COMM(1)

💖 COMM(1) 💖

okay bestie, so this is comm — it lives in the User Commands section of your manual, and it's literally the group-chat moderator for two sorted files. 🎀

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✨ NAME ✨

comm — compare two sorted files line by line 🦋

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🌸 SYNOPSIS 🌸

comm [OPTION]... FILE1 FILE2

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💅 DESCRIPTION 💅

So here's the vibe: you give it FILE1 and FILE2, both sorted, and it compares them line by line. That's it, that's the whole personality. 💜

And when FILE1 or FILE2 is -? It reads standard input instead. Slay. 🫶

With no options at all, you get three-column output:

• Column one — lines unique to FILE1 👑
• Column two — lines unique to FILE2 ✨
• Column three — lines common to both files 💖

Now the options, bestie, listen up:

• -1 — suppress column 1 (lines unique to FILE1) 🙈
• -2 — suppress column 2 (lines unique to FILE2) 💀
• -3 — suppress column 3 (lines that appear in both files) 😭
• --check-order — check that the input is correctly sorted, even if all input lines are pairable
• --nocheck-order — do not check that the input is correctly sorted
• --output-delimiter=STR — separate columns with STR 🌈
• --total — output a summary 🧚
• -z, --zero-terminated — line delimiter is NUL, not newline ⭐
• --help — display this help and exit
• --version — output version information and exit

and one more thing, no cap: comparisons honor the rules specified by 'LC_COLLATE'. 🎀

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🌈 EXAMPLES 🌈

comm -12 file1 file2  Print only lines present in both file1 and file2.
comm -3 file1 file2  Print lines in file1 not in file2, and vice versa.

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👑 AUTHOR 👑

Written by Richard M. Stallman and David MacKenzie. iconic behavior honestly 🫶

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🐛 REPORTING BUGS 🐛

Report bugs to: <bug-coreutils@gnu.org>. Report any translation bugs to: <https://translationproject.org/team/>. GNU coreutils home page: <https://www.gnu.org/software/coreutils/> General help using GNU software: <https://www.gnu.org/gethelp/>

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📜 COPYRIGHT 📜

Copyright © 2026 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.

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🦋 SEE ALSO 🦋

join(1), uniq(1)

Full documentation <https://www.gnu.org/software/coreutils/comm> or available locally via: info '(coreutils) comm invocation'

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okay that's the whole page, you ate that 💅 this was GNU coreutils 9.12, dated September 2026, and yes the footer says COMM(1) again because it loves being the main character 💖✨