L
Linux Command List
Dunwoody
College of
Technology
11-1-11
Matthew Kerfoot
An A-Z index of the Bash command line for Linux
Page |2
Cd
Changes the Directory
Location:
Syntax: cd [directory]

cd../home/users/computerho
pe
The above example would go
back one directory and then
go into the
home/users/computerhope
directory.

cd ../../
The above example would go
back two directories.

Cd
Cd alone will move you into
the home directory.
Cal
Display a calendar
Location: /usr/bin/cal
Syntax: cal [month] [year]

cal
Gives you the calendar
for this month.

Cal 12 2000
Gives you the calendar
for December of 2000.

cal 1 2011
displays the month of
January, 2011.
Rmdir
Remove folder(s)
Location:/bin/
Syntax:
rmdir [option]…directory…

rmdir /lib
will delete the /lib
directory

rmdir c:\test /s
remove the directory
and all files in it.

Rmdir c:\test –q
will do a quiete
deletion.(no questions
asked.)
Ls
List information about file(s)
Location: /bin/ls
Syntax: ls [-a] [-A] [-b] [-c] [-C] [-d] [-f]
[-F] [-g] [-i] [-l] [-L] [-m] [-o] [-p] [-q] [r] [-R] [-s] [-t] [-u] [-x] [pathnames]

ls/
Lists the documents of your
root directory

ls */
Lists the contents of all sub
directories.

ls –laxo
Lists files with permissions,
shows hidden, displays in a
column format, and doesn’t
show the group.
Man
Help manual
Location:/usr/bin/man
Syntax: man [-] [-k keywords] topic

man –k cal
will seach for the
keyword cal in all
manuals.

man mkdir
lists help information on
the mkdir command.

man –k irc
quickly searches for
manuals containing irc
within them.
Mv
Move or rename files or directories
Location: /bin/mv
Syntax: mv [-f] [-i] oldname
newname

mv oldname newname
Will rename that file in
that directory.

mv –f oldname
newname
Will rename file without
asking you.

mv –I oldname
newname
Will prompt you before
overwriting another file
Pwd
Print Working Directory
Location:/bin/pwd
Syntax: pwd [option]

pwd
Will display /etc in the
prompt.

man pwd
Will display the manual for
the pwd command.

pwd –P
Will print the working
directory, without displaying
all symlinks.

pwd –L
Use pwd from environment,
even if it contains symlinks.
Info
Location: /usr/bin/info
Syntax: info [option] . . . [menuiteam…] [-k] [-d] [-f] [-h]

info info
show the general manual
for info readers

info emacs
start the emacs node
from top-level dir

info –show-options
emacs
Start at node with emacs’
command line options
Who
Print all usernames currently logged in
Location: /usr/bin/who
Syntax: who [option] . . . [file | arg1 arg2]

who –r
Cat
Concatenate and print (display) the
content of files
Location:/bin/cat
Syntax: cat filename [-n] [-b] [-u] [-
Cp
Copy one or more files to another
location.
Location:/bin/co
Syntax: cp [OPTION]... SOURCE
DEST
cp [OPTION]... SOURCE...
DIRECTORY
cp [OPTION]... --targetdirectory=DIRECTORY
SOURCE...

cp file1.txt newdir
Copies the file1.txt in
the current directory to
the newdir directory.

cp *.txt newdir
Copies all files ending
in .txt into newdir
directory.

cp –r
/home/hope.files/*
/home/hope/files2
copies all the files,
directories, and
subdirectories in the
files directory into the
backup directory.
Tar
Tape Archiver
Location: /bin/tar
Syntax: tar c [
bBeEfFhiklnopPqvwX [ 0-7 ] ] [
Uptime
Displays all the time information.
Location: /usr/bin/uptime
Syntax: uptime [-V]

uptime –v
will display the
version information.

uptime
Will display details
about how long your
server has been up and
running, and how
many users are logged
in, and system load
averages for the past 1,
5, and 15 minutes.

