diff - find differences between two files

In the simplest case, diff compares the contents of the two files from-file and to-file. A file name of - stands for text read from the standard input. As a special case, diff - - compares a copy of standard input to itself.

If from-file is a directory and to-file is not, diff compares the file in from-file whose file name is that of to-file, and vice versa. The non-directory file must not be -.

If both from-file and to-file are directories, diff compares corresponding files in both directories, in alphabetical order; this comparison is not recursive unless the --recursive option is given. diff never compares the actual contents of a directory as if it were a file. The file that is fully specified may not be standard input, because standard input is nameless and the notion of ``file with the same name'' does not apply.

-B, --ignore-blank-lines

Ignore changes that just insert or delete blank lines.

-C, --context=lines

Use the context output format, showing lines lines of context. For proper operation, patch(1) typically needs at least 2 lines of context. The default value is 3.

-D, --ifdef=macro

Make merged if-then-else format output, conditional on the preprocessor macro macro.

-F, --show-function-line=pattern

In context and unified format, for each hunk of differences, show some of the last preceding line that matches the regular expression pattern.

-H, --speed-large-files

Use heuristics to speed handling of large files that have numerous scattered small changes.

-I, --ignore-matching-lines=pattern

Ignore changes that just insert or delete lines that match the regular expression pattern.

-L, --label|file-label=label

Use label instead of the file name in the context format and unified format headers.

-N, --new-file|entire-new-file

In directory comparison, if a file is found in only one directory, treat it as present but empty in the other directory.

-P, --unidirectional-new-file

When comparing directories, if a file appears only in the second directory of the two, treat it as present but empty in the other.

-S, --starting-file=file

When comparing directories, start with the file file. This is for resuming an interrupted comparison.

-T, --initial-tab

Output a tab rather than a space before the text of a line in normal or context format. This causes the alignment of tabs in the line to look normal.

-W, --width=columns

Use an output width of columns in side by side format.

-a, --text|ascii

Treat all files as text and compare them line-by-line, even if they do not seem to be text.

-b, --ignore-space-change

Ignore changes in amount of white space.

-d, --minimal

Change the algorithm to perhaps find a smaller set of changes. This makes diff slower (sometimes much slower).

-e, --ed

Make output that is a valid ed(1) script.

-f, --forward-ed

Make output that looks vaguely like an ed(1) script but has changes in the order they appear in the file.

-i, --ignore-case

Ignore changes in case; consider upper- and lower-case letters equivalent.

-l, --paginate|print

Pass the output through pr(1) to paginate it.

-n, --rcs

Output rcs(1) format diffs; like --forward-ed except that each command specifies the number of lines affected.

-p, --show-c-function

Show which C function each change is in.

-q, --brief

Report only whether the files differ, not the details of the differences.

-r, --recursive

When comparing directories, recursively compare any subdirectories found.

-s, --report-identical-files

Report when two files are the same.

-t, --expand-tabs

Expand tabs to spaces in the output, to preserve the alignment of tabs in the input files.

-w, --ignore-all-space

Ignore white space when comparing lines.

-x, --exclude=pattern

When comparing directories, ignore files and subdirectories whose basenames match the sh(1) file match pattern.

-X, --exclude-from=file

When comparing directories, ignore files and subdirectories whose basenames match any pattern contained in file, where each is taken to be one sh(1) file match pattern.

-y, --side-by-side

Use the side by side output format.

-U, --unified[=lines]

Use the unified output format, showing lines lines of context. For proper operation patch(1) typically needs at least 2 lines of context. The option value may be omitted. The default value is 3.

--left-column

Print only the left column of two common lines in side by side format.

--suppress-common-lines

Do not print common lines in side by side format.

--sdiff-merge-assist

Print extra information to help sdiff(1). Not intended for other use besides sdiff.

--old-line-format=format

Use format to output a line taken from just the first file in if-then-else format.

--new-line-format=format

Use format to output a line taken from just the second file in if-then-else format.

--unchanged-line-format=format

Use format to output a line common to both files in if-then-else format.

--line-format=format

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

--old-group-format=format

Use format to output a group of lines taken from just the first file in if-then-else format.

--new-group-format=format

Use format to output a group of lines taken from just the second file in if-then-else format.

--unchanged-group-format=format

Use format to output a group of common lines taken from both files in if-then-else format.

--changed-group-format=format

Use format to output a line group containing differing lines from both files in if-then-else format.

--horizon-lines=lines

Do not discard the last lines lines of the common prefix and the first lines lines of the common suffix.

--binary

Read and write data in binary mode. Ignored on some systems.

-c

Equivalent to --context=3.

-h

Ignored by this implementation.

-u

Equivalent to --unified=3.

-v

Print the program version and exit.

0

No differences were found.

1

Some differences were found.

2

An error occurred.

cmp(1), comm(1), diff3(1), ed(1), patch(1), pr(1), sdiff(1)

version

diff (GNU diffutils 2.7) 1994-10-01

author

Paul Eggert

author

Richard Stallman

author

Mike Haertel

author

David Hayes

author

Len Tower

copyright

Copyright © 1988-2012 GNU Free Software Foundation

license

http://www.gnu.org/copyleft/gpl.html