Files and folders

Create, show, copy, move, search, delete: the most important commands for files.

All examples were typed on 29 Oct 2026 in NULLos 0.2 in QEMU.

Important: what stays after a restart

When NULLos starts, it loads a small file system into memory. Almost everything lives there: /bin, /etc, /tmp and also your home folder /. Whatever you create there is gone after a restart.

Only what is in /boot stays. That is the boot partition. In QEMU it lives in your image nullos.img (see QEMU and SSH). In NULLos itself, /boot is currently mounted read-only (as of 30 Oct 2026): you create new files for it on the Mac.

df shows the file system in memory:

Dateisystem              Typ         Größe     belegt       frei Anteil  eingehängt in
initrd                   ramfs       457 MiB    3.3 MiB    454 MiB     1%  /

The folders

l /

bin/   boot/  dev/   etc/   sys/   tmp/

Folder	Contents
`/bin`	all programs
`/boot`	the boot partition (stays after a restart)
`/dev`	devices
`/etc`	settings
`/sys`	help texts and descriptions of the commands
`/tmp`	room for temporary files

A short tour

cd /tmp
md probe/unter
pr "Hallo Welt" > probe/a.txt
sh probe/a.txt

Hallo Welt

cd changes the folder.
md creates a folder, and any missing parent folders along with it.
pr prints text, > writes it into a file.
sh shows a file (like cat).

Copy, move, rename

c probe/a.txt probe/b.txt
m probe/b.txt probe/unter/
rn probe/a.txt neu.txt

c copies. Whole folders with c -r.
m moves.
rn only changes the name; the file stays in the same folder.

c never overwrites without asking. If the target already exists, you get:

c: probe/b.txt: Existiert schon (mit -f überschreiben)

With c -f you overwrite on purpose.

Looking at things

l -l probe

-         11 2026-10-29 16:55 neu.txt
d          0 2026-10-29 16:56 unter/

Command	What it shows
`l`	contents of a folder; folders end with `/`
`l -l`	plus type, size and date
`l -t`	as a tree
`st DATEI`	type, size, permissions and times of a file
`sz ORDNER`	how much space folders and files take up (in bytes)
`sh DATEI`	the contents of a file
`hd -n 10 DATEI`	only the first 10 lines

Searching

g Welt probe/neu.txt
g -r Welt probe

probe/neu.txt:Hallo Welt
probe/unter/b.txt:Hallo Welt

g searches for text in files. With -r it searches all files in a folder.

f '*.txt' probe

f finds files by name. The pattern may contain * and ?. Put it in quotes so that the shell does not expand it first. h f shows more options, for example -t f (files only) or -s +1M (at least 1 MB).

Deleting

d probe/neu.txt
d -r probe

d deletes immediately and for good. There is no trash. d only deletes folders with -r:

d: probe ist ein Ordner (mit -r löschen)

Not sure? d -n -r probe only shows what would be deleted.

Editing

e notiz.txt

e is the editor. How it works is described in the project documentation under The editor.

USB stick

Since 30 Oct 2026 NULLos recognizes USB sticks. This was checked in QEMU with a stick image (FAT16), not yet with a real stick.

dv shows all devices. The stick appears as a disk, here sdb with the partition sdb1:

disk  sdb            usb-msc an usb1-2
part  sdb1           usb-msc an sdb

Mount, read, unmount:

md /mnt/stick
mo /dev/sdb1 /mnt/stick
l /mnt/stick
sh /mnt/stick/HALLO.TXT
mo -u /mnt/stick

FAT16 unter /mnt/stick (/dev/sdb1)
HALLO.TXT
Hallo vom USB-Stick

mo with no arguments shows what is currently mounted.

Writing does not work yet. coming soon The stick is read-only:

s: /mnt/stick/neu.txt: Nur lesbares Dateisystem

Packing

arc packs and unpacks archives (tar, zip and others). The format comes from the file extension:

arc sicherung.tar.gz probe
arc -l sicherung.tar.gz
arc -x sicherung.tar.gz ziel

arc -x only overwrites existing files with -f. h arc shows more.