Man uptime
Displays the manual
for the uptime
command.
Free
Display memory usage
Location: /usr/bin/free
Syntax: free [-b | -k | -m] [-o] [-s
delay ] [-t] [-V]

free –V
Will display version
information.

free –s
Will switch activates
continuous polling
delay.

free –t
Will switch display
line containing the
totals.

free –b
Will show space in
bytes

free –k
Will display it in
kilobytes.
Vmstat
Report virtual memory statistics
Location: /usr/bin/vmstat
Syntax: vmstat [-V] [-n] [delay
[count]]

vmstat
Running vmstat
command with no
extra options would
display information
about memoty, swap,
io, system, and CPU

vmstat –V
Prints version
information onto
screen.

vmstat –d
Prints disk statistics to
the screen
Id
Print user and group id's
Location: /usr/bin/id
Syntax: id [-a] [-G] [-g] [-u] [user]

info id
Page |3


Will display the run-level of
each user.
who –b
Will indicate the time and
date of the last reboot
who –s
(Default) lists only the name,
line, and time fields.
s] [-v]



cat file1.txt file2.txt >
file3.txt
reads
file1.txt and file2.txt and
combines those files to
make file3.txt.
cat food
will display the cat file to
the screen.
cat eats bird >
detailsat11
Join
the files eat and bird into
detailsat11.
Whoami
Print the current user id and name
Location: /usr/bin/whoami
Syntax: whoami [option]

whoami
will display the name of the
current directory.

If you are logged on as Root
and type whoami it will say
you are logged onto the root
account.

whoami –version
Will output the version
information and exit.

whoami –help
Displays the help and exit
Head
Output the first part of file(s)
Location: /usr/bin/head
Syntax: head [-number | -n number]
filename.

head -15 myfile.txt
will display the first ten
lines of myfile.txt

head myfile.txt
Will show the first 10
lines in myfile.txt

head -n number
Shows the number of
lines you chose for it to
display.
su and/or sux
Substitute user identity(become super
user)
Location: /bin/su
Syntax: su [ - ] [username [arg] ]

su – hope
Login as the user hope, if she
is logged in.

su – hope
This will pass the
environment along unchanged
as if the user actually logged
in as the specified user.

su hope arg
Logs in as hope and additional
arguments that need to be
passed through the su
command.
Tail
Output the last part of files
Location: /usr/bin/tail
Syntax: tail [+ number] [-l] [-b] [-c]
[-r] [-f] [-c number | -n number]
[file]

tail myfile.txt
The above example
would list the last 10
(default) lines of the file
myfile.txt.

tail –f myfile.txt
Displays the last 10 lines
and then update the file
as new lines are being
added. This is a great
command to watch log
files or logs in real-time.

tail –f access.log |grep
24.10.160.10
Allows you to watch the
access.log foe any IP
address of 24.10.160.10
block ] [ tarfile ] [ exclude-file ] {-I
include-file | -C directory | file | file
}
tar r [ bBeEfFhiklnqvw [ 0-7 ] ] [
block ] {-I include-file | -C
directory | file | file }
tar t [ BefFhiklnqvX [ 0-7 ] ] [
tarfile ] [ exclude-file ] {-I includefile | file } ...
tar u [ bBeEfFhiklnqvw [ 0-7 ] ] [
block ] [ tarfile ] file ... tar x [
BefFhiklmnopqvwX [ 0-7 ] ] [
tarfile ] [ exclude-file ] [ file ... ]

Tar –cvwf file.tar
myfile.txt
Creates a tar
named file.tar in
the directory
you are
currently in.

-xvwf myfile.tar
Uncompress
(untar) the myfile.txt
file in
the current
directory.

Tar –xvwzf
myfile.tar.gz
Uncompress the
myfile.tar.gz
file in the current
directory.
Gzip
Compress or decompress named
file(s)
Location: /usr/bin/gzip
Syntax: gzip [ -acdfhlLnNrtvV19 ]
[-S suffix] [ name ... ]
gunzip [ -acfhlLnNrtvV ] [-S
suffix] [ name ... ]
zcat [ -fhLV ] [ name ... ]
bzip/bzip2
Compress or decompress named
file(s)
Location: /usr/bin/bzip2
Syntax: bzip2 [cdfkqstvuzVL123456789]
[filenames. . .]

bzip2 –f [filename]
Forces overwrite of
output files.

bzip2 –t filname
Check integrity of the
specified files, but don’t
decompress them.

bzip2 –q filename
suppress non-essential
warning messages. Will
still display I/O errors.


