operand, and -p 0 is now equivalent to -p0. For maximum compatibility, use options like -p0 and -p1. Also, traditional patch simply counted slashes when stripping path prefixes; patch now counts pathname components. That is, a sequence of one or more adjacent slashes now counts as a single slash. For maximum portability, avoid sending patches containing // in file names. o In traditional patch, backups were enabled by default. This behavior is now enabled with the -b or --backup option. Conversely, in POSIX patch, backups are never made, even when there is a mismatch. In GNU patch, this behavior is enabled with the --no-backup-if-mismatch option, or by conforming to POSIX with the --posix option or by setting the POSIXLY_CORRECT environment variable. The -b suffix option of traditional patch is equivalent to the -b -z suffix options of GNU patch. o Traditional patch used a complicated (and incompletely documented) method to intuit the name of the file to be patched from the patch header. This method did not conform to POSIX, and had a few gotchas. Now patch uses a different, equally complicated (but better documented) method that is optionally POSIX-conforming; we hope it has fewer gotchas. The two methods are compatible if the file names in the context diff header and the Index: line are all identical after prefix-stripping. Your patch is normally compatible if each header's file names all contain the same number of slashes. o When traditional patch asked the user a question, it sent the question to standard error and looked for an answer from the first file in the following list that was a terminal: standard error, standard output, /dev/tty, and standard input. Now patch sends questions to standard output and gets answers from /dev/tty. Defaults for some answers have been changed so that patch never goes into an infinite loop when using default answers. o Traditional patch exited with a status value that counted the number of bad hunks, or with status 1 if there was real trouble. Now patch exits with status 1 if some hunks failed, or with 2 if there was real trouble. o Limit yourself to the following options when sending instructions meant to be executed by anyone running GNU patch, traditional patch, or a patch that conforms to POSIX. Spaces are significant in the following list, and operands are required. -c -d dir -D define -e -l -n -N -o outfile -pnum -R -r rejectfile BUGS Please report bugs via email to . If code has been duplicated (for instance with #ifdef OLDCODE ... #else ... #endif), patch is incapable of patching both versions, and, if it works at all, will likely patch the wrong one, and tell you that it succeeded to boot. If you apply a patch you've already applied, patch thinks it is a reversed patch, and offers to un-apply the patch. This could be construed as a feature. Computing how to merge a hunk is significantly harder than using the standard fuzzy algorithm. Bigger hunks, more context, a bigger offset from the original location, and a worse match all slow the algorithm down. COPYING Copyright (C) 1984, 1985, 1986, 1988 Larry Wall. Copyright (C) 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2009 Free Software Foundation, Inc. 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 included in translations approved by the copyright holders instead of in the original English. AUTHORS Larry Wall wrote the original version of patch. Paul Eggert removed patch's arbitrary limits; added support for binary files, setting file times, and deleting files; and made it conform better to POSIX. Other contributors include Wayne Davison, who added unidiff support, and David MacKenzie, who added configuration and backup support. Andreas Grunbacher added support for merging. GNU PATCH(1)