Man1 - diff.1

Table of Contents


diff - compare files line by line


diff [/OPTION/]… FILES


Compare FILES line by line.

Mandatory arguments to long options are mandatory for short options too.

output a normal diff (the default)
-q, –brief
report only when files differ
-s, –report-identical-files
report when two files are the same
-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
-e, –ed
output an ed script
-n, –rcs
output an RCS format diff
-y, –side-by-side
output in two columns
-W, *–width*=/NUM/
output at most NUM (default 130) print columns
output only the left column of common lines
do not output common lines
-p, –show-c-function
show which C function each change is in
-F, *–show-function-line*=/RE/
show the most recent line matching RE
–label LABEL
use LABEL instead of file name and timestamp (can be repeated)
-t, –expand-tabs
expand tabs to spaces in output
-T, –initial-tab
make tabs line up by prepending a tab
tab stops every NUM (default 8) print columns
suppress space or tab before empty output lines
-l, –paginate
pass output through ’pr’ to paginate it
-r, –recursive
recursively compare any subdirectories found
don’t follow symbolic links
-N, –new-file
treat absent files as empty
treat absent first files as empty
ignore case when comparing file names
consider case when comparing file names
-x, *–exclude*=/PAT/
exclude files that match PAT
-X, *–exclude-from*=/FILE/
exclude files that match any pattern in FILE
-S, *–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
-i, –ignore-case
ignore case differences in file contents
-E, –ignore-tab-expansion
ignore changes due to tab expansion
-Z, –ignore-trailing-space
ignore white space at line end
-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 where lines are all blank
-I, *–ignore-matching-lines*=/RE/
ignore changes where all lines match RE
-a, –text
treat all files as text
strip trailing carriage return on input
-D, *–ifdef*=/NAME/
output merged file with ’#ifdef NAME’ diffs
format GTYPE input groups with GFMT
format all input lines with LFMT

format LTYPE input lines with LFMT

These format options provide fine-grained control over the output

of diff, generalizing *-D*/–ifdef.

LTYPE is ’old’, ’new’, or ’unchanged’.

GTYPE is LTYPE or ’changed’.

GFMT (only) 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

if A equals B then T else E

LFMT (only) may contain:

contents of line
contents of line, excluding any trailing newline

printf-style spec for input line number

Both GFMT and LFMT may contain:

the single character C
the character with octal code OOO
the character C (other characters represent themselves)
-d, –minimal
try hard to find a smaller set of changes
keep NUM lines of the common prefix and suffix
assume large files and many scattered small changes
color output; WHEN is ’never’, ’always’, or ’auto’; plain –color means –color=’auto’
the colors to use when –color is active; PALETTE is a colon-separated list of terminfo capabilities
display this help and exit
-v, –version
output version information and exit

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 FILE(s). If a FILE is ’-’, read standard input. Exit status is 0 if inputs are the same, 1 if different, 2 if trouble.


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


Report bugs to:
GNU diffutils home page:
General help using GNU software:


Copyright © 2021 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.


wdiff(1), cmp(1), diff3(1), sdiff(1), patch(1)

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.

Author: dt

Created: 2022-02-22 Tue 17:36