LSSU(1)

💖 LSSU(1) — bestie's guide to the lssu command 💖

okay so welcome to the lssu(1) page, General Commands Manual edition, and babes we are about to learn how to peek at NILFS2 segment usage like it's the most natural thing in the world 🌸

---

✨ NAME ✨

lssu — list usage state of NILFS2 segments. that's it, that's the whole job description, and she does it beautifully 💅

---

✨ SYNOPSIS ✨

lssu [options] [device|node]

---

✨ DESCRIPTION ✨

so lssu is this little utility that shows you the usage state of NILFS2 segments in a device. and what even is a segment? bestie, a segment is a contiguous lump of disk blocks and also the allocation unit of NILFS2 disk space. iconic little building block fr fr 🧱

the device can be a block device or a filesystem node (so like a file or a directory) on the filesystem. and if you just. don't pass a device at all? no worries, she goes and checks /proc/mounts to find a NILFS2 file system for you. she's thoughtful like that 🫶

⚠️ real talk though: this command will fail if the device has no active mounts of a NILFS2 file system. like, no cap, she cannot work with nothing.

---

✨ OPTIONS ✨

• -a, --all — do not hide clean segments. show them all, let them shine ✨
• -h, --help — display the help message and exit. classic.
• -i index, --index=index — skip index segments at the start of input. bye bye, first few 👋
• -l, --latest-usage — print the usage status of the moment. like, the moment moment 🕐
• -n lines, --lines=lines — list only lines input segments.
• -p period, --protection-period=period — specify the protection period. this one is used when printing usage status of the moment (so, together with the -l option) to test if each block in segments is protected and is not reclaimable. and optionally, that period parameter may be suffixed by one of these unit designators: ´s´, ´m´, ´h´, ´d´, ´w´, ´M´, or ´Y´ — for seconds, minutes, hours, days, weeks, months, or years, respectively. yes the uppercase M is months and lowercase m is minutes, do not mix them up i'm begging 🙈
• -V, --version — display version and exit.

---

✨ FIELD DESCRIPTION ✨

every single line of the lssu output is made up of these fields, and we are going through every one of them because nobody gets left behind:

• SEGNUM — segment number. 🔢
• DATE — creation date. 📅
• TIME — creation time. ⏰
• STAT — state of the segment. and this one is made up of the following flags:
  • a — the segment is active, meaning that it is recently created and cannot be reclaimed by the garbage collector. she's new here, give her a sec 👑
  • d — the segment is dirty, meaning that it is in use.
  • e — the segment is erroneous, meaning that it has once caused an I/O error. NILFS2 avoids allocating the segments with this flag. 💀
  • p (optional) — the segment is protected, meaning that garbage collection for the segment is prevented for some reason. for instance: the protection period is not elapsed from its last modified time, the segment is pinned by the file system, or it is erroneous and unreclaimable, etc. this flag is displayed when the -l option is specified. 🛡️
• NBLOCKS — number of in-use blocks of the segment.
• NLIVEBLOCKS (optional) — number and ratio of in-use blocks of the moment. this field is displayed when the -l option is specified. 🦋

---

✨ AUTHOR ✨

Koji Sato — thank you for your service, legend 🌈

---

✨ AVAILABILITY ✨

lssu is part of the nilfs-utils package and is available from https://nilfs.sourceforge.io. go get her 💜

---

✨ SEE ALSO ✨

nilfs(8), dumpseg(8).

---

and that's the whole page bestie, you ate that 🎀 stay hydrated, mount responsibly, and remember: she's nilfs-utils version 2.3, dated Jan 2026 — periodt. 💅✨