`diff`

Compare two files, line by line (GNU)

Syntax:

diff [option] file1 file2

Options:

-i --ignore-case

Ignore case differences in the contents of the files.

--ignore-file-name-case

Ignore case when comparing filenames.

--no-ignore-file-name-case

Consider case when comparing filenames.

-E --ignore-tab-expansion

Ignore changes due to tab expansion.

-b --ignore-space-change

Ignore changes in the amount of white space.

-w --ignore-all-space

Ignore all white space.

-B --ignore-blank-lines

Ignore changes whose lines are all blank.

-I RE --ignore-matching-lines=RE

Ignore changes whose lines all match the given regular expression.

--strip-trailing-cr

Strip trailing carriage returns from the input.

-a --text

Treat all files as text.

-c -C num --context[=num]

Output num (default 3) lines of copied context.

-u -U num or --unified[=num]

Output num (default 3) lines of unified context.

--label label

Use label instead of the filename in the output. You can specify this option twice; the first applies to file1, and the second to file2.

-p --show-c-function

Show which C function each change is in.

-F RE --show-function-line=RE

Show the most recent line that matches the given regular expression.

-q --brief

Output only whether or not the files differ.

-e --ed

Output an ed script.

--normal

Display the differences in the normal format.

-n --rcs

Display the differences in RCS format.

-y --side-by-side

Display the output in two columns.

-W num --width=num

Output at most num (default 130) print columns.

--left-column

Output only the left column of common lines.

--suppress-common-lines

Don't display any lines that are common to both files.

-D name --ifdef=name

Output merged file to show #ifdef name differences.

--GTYPE-group-format=GFMT

Use the given format to output groups of lines in an if-then-else format. GTYPE can be old, new, changed, or unchanged.

GFMT may contain:

%<

Lines from file1.

%>

Lines from file2.

%=

Lines common to file1 and file2.

%[-][width][.[prec]]{doxX}letter

Use the given printf-style specification for the given letter. The letters are as follows for the new group; use lowercase letters for the old group:

F — the first line number
L — the last line number
N — the number of lines = L-F+1
E — F-1
M — L+1.

%%

A literal %.

%c'C'

The single character, C.

%c'\OOO'

The character with the given octal code, OOO.

--line-format=LFMT

Use the given format to output all input lines in an if-then-else format.

--LTYPE-line-format=LFMT

Use the given format to output individual lines in an if-then-else format. LTYPE can be old, new, or unchanged. LFMT may contain:

%L: Contents of the line.
%l: Contents of the line, excluding any trailing newline.
%[-][width][.[prec]]{doxX}n: Use the given printf-style specification for input line numbers.
%%: A literal %.
%c'C': The single character, C.
%c'\OOO': The character with the given octal code, OOO.

-l --paginate

Pass the output through pr to paginate it.

-t --expand-tabs

Expand tabs into spaces in the output.

-T --initial-tab

Make tabs line up by prepending a tab.

-r --recursive

Recursively compare any subdirectories found.

-N --new-file

Treat absent files as being empty.

--unidirectional-new-file

Treat absent first files as being empty.

-s --report-identical-files

Report when two files are the same.

-x pattern --exclude=pattern

Exclude files that match the given pattern.

-X file --exclude-from=file

Exclude files that match any pattern in file.

-S file --starting-file=file

Start with file when comparing directories.

--from-file=file1

Compare file1 to all operands. The file1 argument can also be the name of a directory.

--to-file=file2

Compare all operands to file2. The file2 argument can also be the name of a directory.

--horizon-lines=num

Keep num lines of the common prefix and suffix.

-d --minimal

Try hard to find a smaller set of changes.

--speed-large-files

Assume large files and many scattered small changes.

-v --version

Output version information.

--help

Display a help message.

file1, file2

Pathnames of the files to be compared. These can be in the following forms:

file1 file2
directory1 directory2
directory file...
file... directory

If you specify the --from-file or --to-file option, there are no restrictions on the files. If you specify a dash (-) instead of a filename, diff reads from standard input.

Description:

The diff utility reports the differences between two files.

If you use diff to compare binary files, diff simply reports whether or not the files are different. If you want to see the differences between two binary files, use cmp.

For any two files, there may be several correct interpretations of the differences between them. The diff utility attempts to generate the smallest number of additions, changes, and deletions required to convert file1 into file2. No output is produced if the files are identical.

This utility is subject to the GNU Public License (GPL). We've included it for use on development systems.

For detailed documentation about diff, see the GNU website at http://www.gnu.org/.

Exit status:

0: No differences were found.
1: Differences were found.
>1: An error occurred.

Contributing author:

GNU