John Topley's Knowledgebase

Useful Linux/UNIX Commands

Friday, 30 May 2003

The following is a list of useful commands for accomplishing various tasks with Linux/UNIX.

Use these commands to:

Save manual page for name in ASCII format to filename:

man name | col -b > filename

Display all pages for name:

man -a name

Search man pages for keyword:

man -k keyword

Change pager used by man e.g. less:

man -P pagername

Start a new login session for username:

exec login username

Display login name:

logname

Logout:

Ctrl + D

Change username's password:

passwd username

Undo last directory change:

cd -

Go to home directory:

cd ~

Display current directory:

pwd

Change filename's modification time to current time:

touch filename

Display number of characters, words and lines in filename:

wc filename (wc -c, wc -w, wc -l)

Display disk space used:

du (du -a, du -s)

Identify file type of file filename:

file filename

Display disk space allocated to username:

quota (quota -v, quota -g, quota -g., quota username)

List all files beginning with foo:

ls foo*

List all files ending with .bar:

ls *.bar

List all files ending with a period and a single character:

ls *.?

List all files beginning with f or b:

ls [fb]

List all files beginning with a letter in the range b to f:

ls [b-f]*

List all files beginning with foo:

ls foo*

Find the largest file in the current directory:

ls -l | cut -c33-42 | sort -nr | head -1

Mount drive C: as FAT at /mnt/c:

mount -t msdos /dev/hda1/mnt/c:

Mount CD-ROM at /mnt/cdrom:

mount -t iso9660 /dev/hdc/mnt/cdrom

Unmount drive at mnt/foo:

umount /mnt/foo

Format a floppy disk:

fdformat /dev/fd0H1440

Create ext2 filesystem on a floppy disk:

mkfs -t ext2 -c /dev/fd0H1440

Display a list of running processes:

ps (ps -f, ps -l)

Run commands as a background process:

bg commands

Run process as a foreground process:

fg process

Leave command running after logoff:

nohup command &

List available kill signals:

kill -l

Determine what signal terminated the previous shell command:

kill -l $?

Display environment settings:

env

Display date and time:

date

Display a list of logged on users:

finger

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