diff3 − compare three files line by line




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.


Written by Randy Smith.


Report bugs to: bug−diffutils [AT]
GNU diffutils home page: <>;
General help using GNU software: <>;


Copyright © 2017 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.


cmp(1), diff(1), sdiff(1)

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.