Should give you
access to the complete
manual.
id –g
Print only effective
group ID.
id –G
Prints all group IDs
Shutdown
Shutdown or restart linux
Location: /sbin/shutdown
Syntax: shutdown [-a][-t sec][krhnfFc][time][warning-message]

shutdown 8:00
Shutdown computer at
8-oclock

shutdown –t sec
Tells init to wait sec
seconds between
sending processes the
warning and the kill
signal, before
changing to another
run-level.

shutdown –h
Halts after shutdown.
Halt
Reboot, poweroff – stop the
Location: /sbin/halt
Syntax: halt [-l] [-n] [-q] [-y]
or
halt [-n] [-w] [-d] [-f] [-i] [-p] [-h]
reboot [-n] [-w] [-d] [f] [-i]
poweroff [-n] [-w] [-d]
[-f] [-i] [-h]

halt
Set the computer to a
mode that enables a
user to turn off the
computer.

halt –q
Quick halt. No
graceful shutdown
required.

halt –l
Suppresses sending a
message to the system
log deamon, syslogd,
about who executed
halt.

poweroff
Stops the processor (if
Page |4
you have the right
permissions).
Whatis
Display manual page descriptions.
Location: /usr/bin/whatis
Syntax: whatis [-dlhV] [-r|-w] [-s section]
[-m system[,…]] [-M path] [-L locale] [C file] name…

whatis –d
prints debugging information
to the screen.

whatis –M manpath –w ‘*’ |
sort > manpath/whatis
Produces an old style text
whatis database from relative
index database.

whatis –V
Will display the version
information to the output of
the monitor.
Whereis
Search the user's $path, man pages and
source files for a program
Location:/usr/bin/whereis
Syntax: whereis [ -bmsu ] [ -BMS
directory... -f ] filename ...



whereis –b
Searches only for binaries.
whereis –m
Searches only for manual
sections.
whereis –s
Searches only for sources.
Which
Search the user's $path for a program file
Location: /usr/bin/which
Syntax: which [ filename ] ...

which pearl
Would locate the executable
location of the pearl command

which -a
prints all matching
executables in PATH, not just
the first one.

which() { declare –f |which –
read-functions $@ }
Will read shell function
definitions from stdin,
reporting matching ones on
Less
Display output one screen at a time
Location: /usr/bin/less
Syntax: less -?
less --help
less -V
less --version
less [[+]aBcCdeEfFgGiIJmMn
NqQrRsSuUVwWX]
[-b space] [-h lines] [-j
line] [-k keyfile]
[-{oO} logfile] [-p
pattern] [-P prompt] [-t tag]
[-T tagsfile] [-x tab,...] [-y
lines] [-[z] lines]
[+[+]cmd] [--]
[filename]...

less –j
Displays the status
column at the left edge of
the screen.

less –V
Displays the version
number of less.

less table1
Will display the top of
file table1
More
Display output one screen at a time
Location: /bin/more
Syntax: more [-c] [-d] [-e] [-f] [-i] [l] [-n number] [-p command] [-r] [-s]
[-t tagstring] [-u] [-w] [ -lines ] [ +
linenumber ] [ +/ pattern ] [ file ... ]

more –c
Clear before displaying.
Redraws the screen
instead of scrolling for
faster displays.

more –e
Exit immediately after
writing the last line of the
last file in the argument
list.

more –i
Perform pattern matching
in searches without
regard to case.
Grep
Search file(s) for lines that match a
given pattern
Location: /usr/bin/grep
Syntax:
grep [options]
PATTERN [FILE...]
grep [options] [-e
PATTERN | -f FILE] [FILE...]

grep –a
Processs a binary file as
if it were text; this is
equivalent to the—
binary-files=text option

grep –b
Prints the byte offset
within the input file
before each line of the
output.

