Linux Commands Examples

A great documentation place for Linux commands


compare three files line by line

see also : cmp - diff - sdiff



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echo usage: diff3 file1 file2 file3 1>&2
trap "rm -f /tmp/d3[ab]$$" 0 1 2 13 15
diff $1 $3 >/tmp/d3a$$
diff $1 $3 >/tmp/d3a$$
diff $2 $3 >/tmp/d3b$$
/usr/lib/diff3 $e /tmp/d3[ab]$$ $1 $2 $3


Compare three files line by line.

Mandatory arguments to long options are mandatory for short options too.
, --show-all

output all changes, bracketing conflicts

-e, --ed

output ed script incorporating changes from OLDFILE to YOURFILE into MYFILE

-E, --show-overlap

like -e, but bracket conflicts

-3, --easy-only

like -e, but incorporate only nonoverlapping changes

-x, --overlap-only

like -e, but incorporate only overlapping changes


like -x, but bracket conflicts


append ’w’ and ’q’ commands to ed scripts

-m, --merge

output actual merged file, according to -A if no other options are given

-a, --text

treat all files as text


strip trailing carriage return on input

-T, --initial-tab

make tabs line up by prepending a tab


use PROGRAM to compare files

-L, --label=LABEL

use LABEL instead of file name (can be repeated up to three times)


display this help and exit

-v, --version

output version information and exit

The default output format is a somewhat human-readable representation of the changes.

The -e, -E, -x, -X (and corresponding long) options cause an ed script to be output instead of the default.

Finally, the -m (--merge) option causes diff3 to do the merge internally and output the actual merged file. For unusual input, this is more robust than using ed.

If a FILE is ’-’, read standard input. Exit status is 0 if successful, 1 if conflicts, 2 if trouble.


Copyright © 2011 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.

reporting bugs

Report bugs to: bug-diffutils[:at:]gnu[:dot:]org
GNU diffutils home page: <>
General help using GNU software: <>

see also

cmp , diff , sdiff

The full documentation for diff3 is maintained as a Texinfo manual. If the info and diff3 programs are properly installed at your site, the command

info diff3

should give you access to the complete manual.


Written by Randy Smith.

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