DIFF(1) User Commands DIFF(1)

NAME

diff - compare two files

SYNOPSIS

diff [-biqtw] [-c | -e | -f | -h | -n | -u] file1 file2
diff [-biqtw] [-C number | -U number] file1 file2
diff [-biqtw] [-D string] file1 file2
diff [-biqtw] [-c | -e | -f | -h | -n | -u] [-l] [-r] [-s] [-S name]
directory1 directory2

DESCRIPTION

The diff utility will compare the contents of file1 and file2 and write to
standard output a list of changes necessary to convert file1 into file2.
This list should be minimal. Except in rare circumstances, diff finds a
smallest sufficient set of file differences. No output will be produced if
the files are identical.

The normal output contains lines of these forms:

n1an3,n4
n1,n2dn3
n1,n2cn3,n4

where n1 and n2 represent lines in file1 and n3 and n4 represent lines in
file2 These lines resemble ed(1) commands to convert file1 to file2. By
exchanging a for d and reading backwards, file2 can be converted to file1.
As in ed(1), 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

The following options are supported:

-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'.

-q report only when files differ

-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:

-c Produces a listing of differences with three lines of context.
With this option, output format is modified slightly. That is,
output begins with identification of the files involved and their
creation dates, then each change is separated by a line with a
dozen asterisks (*). The lines removed from file1 are marked with
`--'. The lines added to file2 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.

-D string
Creates a merged version of file1 and file2 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.

-e Produces a script of only a, c, and d commands for the editor
ed(1), which will recreate file2 from file1. In connection with
the -e option, 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 $*; echo a'1,$p') | ed - $1

-f Produces a similar script, not useful with ed(1), 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 -c, -C, -D, -e, -f, and -n are
unavailable with -h. diff does not descend into directories with
this option.

-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.

-u Produces a listing of differences with three lines of context. The
output is similar to that of the -c option, except that the context
is "unified". Removed and changed lines in file1 are marked by a
`-' while lines added or changed in file2 are marked by a `+'.
Both versions of changed lines appear in the output, while added,
removed, and context lines appear only once. The identification of
file1 and file2 is different, with "---" and "+++" being printed
where "***" and "---" would appear with the -c option. Each change
is separated by a line of the form

@@ -n1,n2 +n3,n4 @@

-U number
Produces a listing of differences identical to that produced by -u
with number lines of context.

The following options are used for comparing directories:

-l Produces 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 identical files would not
otherwise be mentioned.

-S name
Starts a directory diff in the middle, beginning with the file
name.

OPERANDS

The following operands are supported:

file1
file2 A path name of a file or directory to be compared. If
either file1 or file2 is `-', the standard input will be
used in its place.

directory1
directory2 A path name of a directory to be compared.

If only one of file1 and file2 is a directory, diff will be applied to the
non-directory file and the file contained in the directory file with a
filename that is the same as the last component of the non-directory file.

USAGE

See largefile(7) for the description of the behavior of diff when
encountering files greater than or equal to 2 Gbyte (2^31 bytes).

FILES

/tmp/d?????
temporary file used for comparison

/usr/lib/diffh
executable file for -h option

EXIT STATUS

The following exit values are returned:

0 No differences were found.

1 Differences were found.

>1 An error occurred.

EXAMPLES

Example 1 Typical output of the diff command

In the following command, dir1 is a directory containing a directory named
x, dir2 is a directory containing a directory named x, dir1/x and dir2/x
both contain files named date.out, and dir2/x contains a file named y:

example% diff -r dir1 dir2
Common subdirectories: dir1/x and dir2/x
Only in dir2/x: y
diff -r dir1/x/date.out dir2/x/date.out
1c1
< Mon Jul 2 13:12:16 PDT 1990
---
> Tue Jun 19 21:41:39 PDT 1990

ENVIRONMENT VARIABLES

See environ(7) for descriptions of the following environment variables that
affect the execution of diff: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES, LC_TIME,
and NLSPATH.

TZ Determines the locale for affecting the timezone used for
calculating file timestamps written with the -C and -c options.

INTERFACE STABILITY

The command line interface of diff is Committed. The output of diff is
Committed.

SEE ALSO

bdiff(1), cmp(1), comm(1), dircmp(1), ed(1), pr(1), sdiff(1),
attributes(7), environ(7), largefile(7), standards(7)

NOTES

Editing scripts produced under the -e or -f options are na"ive about
creating lines consisting of a single dot `.'.

Missing NEWLINE at end of file indicates that the last line of the file in
question did not have a NEWLINE. If the lines are different, they will be
flagged and output, although the output will seem to indicate they are the
same.

OmniOS February 23, 2022 OmniOS