grep –V
Prints the version
number of grep to
standard error.
Kill
Stop a process from running
Location: /bin/kill
Syntax: kill [-s] [-l] %pid

kill –s
Specify the signal to
send.

kill –l
Write all values of
signal supported ny the
implementation.

kill –pid
You can specify a
decimal integer which
specifies a process or
group of processes, or
a job control ID that
identifies a
background process
group to be signaled.
Ln
Make links between files
Location: /bin/ln
Syntax: ln [-f] [-n] [-s] existingfile
newname

ln –n
Will not overwrite
existing files.

ln –s
Makes it so that it does
not create a symbolic
link existing file – the
file that you want to
create a link to.

ln –f
Will link files without
questioning the user,
even if the mode of the
target forbids writing.
This is default in the
standard input is not a
terminal.
Vi
Text Editor
Location: /usr/bin/vi
Syntax: vi [ -| -s ] [-l] [-L] [-R] [ -r [
filename ] ] [-S] [-t tag] [-v] [-V] [-x]
[-w] [-n ] [-C] [+command | -c
command ] filename

vi myfile.txt
Will edit the file
myfile.txt

vi- | -s myfile.txt
Suppress all interactive
user feedback. this is
useful when processing
editor scripts

vi –R myfile.txt
Type
Describe a command
Location: a shell builtin
Syntax: touch [-a] [-c] [-m] [-r
ref_file | -t time ] file
settime [ -f ref_file ] file

touch newfile.txt
Creates a file
known as :newfile.txt”,
if the file does not
already exists. If the file
already exists the
accessed / modification
time is updated for the
file newfile.txt

touch –a myfile.txt
Ifconfig
Configure a network interface
Location: /sbin/ifconfig
Syntax: ifconfig [-L] [-m]
interface [create]
[address_family]
[address[/prefixlength]
[dest_address]]
[parameters]
ifconfig interface
destroy
ifconfig -a [-L] [-d] [m] [-u] [address_family]
ifconfig -l [-d] [-u]
[address_family]
ifconfig [-L] [-d] [-m]
[-u] [-C]

ifconfig add
Another name for alias
parameter.

ifconfig –interface
This parameter is a
string of the form ‘ ‘
name unit”’ for
example, ‘ ‘ en0”.

ifconfig remove
Another name for the –
alias parameter.
Alias
Create an alias
Location: a shell builtin
Syntax: alias [name=['command']]

alias home ‘cd
public_html’
Sets home to type cd
public_html

alias
this command by itself
lists all the aliases we
have created.

alias ll
alias ll=’ls –l’
Will show a long
colored listing of all
Page |5
stdout.
readonly mode; the
readonly flag is set,
preventing accidental
overwriting of the file.

Will change the access
time of the file. Do not
write any diagnostic
messages concerning
this condition.
settime myfile.txt
Sets the file myfile.txt
as the current time/date.
Find
Search for files that meet a desired
criteria
Location: /usr/bin/find
Syntax: find path expressions

find –name “MyCPrgram.c”
Finds files using names,
displays files and
subdirectories.

find –iname
“MyCProgram.c”
Finds files using name and
ignoring case.

find . –type -F –exec ls –s {}
\; | sort –n –r |head -5
Finds the top 5 biggest files in
the current directory and its
subdirectories.
Touch
Change file timestamps
Location: /usr/bin/touch
Syntax: touch [option] . . . file . . .

touch myfile.txt
just updates the
timestamp of the file to
the computer’s current
date and time.

touch project.c
will simulate an update to
project.c

touch myfile.txt –a
changes only the access
time.
Ping
Test a network connection
Secure Shell client (remote login
program). Sends ICMP
ECHO_REQUEST packets to
network hosts.
Location: /bin/ping
Syntax: ping -s [-d] [-l] [-L] [-n] [r] [-R] [-v] [ -i interface_address ]
[-I interval] [-t ttl] host [packetsize]
[count]

ping –I 0.1 IP
Decreases ping internal
time. (Wait 0.1 seconds
before sending the next
packet.)

ping –l 5600 –s 100 -i
0.1 192.168.15.200
pretty much ping of
death, increases variable
time, and increases
packet size.

