DIFF(1) COMMAND REFERENCE DIFF(1)
NAME
diff - differential file and directory comparator
SYNOPSIS
diff [-l] [-r] [-s] [-Sfilename] [-{c,e,f,h}] [-b] dir1 dir2
diff [-{c,e,f,h}] [-b] file1 file2
diff [-Dstring] [-b] file1 file2
DESCRIPTION
In the first form of the command line, diff sorts the
contents of the directories by name, and then runs the
regular file diff algorithm (described below) on text files
which are different. Binary files which differ, common
subdirectories, and files which appear in only one directory
are listed.
In the second and third forms, and when comparing text files
which differ during directory comparison, diff tells what
lines must be changed in the files to bring them into
agreement. Except in rare circumstances, diff finds a
smallest sufficient set of file differences. If neither
file1 nor file2 is a directory, then either may be given as
`-', in which case the standard input is used. If file1 is
a directory, then a file in that directory whose file-name
is the same as the file-name of file2 is used (and vice
versa).
There are several options for output format; the default
output format contains lines of these forms:
n1 a n3,n4
n1,n2 d n3
n1,n2 c n3,n4
These lines resemble ed commands to convert file1 into
file2. The numbers after the letters pertain to file2. In
fact, by exchanging `a' for `d' and reading backward one may
ascertain equally how to convert file2 into file1. As in
ed, identical pairs where n1 = n2 or n3 = n4 are abbreviated
as a single number.
Following each of these lines come all the lines that are
affected in the first file flagged by `<', then all the
lines that are affected in the second file flagged by `>'.
OPTIONS
Options when comparing directories are:
-l Long output format; each text file diff is piped through
pr(1) to paginate it, other differences are remembered
and summarized after all text file differences are
reported.
Printed 4/6/89 1
DIFF(1) COMMAND REFERENCE DIFF(1)
-r Causes application of diff recursively to common
subdirectories encountered.
-s Causes diff to report files which are the same, which are
otherwise not mentioned.
-Sfilename
Starts a directory diff in the middle beginning with
filename.
Except for -b, which may be given with any of the others,
the following options are mutually exclusive:
-b Causes trailing blanks (spaces and tabs) to be ignored,
and other strings of blanks to compare equal.
-c Produces a diff with lines of context. The default is to
present 3 lines of context and may be changed, e.g to 10,
by -c10. With -c the output format is modified slightly:
the output beginning with identification of the files
involved and their creation dates and then each change is
separated by a line with a dozen *'s. The lines removed
from file1 are marked with `-'; those added to file2 are
marked `+'. Lines which are changed from one file to the
other are marked in both files with `!'.
-e Produces a script of a, c and d commands for the editor
ed, which will recreate file2 from file1. In connection
with -e, the following shell program may help maintain
multiple versions of a file. Only an ancestral file ($1)
and a chain of version-to-version ed scripts ($2,$3,...)
made by diff need be on hand. A `latest version' appears
on the standard output.
(shift; cat $*; echo '1,$p') | ed - $1
Extra commands are added to the output when comparing
directories with -e, so that the result is a sh(1sh)
script for converting text files which are common to the
two directories from their state in dir1 to their state
in dir2.
-f Produces a script similar to that of -e, not useful with
ed, and in the opposite order.
-h Does a fast, half-hearted job. It works only when
changed stretches are short and well separated, but does
work on files of unlimited length. Only recognizes the
-b option. All other options are ignored.
-Dstring
Causes diff to create a merged version of file1 and file2
Printed 4/6/89 2
DIFF(1) COMMAND REFERENCE DIFF(1)
on the standard output, with C preprocessor controls
included so that a compilation of the result without
defining string is equivalent to compiling file1, while
defining string will yield file2.
EXAMPLES
The following invocation performs the difference function on
the files pgm.version1 and pgm.version2. The results are
written on standard output.
diff pgm.version1 pgm.version2
FILES
/tmp/d????? Temporary files
/usr/lib/diffh
half-hearted (-h) diff function
RETURN VALUE
[0] No differences.
[1] There are differences.
[USAGE] Incorrect command line syntax. Execution
terminated.
[NP_WARN] An error warranting a warning message
occurred. Execution continues.
[NP_ERR] An error occurred that was not a system
error. Execution terminated.
[P_WARN] A system error occurred. Execution continues.
See intro(2) for more information on system
errors.
[P_ERR] A system error occurred. Execution
terminated. See intro(2) for more
information on system errors.
[INTERNAL] An unexpected error occurred. Execution was
terminated. Record the message and save the
core file for analysis. Contact service
personnel at your Tektronix field office.
CAVEATS
Editing scripts produced under the -e or -f option are naive
about creating lines consisting of a single `.'.
When comparing directories with the -b option specified,
diff first compares the files ala cmp(1), and then decides
to run the diff algorithm if they are not equal. This may
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DIFF(1) COMMAND REFERENCE DIFF(1)
cause a small amount of spurious output if the files then
turn out to be identical because the only differences are
insignificant blank string differences.
SEE ALSO
cmp(1), cc(1), comm(1), ed(1), diff3(1), and pr(1).
Printed 4/6/89 4
%%index%%
na:240,101;
sy:341,798;
de:1139,2059;
op:3198,393;3903,2980;7195,273;
ex:7468,294;
fi:7762,212;
rv:7974,1117;
ca:9091,547;9950,172;
se:10122,230;
%%index%%000000000179