diff(1) (Essential Utilities) diff(1)
NAME
diff - differential file comparator
SYNOPSIS
diff [ -bitw ] [ -c|-e|-f |-h|-n ] filename1 filename2
diff [ -bitw ] [ -C number ] filename1 filename2
diff [ -bitw ] [ -D string ] filename1 filename2
diff [ -bitw ] [ -c|-e| -f|-h|-n ] [-l] [-r] [-s] [ -S name ]
directory1 directory2
DESCRIPTION
diff tells what lines must be changed in two files to bring them into
agreement. If filename1 (filename2) is -, the standard input is
used. If filename1 (filename2) is a directory, then a file in that
directory with the name filename2 (filename1) is used. The normal
output 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 filename1 into filename2.
The numbers after the letters pertain to filename2. In fact, by
exchanging a for d and reading backward one may ascertain equally how
to convert filename2 into filename1. 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 >.
-b Ignores trailing blanks (spaces and tabs) and treats other
strings of blanks as equivalent.
-i Ignores the case of letters; for example, `A' will compare
equal to `a'.
-t Expands TAB characters in output lines. Normal or -c output
adds character(s) to the front of each line that may adversely
affect the indentation of the original source lines and make
the output lines difficult to interpret. This option will
preserve the original source's indentation.
-w Ignores all blanks (SPACE and TAB characters) and treats all
other strings of blanks as equivalent; for example,
`if ( a == b )' will compare equal to `if(a==b)'.
The following options are mutually exclusive:
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diff(1) (Essential Utilities) diff(1)
-c Produces a listing of differences with three lines of context.
With this option output format is modified slightly: output
begins with identification of the files involved and their
creation dates, then each change is separated by a line with a
dozen *'s. The lines removed from filename1 are marked with
'-'; those added to filename2 are marked '+'. Lines that are
changed from one file to the other are marked in both files
with '!'.
-C number
Produces a listing of differences identical to that produced by
-c with number lines of context.
-e Produces a script of a, c, and d commands for the editor ed,
which will recreate filename2 from filename1. 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
Except in rare circumstances, diff finds a smallest sufficient set of
file differences.
-f Produces a similar script, not useful with ed, 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. Options -e and -f are unavailable with
-h.
-n Produces a script similar to -e, but in the opposite order and
with a count of changed lines on each insert or delete command.
-D string
Creates a merged version of filename1 and filename2 with C
preprocessor controls included so that a compilation of the
result without defining string is equivalent to compiling
filename1, while defining string will yield filename2.
The following options are used for comparing directories:
-l Produce output in long format. Before the diff, each text file
is piped through pr(1) to paginate it. Other differences are
remembered and summarized after all text file differences are
reported.
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diff(1) (Essential Utilities) diff(1)
-r Applies diff recursively to common subdirectories encountered.
-s Reports files that are the identical; these would not otherwise
be mentioned.
-S name
Starts a directory diff in the middle, beginning with the file
name.
FILES
/tmp/d?????
/usr/lib/diffh for -h
/usr/bin/pr
SEE ALSO
bdiff(1), cmp(1), comm(1), ed(1), pr(1).
DIAGNOSTICS
Exit status is 0 for no differences, 1 for some differences, 2 for
trouble.
NOTES
Editing scripts produced under the -e or -f option are naive about
creating lines consisting of a single period (.).
Missing newline at end of file X
indicates that the last line of file X did not have a new-line. If
the lines are different, they will be flagged and output; although
the output will seem to indicate they are the same.
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