diff(1) 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. (It does not use the locale's collation
in the comparison.) If filename1 (filename2) is -, the
standard input is used. The LC_CTYPE environment variable
defines the codesets used in the filenames. 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:
n1an3,n4
n1,n2dn3
n1,n2cn3,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. The LC_CTYPE
environment variable determines what characters are
treated as blanks. [see ctype(3C) and LANG on
environ(5)].
-i Ignores the case of letters; for example, `A' will
compare equal to `a'. This option is also influenced by
the locale value in the LC_CTYPE environment variable.
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diff(1) diff(1)
-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. The LC_CTYPE environment variable
is used in correctly formatting the data, and so must
specify a locale that defines the same codesets as used
in the input data.
-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:
-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 dates are in
the format that output from date "+%a %b %e %T %Y"
produces. This is affected by the LC_TIME environment
variable. [see date(1) and LANG on environ(5)]. 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. The form
of number is affected by the LC_NUMERIC environment
variable. [see strtol(3C) and LANG on environ(5)].
-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
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diff(1) diff(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.
-r Applies diff recursively to common subdirectories
encountered.
-s Reports files that are 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
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/usr/lib/locale/locale/LC_MESSAGES/uxcore.abi
language-specific message file [see LANG on
environ(5)].
Errors
The exit status returns 0 if no differences are found, 1 if
differences are found, and 2 if an error occurred.
UX:diff: WARNING: 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.
REFERENCES
bdiff(1), cmp(1), comm(1), ed(1), pr(1)
NOTICES
Editing scripts produced under the -e or -f option are naive
about creating lines consisting of a single period (.).
diff will print a warning and ignore named pipes.
Copyright 1994 Novell, Inc. Page 4