diff ( 1 ) USER COMMANDSdiff ( 1 )

NAME

diff - find differences between two files

SYNOPSIS

diff [ options ] from-file to-file

DESCRIPTION

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.

OPTIONS

-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.

EXIT STATUS

0
No differences were found.
1
Some differences were found.
2
An error occurred.

SEE ALSO

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

IMPLEMENTATION

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 © 1988-2008 AT&T Intellectual Property
license
http://www.opensource.org/licenses/gpl1.0.txt