DIFF3(1)

NAME
diff3 - compare three files line by line

SYNOPSIS
diff3 [OPTION]... MYFILE OLDFILE YOURFILE

DESCRIPTION
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.

AUTHOR
Written by Randy Smith.

REPORTING BUGS
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
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.

SEE ALSO
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.