Linux Blog


Section: User Commands (1)
Updated: April 2002
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diff - compare files line by line  


diff [OPTION]... FILES  


Compare files line by line.
-i --ignore-case
Ignore case differences in file contents.
Ignore case when comparing file names.
Consider case when comparing file names.
-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 RE.
Strip trailing carriage return on input.
-a --text
Treat all files as text.
-c -C NUM --context[=NUM]
Output NUM (default 3) lines of copied context.
-u -U NUM --unified[=NUM]
Output NUM (default 3) lines of unified context.
--label LABEL
Use LABEL instead of file name.
-p --show-c-function
Show which C function each change is in.
-F RE --show-function-line=RE
Show the most recent line matching RE.
-q --brief
Output only whether files differ.
-e --ed
Output an ed script.
Output a normal diff.
-n --rcs
Output an RCS format diff.
-y --side-by-side
Output in two columns.
-W NUM --width=NUM
Output at most NUM (default 130) print columns.
Output only the left column of common lines.
Do not output common lines.
-D NAME --ifdef=NAME
Output merged file to show `#ifdef NAME' diffs.
Similar, but format GTYPE input groups with GFMT.
Similar, but format all input lines with LFMT.
Similar, but format LTYPE input lines with LFMT.
LTYPE is `old', `new', or `unchanged'.
GTYPE is LTYPE or `changed'.
GFMT may contain:
lines from FILE1
lines from FILE2
lines common to FILE1 and FILE2
printf-style spec for LETTER
LETTERs are as follows for new group, lower case for old group:
first line number
last line number
number of lines = L-F+1
LFMT may contain:
contents of line
contents of line, excluding any trailing newline
printf-style spec for input line number
Either GFMT or LFMT may contain:
the single character C
the character with octal code OOO
-l --paginate
Pass the output through `pr' to paginate it.
-t --expand-tabs
Expand tabs to spaces in 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 empty.
Treat absent first files as empty.
-s --report-identical-files
Report when two files are the same.
-x PAT --exclude=PAT
Exclude files that match PAT.
-X FILE --exclude-from=FILE
Exclude files that match any pattern in FILE.
-S FILE --starting-file=FILE
Start with FILE when comparing directories.
Compare FILE1 to all operands. FILE1 can be a directory.
Compare all operands to FILE2. FILE2 can be a directory.
Keep NUM lines of the common prefix and suffix.
-d --minimal
Try hard to find a smaller set of changes.
Assume large files and many scattered small changes.
-v --version
Output version info.
Output this help.

FILES are `FILE1 FILE2' or `DIR1 DIR2' or `DIR FILE...' or `FILE... DIR'. If --from-file or --to-file is given, there are no restrictions on FILES. If a FILE is `-', read standard input.  


Written by Paul Eggert, Mike Haertel, David Hayes, Richard Stallman, and Len Tower.  


Report bugs to <>.  


Copyright © 2002 Free Software Foundation, Inc.

This program comes with NO WARRANTY, to the extent permitted by law. You may redistribute copies of this program under the terms of the GNU General Public License. For more information about these matters, see the file named COPYING.  


The full documentation for diff is maintained as a Texinfo manual. If the info and diff programs are properly installed at your site, the command
info diff

should give you access to the complete manual.




Linux Blog


examples of using diff

Remove lines that are in another file