OVERLAY(1)

🦋 OVERLAY — the overlay(1) manual, bestie edition

okay so picture this: you're deep in OverlayFS land, everything is layered, and you just need somebody to hold your hand and tell you which files actually changed. that's this. it's the overlay(1) page, and yes it's literally just called overlay. we're doing this together, grab a snack 🍓

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✨ NAME ✨

overlay — the manual page for overlay 77bf3f7. that's the whole name section, she's lowkey humble about it 💅

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🌸 SYNOPSIS 🌸

overlay command options

yeah. a command and then some options. that's the whole vibe. iconic structure, no notes 👑

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🎀 DESCRIPTION 🎀

💖 Commands:

so there are four commands and each one is a different flavor of "let me handle your overlay for you". pick your fighter:

• vacuum — removes duplicated files in upperdir where a copy_up has been done but the file isn't actually modified. like, girl, you didn't even change, why are you taking up space 😭 cleaning up the posers.
• diff — shows the list of the files that are actually, genuinely changed. no fakes, no phonies, just the real ones ✨
• merge — merges all the changes from upperdir into lowerdir, and then clears out upperdir. everything comes together, main character energy, the layers become one 🫶
• deref — copies changes from upperdir into a new upperdir, unfolding redirect and metacopy. yes, unfolding. like a little origami situation but for filesystem metadata 🧚

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🔥 OPTIONS 🔥

every single one, no skipping, we respect the full list in this house:

• -l, --lowerdir=LOWERDIR — the lowerdir of OverlayFS. this one is required, so don't come to the function without it 💀
• -u, --upperdir=UPPERDIR — the upperdir of OverlayFS. also required. the two required besties that must arrive together 🫂
• -m, --mountdir=MOUNTDIR — the mountdir of OverlayFS. this one's optional, she can come if she wants to 🌸
• -L, --lowernew=LOWERNEW — the lowerdir of the new OverlayFS. optional. the sequel lowerdir 💜
• -U, --uppernew=UPPERNEW — the upperdir of the new OverlayFS. optional. the sequel upperdir ⭐
• -v, --verbose — with the diff action only: when a directory exists in just one version, still list every file of that directory. so it's giving thorough. it's giving receipts. it's giving "no I want the WHOLE list" 📋
• -b, --brief — with the diff action only: conform to the output of diff --brief --recursive --no-dereference. so it goes short and snappy instead of chatty 🎀
• -h, --help — shows this help text. the classic. the comfort option. we love her 💖

okay bestie, real talk for a sec: see https://github.com/kmxz/overlayfs-tools/ for warnings and more information. warnings!! plural!! go read them, I'm not joking, don't just rawdog an overlay tool without checking the warnings 🙈

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and that's the whole page 🦋 you ate this. go forth and diff responsibly, no cap.

— cute little sign-off, as promised: this is overlay 77bf3f7, dated July 2025, and that's a wrap, periodt 💅✨