ping 127.0.0.1
Pings local host.
Date
Display or change the date & time
Location: /bin/date
Syntax: date [-a] [-u] [-s datestr]

date
List the date and time of the
server. for example
Thu Feb9 16:47:32 MST 2011

date –s “11/20/2003
12:48:00”
Set the date and time shown

date
‘+DATE:%m/%d/%y%nTI
ME:%H:%M:%S’
Would list the time and date
in the below format.
DATE: 02/08/01
TIME:16:44:55
Mkdir
Create new folder(s)
Location: /bin/mkdirwhich
Syntax: mkdir [-m,-p,-v,-z,or
directory name] directory

mkdir mydir
The above command
creates a new directory
called mydir.

mkdir –m a=rwx mydir
This example would use
the –m option to not only
create the mydir directory
but also set the
permissions to all users
having read, write, and
execute permissions

mkdir –v bigdir
Will display a message
for each created directory
Uname
Print system information
Location: /bin/uname
Syntax: uname [-a] [-i] [-m] [-n] [p] [-r] [-s] [-v] [-x] [-S
systemname]

uname –arv
Will list the basic
system information, OS
release, and OS version.

uname –p
Will display the Linux
platform.

uname –a
Will print out all
information.

uname –v
Will print out the kernel
version.
~
tilde
the tilde represents the home directory of the
current user.

~foo
Refers to the home directory of the
user
foo.
>
Redirector
Redirects a file to a different output.

date > RightNow.txt
.> is used to replace the
of any existing file having the name
“RightNow.txt”.
content
the created aliases.
Ssh
Secure Shell client (remote login
program)
Location: /usr/bin/ssh
Syntax: ssh [1246AaCfgkNnqsTtVvXxY] [-b
bind_address] [-c cipher_spec] [D port] [-e escape_char] [-F
configfile] [-i identity_file] [-L
port:host:hostport] [-l
login_name] [-m mac_spec] [-o
option] [-p port] [-R
p_rt:host:hostport]
[user@]hostname [command]

ssh –V
Identifies SSH client
version.

ssh –l jsmith
remotehost.example.co
m
Login to remote host.
(ssh-keygen –F
publickey.pub) to get
public key
fingerprints.

scp
jsmith@remotehost.e
xample.com:/home/js
mith/localhostfile.txt
Copies the file from
the remote host to the
local host.
Rsync
Remote file copy (Synchronize
file trees)
Location: /usr/bin/rsync
Syntax: rsync options source
destination

rsync –zvr
/var/opt/installation/i
nventory/ /root/temp
-z is to enable
compression
-v verbose
-r indicates recursive
Syncs two directories
in a local computer.

rsync –azv
/var/opt/installation/i
nventory/ /root/temp/
Archives the file too.

rsync –v
/var/lib/rpm/Pubkeys
/root/temp/Pubkeys
Copies one file.
?
Question mark
Expands to the status of the most recently executed
foreground pipeline.

man -?
Displays the man help list
Page |6
.
period
Run a command script in the current shell
(current directory)

./filename
refers to a filename in the current
directory.
>>
append
to overwrite an existing file use “>>” to append to
any existing file.

date >> RightNow.txt
Will attach the information about the
date to the file RightNow.txt.
..
Parent directory
Runs a command script in the current shell.

../filename
Means you are referring to a
filename in parent directory.
<
Backwards redirector
Redirects output to a different input.

Sort < txtfile
is the same as
cat textfile | sort
|
pipeline
A pipeline is used to make the output of one
command serve as the input to another command.

echo ”cherry apple peach” |tr “ “
“\n”
pipes the output of echo into
translation command which
spaces with linefeeds, represented
by “\n”
*
Asterisk
Expands to the positional parameters, starting from
one. When the expansion occurs within double
quotes, it expands to a single word with the value
of each parameter separated by the first character
of the IFS special variable.

ls *
will display all directories and files.
Page |7
References
(2011) Computer Hope. Linux Command Help. http://www.computerhope.com/unix/usu.htm
(2009) The Geek Stuff. Linux Commands. http://www.thegeekstuff.com/2009/11/ping-tutorial-13-effective-ping-command-examples/