DIFF(1) GENIX Programmer's Manual DIFF(1)
NAME
diff - differential file and directory comparator
SYNOPSIS
diff [ -l ] [ -r ] [ -s ] [ -cefh ] [ -b ] dir1 dir2
diff [ -cefh ] [ -b ] file1 file2
diff [ -Dstring ] [ -b ] file1 file2
DESCRIPTION
If both arguments are directories, 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. 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.
-r causes application of diff recursively to common subdirectories
encountered.
-s causes diff to report files which are the same, which are oth-
erwise not mentioned.
-Sname
starts a directory diff in the middle beginning with file name.
When run on regular files, 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 differ-
ences. 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 for-
mat 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
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DIFF(1) GENIX Programmer's Manual DIFF(1)
affected in the second file flagged by `>'.
Except for -b, which may be given with any of the others, the fol-
lowing options are mutually exclusive:
-e producing 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 mul-
tiple 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(1) 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.
-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 `!'.
-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.
-Dstring causes diff to create a merged version of file1 and file2
on the standard output, with C preprocessor controls
included so that a compilation of the result without defin-
ing string is equivalent to compiling file1, while defining
string will yield file2.
-b causes trailing blanks (spaces and tabs) to be ignored, and
other strings of blanks to compare equal.
FILES
/tmp/d?????
/usr/lib/diffh for -h
/usr/bin/pr
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DIFF(1) GENIX Programmer's Manual DIFF(1)
SEE ALSO
cmp(1), cc(1), comm(1), ed(1), diff3(1)
DIAGNOSTICS
Exit status is 0 for no differences, 1 for some, 2 for trouble.
BUGS
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, and then decides to run the diff algo-
rithm if they are not equal. This may 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.
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