diff3 - Man Page

• Compare files: diff3 path/to/file1 path/to/file2 path/to/file3
• Show all changes, outlining conflicts: diff3 [-A|--show-all] path/to/file1 path/to/file2 path/to/file3

tldr.sh

diff3 [OPTION]... MYFILE OLDFILE YOURFILE

Compare three files line by line.

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

-A,  --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

-X

like -x, but bracket conflicts

-i

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-cr

strip trailing carriage return on input

-T,  --initial-tab

make tabs line up by prepending a tab

--diff-program=PROGRAM

use PROGRAM to compare files

-L,  --label=LABEL

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

--help

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@gnu.org
GNU diffutils home page: <https://www.gnu.org/software/diffutils/>
General help using GNU software: <https://www.gnu.org/gethelp/>

Copyright © 2025 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
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.