HP-UX Reference (11i v2 07/12) - 1 User Commands N-Z (vol 2)

p
patch(1) patch(1)
NAME
patch - program for applying a diff file to an original
SYNOPSIS
Non-XPG4 version
patch [options] orig patchfile [
+ [options] orig]
patch <patchfile # usual form
XPG4 version
patch [-blNR][-c
-e-n][-d dir][-D define][
-i patchfile][-o outfile][
-p num]
[
-r rejectfile][file]
DESCRIPTION
patch will take a patch file containing any of the three forms of difference listing produced by the
diff
program (normal, context or in the style of
ed) and apply those differences to an original file, producing a
patched version. By default, the patched version is put in place of the original, with the original file backed
up to the same name with the extension
.orig, or as specified by the -b option. Note that the functional-
ity of this option varies for the XPG4 version. You may also specify where you want the output to go with a
-o option. If patchfile is omitted, or is a hyphen (-), the patch will be read from standard input. For the
XPG4 version, patchfile has to be specified as the argument of the
-i option. If this option is omitted or a
hyphen is specified as argument, the patch will be read from standard input.
Upon startup, patch will attempt to determine the type of the diff listing, unless overruled by a
-c, -e,or
-n option. Context diffs and normal diffs are applied by the patch
program itself, while ed diffs are sim-
ply fed to the
ed editor via a pipe.
patch will try to skip any leading garbage, apply the diff, and then skip any trailing garbage. Thus you
could feed an article or message containing a diff listing to patch, and it should work. If the entire diff is
indented by a consistent amount, this will be taken into account.
With context diffs, and to a lesser extent with normal diffs, patch
can detect when the line numbers men-
tioned in the patch are incorrect, and will attempt to find the correct place to apply each hunk of the patch.
As a first guess, it takes the line number mentioned for the hunk, plus or minus any offset used in applying
the previous hunk. If that is not the correct place,
patch will scan both forward and backward for a set of
lines matching the context given in the hunk. First, patch looks for a place where all lines of the context
match. If no such place is found, and it’s a context diff, and the maximum fuzz factor is set to 1 or more,
then another scan takes place ignoring the first and last line of context. If that fails, and the maximum
fuzz factor is set to 2 or more, the first two and last two lines of context are ignored, and another scan is
made. (The default maximum fuzz factor is 2.) Note that, for the XPG4 version, the maximum fuzz factor
can not be specified as an option and the default maximum fuzz factor is used. If
patch cannot find a
place to install that hunk of the patch, it will put the hunk out to a reject file, which normally is the name
of the output file plus
.rej. (Note that the rejected hunk will come out in context diff form whether the
input patch was a context diff or a normal diff. If the input was a normal diff, many of the contexts will
simply be null.) The line numbers on the hunks in the reject file may be different than in the patch file:
they reflect the approximate location patch thinks the failed hunks belong in the new file rather than the
old one.
As each hunk is completed, you will be told whether the hunk succeeded or failed, and which line (in the
new file) patch thought the hunk should go on. If this is different from the line number specified in the
diff you will be told the offset. A single large offset may be an indication that a hunk was installed in the
wrong place. You will also be told if a fuzz factor was used to make the match, in which case you should
also be slightly suspicious. Note that the XPG4 version does not support the verbose option. So, most of
the diagnostic messages are not printed for this version. However user queries will always be displayed.
If no original file is specified on the command line, patch will try to figure out from the leading garbage
what the name of the file to edit is. In the header of a context diff, the file name is found from lines begin-
ning with *** or ---, with the shortest name of an existing file winning. Only context diffs have lines
like that, but if there is an Index: line in the leading garbage, patch will try to use the file name from
that line. The context diff header takes precedence over an Index line. If no file name can be intuited from
the leading garbage, you will be asked for the name of the file to patch.
(If the original file cannot be found, but a suitable SCCS or RCS file is handy, patch will attempt to get or
check out the file.)
134 Hewlett-Packard Company − 1 − HP-UX 11i Version 2: December 2007 Update