John's Useful Ubuntu Commands Mega-Thread

[John]

John's Useful Ubuntu Linux Commands

Sticky?

cd
Change the working directory.

$ cd /bin

chgrp
Change group ownership of files.

$ chgrp games moo.txt

chmod
Change access permissions of files.

$ chmod +x helloworld

chown
Change file owner and group.

# chown root lorem.txt

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

Sat Mar 3 12:07:09 GMT 2007

df
Reports the amount of disk space used and available on filesystems.

$ df

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

exit
Cause the shell to exit.

$ exit

fgrep
Print lines matching a pattern in a file.

$ fgrep "irure dolor" lorem.txt

find

Search for files in a directory hierarchy.

$ find hello*

hello_world
hello_world.c

free
Display amount of free and used memory in the system.

$ free

grep
Print lines matching a pattern.

$ grep -i apple fruitlist.txt

apple

groups
Outputs the user groups of which your account belongs to.

$ groups

games users

head
Output the first part of files.

$ head -2 lorem.txt

hostname
Outputs the machines hostname on the network.

$ hostname

Johns-Box

id
Outputs user id, group id, and groups of your account.

$ id

uid=1478(smallfoot) gid=100(users) groups=35(games),100(users)

kill
End a process.

$ kill -9 18298

-bash: kill: (18298) - Operation not permitted

killall
Kill processes by name.

$ killall irssi

irssi(18298): Operation not permitted
irssi(13372): Operation not permitted

irssi(22048): Operation not permitted
irssi: no process killed

last
Show listing of last logged in users.

$ last -n 3

ln
Make links between files.

$ ln -s data.txt symlink.txt

logname
Print user's login name.

$ logname

smallfoot

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

nl
Number lines of files.

$ nl lorem.txt

nm
List symbols from object files.

$ nm hello_world

od
Dump files in octal and other formats.

$ od -t x /bin/sh

2376640 00098020 000054d4 00000000 00000000
2376660 00000020 00000000 000000c7 00000008
2376700 00000003 080e6500 0009d4f4 00004ae8

...

pidof
Find the process ID of a running program.

$ pidof fetchmail

22392

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

pstree
Display a tree of processes.

$ pstree

pwd
Outputs the name of current working directory.

$ pwd

/home/smallfoot

rm
Removes a file or directory.

$ rm lorem.txt

rmdir
Removes a directory.

$ rmdir foobar

sed
Stream editor for filtering and transforming text.

$ echo "My cat's name is Bob" | sed -e 's/Bob/Mittens/g'

My cat's name is Mittens

sha1sum
Outputs the SHA1 hash sum of a file.

$ sha1sum lorem.txt

c942ddebd142ec8bacac9213d48096e74bab4957 lorem.txt

shutdown
Bring the system down in a secure way. All logged-in users are notified that the system is going down.

$ shutdown now

size

List section sizes and total size.

$ size /bin/bash

stat
Outputs file status.

$ stat lorem.txt

strings

Print the strings of printable characters in files.

$ strings hello_world

tail
Output the last part of files.

$ tail -2 lorem.txt

talk
Talk to another user.

$ talk bob Lookout for the dopefish!

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

[/QUOTE]/dev/pts/16[/QUOTE]

uname
Outputs operating system, hostname, kernel version, date and timp, and processor.

$ uname -a

Linux Johns-Box 2.6.9 #1 SMP Wed Jul 19 16:24:18 MSD 2006 i686 Intel® Xeon™ CPU 2.80GHz GenuineIntel GNU/Linux

uptime
Outputs the system uptime.

$ uptime

users
Print the user names of users currently logged in to the current host.

$ users

[/QUOTE]alice bob charlie eve[/QUOTE]

vdir
List directory contents.

$ vdir

w
Show who is logged on and what they are doing.

$ w

wall
Send a message to everybody's terminal.

$ wall next week we change the server for a new one

wc
Counts lines in a file.

$ wc -l lorem.txt

7 lorem.txt

whatis
Search the whatis database for complete words.

$ whatis bash

who
Outputs who is currently logged into the system.

$ who

whereis

Locate the binary, source, and manual page files for a command.

$ whereis bash

bash: /bin/bash /etc/bash /usr/share/man/man1/bash.1.gz

whoami
Outputs your username / the name of your account.

$ whoami

[Crow]

fortune

[Acekidd01]

Good commands, but one questions.

The second quote you put in each command means they are like an example of how to do it or a different command with a similar result?

[M0GST3R]

Great post thanks, learning these now in college,cleared a few things up for me.

[John]

Good commands, but one questions.

The second quote you put in each command means they are like an example of how to do it or a different command with a similar result?

Most are examples of what happens when you run the command.

[Gone]

ps|aux One of the ones i use the most.

[Linux]

Good post. I personally have a handbook with most of the linux commands in but this will be useful for beginners to the terminal.