This short guide shows some important commands for your daily work on the Linux command line.
arch
Outputs the processor architecture.
$ arch
i686
cat
Outputs the contents of a file.
$ cat lorem.txt
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
cd
Change the working directory.
$ cd /bin
cksum
Print CRC checksum and byte counts of each file.
$ cksum lorem.txt moo.txt
3570240675 453 lorem.txt
4294967295 0 moo.txt
cp
Copies a file.
$ cp lorem.txt copy_of_lorem.txt
date
Outputs the current date and time.
$ date
Ads_kid=0;Ads_bid=0;Ads_xl=0;Ads_yl=0;Ads_xp=”;Ads_yp=”;Ads_xp1=”;Ads_yp1=”;Ads_opt=0;Ads_wrd='[KeyWord]’;Ads_par=”;Ads_cnturl=”; function Ads_PopUp() {}
Sat Mar 3 12:07:09 GMT 2007
df
Reports the amount of disk space used and available on filesystems.
$ df
Filesystem 1K-blocks Used Available Use% Mounted on<br>
/dev/simfs 39845888 218048 39627840 1% /
dir
List directory contents.
$ dir
copy_of_lorem.txt lorem.txt moo.txt www
du
Estimate file space usage.
$ du -h /bin
7.8M /bin
echo
Display a line of text.
$ echo foobar
foobar
fgrep
Print lines matching a pattern in a file.
$ fgrep “irure dolor” lorem.txt
commodo consequat. Duis aute irure dolor in reprehenderit in voluptate
groups
Outputs the user groups of which your account belongs to.
$ groups
games users
hostname
Outputs the machines hostname on the network.
$ hostname
anapnea.net
id
Outputs user id, group id, and groups of your account.
$ id
uid=1478(smallfoot) gid=100(users) groups=35(games),100(users)
ls
List directory contents.
$ ls
copy_of_lorem.txt lorem.txt moo.txt www
man
Opens the manual page for a software or function.
$ man bash
md5sum
Outputs the MD5 hash sum of a file.
$ md5sum lorem.txt
56da9e37259af34345895883e6fd1a27 lorem.txt
mkdir
Makes a directory.
$ mkdir foobar
mv
Moves a file.
$ mv lorem.txt ipsum.txt
ping
Pings a host.
$ ping -c 2 127.0.0.1
PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data.
64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.048 ms
64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.052 ms
— 127.0.0.1 ping statistics —
2 packets transmitted, 2 received, 0% packet loss, time 999ms
rtt min/avg/max/mdev = 0.048/0.050/0.052/0.002 ms
ps
Outputs running processes.
$ ps
PID TTY TIME CMD
21542 pts/12 00:00:00 bash
27706 pts/12 00:00:00 ps
pstree
Display a tree of processes.
$ pstree
init-+-2*[BitchX]
|-3*[bash—sleep]
|-fetchmail
|-screen-+-bash—irssi
| `-bash—ctorrent
|-screen-+-bash—lisp.run
| |-bash—vi
| |-2*[bash]
| `-bash—lynx
|-2*[screen—bash—irssi]
|-screen—irssi
|-screen—bash
|-screen-+-bash
| `-irssi
|-skjerm—irssi
|-sshd-+-5*[sshd—sshd—bash—irssi]
| |-8*[sshd—sshd—bash]
| |-sshd—sshd—bash—screen
| |-sshd—sshd
| `-sshd—sshd—bash—pstree
`-syslog-ng
pwd
Outputs the name of current working directory.
$ pwd
/home/smallfoot
sha1sum
Outputs the SHA1 hash sum of a file.
$ sha1sum lorem.txt
c942ddebd142ec8bacac9213d48096e74bab4957 lorem.txt
stat
Outputs file status.
$ stat lorem.txt
File: `lorem.txt’
Size: 453 Blocks: 8 IO Block: 4096 regular file
Device: 77h/119d Inode: 27312217 Links: 1
Access: (0644/-rw-r–r–) Uid: ( 1478/smallfoot) Gid: ( 100/ users)
Access: 2007-03-03 12:24:39.000000000 +0000
Modify: 2007-03-03 12:24:39.000000000 +0000
Change: 2007-03-03 12:24:39.000000000 +0000
rm
Removes a file or directory.
$ rm lorem.txt
rmdir
Removes a directory.
$ rmdir foobar
touch
Change a file’s access and modification timestamps. If file does not exist, create it.
$ touch lorem.txt
tty
Outputs the name of the current terminal.
$ tty
/dev/pts/16
uname
Outputs operating system, hostname, kernel version, date and timp, and processor.
$ uname -a
Linux anapnea.net 2.6.9 #1 SMP Wed Jul 19 16:24:18 MSD 2006 i686 Intel(R) Xeon(TM) CPU 2.80GHz GenuineIntel GNU/Linux
uptime
Outputs the system uptime.
$ uptime
14:50:26 up 7 days, 17:52, 18 users, load average: 0.08, 0.02, 0.01
users
Print the user names of users currently logged in to the current host.
$ users
alice bob charlie eve
vdir
List directory contents.
$ vdir
total 8
-rw-r–r– 1 smallfoot users 453 Mar 3 12:32 copy_of_lorem.txt
-rw-r–r– 1 smallfoot users 453 Mar 3 12:24 lorem.txt
-rw-r–r– 1 smallfoot users 0 Mar 3 12:32 moo.txt
lrwxr-xr-x 1 root root 18 Feb 27 19:33 www -> /var/www/smallfoot
w
Show who is logged on and what they are doing.
$ w
12:14:30 up 5 days, 15:16, 19 users, load average: 0.00, 0.00, 0.00
USER TTY LOGIN@ IDLE JCPU PCPU WHAT
charlie pts/0 Fri21 3:26m 2.52s 2.52s irssi
alice pts/2 Wed17 30:21m 0.00s 0.00s -bash
emma pts/4 11:37 36:57 0.00s 0.00s -bash
frank pts/5 11:48 11:03 0.00s 0.00s -bash
smallfoo pts/12 12:01 0.00s 0.04s 0.01s w
wc
Counts lines in a file.
$ wc -l lorem.txt
7 lorem.txt
who
Outputs who is currently logged into the system.
$ who
charlie pts/0 Mar 2 21:37 (xtreme-11-65.acme.com)
alice pts/2 Feb 28 17:48 (147.21.16.3)
emma pts/4 Mar 3 11:37 (32.84-48-181.uac.com)
frank pts/5 Mar 3 11:48 (port-212-202-233-2.foobar.org)
smallfoot pts/12 Mar 3 12:01 (c-12776f4.cust.example.net)
whoami
Outputs your username / the name of your account.
$ whoami
smallfoot
