What follows is a list of port names and services that correspond to the
most commonly used Unix and Linux services.

SERVICE							Port(s)
Echo 							7
Daytime 						13
qotd (Quote Of The Day) 				17
FTP-data 						20
FTP 							21
SSH 							22
Telnet 							23
SMTP (Simple Mail Transfer Protocol) 			25
Time server 						37
Whois 							43
DNS (Domain Name System) 				53
TFTP (Trivial File Transfer Protocol) 			69
Finger 							79
HTTP (Hypertext Transfer Protocol) 			80

POP2 (Post Office Protocol 2) 				109
POP3 (Post Office Protocol 3) 				110
Portmapper 						111
Ident 							113
NNTP (Network News Transfer Protocol) 			119
NTP (Network Time Protocol) 				123
Samba 							137–139
IMAP2 (Internet Message Access Protocol) 		143
SNMP (Simple Network Management Protocol) 		161
BGP (Border Gateway Protocol) 				179
IMAP3 (Internet Message Access Protocol) 		220
LDAP (Lightweight Directory Access Protocol) 		389
HTTPS (Secure Hypertext Transfer Protocol) 		443
rlogin 							513
rsh 							514
Line printer (lpr) spooler 				515
Talk 							517
Time server 						525
NNTPS (Secure Network News Transfer Protocol) 		563
IPP (Internet Printing Protocol) 			631
LDAPS (Secure Lightweight Directory Access Protocol) 	636
IMAPS (Secure Internet Message Access Protocol) 	993
POP3S (Secure Post Office Protocol) 			995
NFS (Network File System) 				2049
MySQL 							3306
VNC (Virtual Network Computing) 			5800+
							5900+
X11 							6000–6063
XFS (X Font Server) 					7100

What follows is a list of most common commands that can be found onbare-bones installations of most Unix and Linux distributions. For more information on a particular command, see its manual page by typing man <command>.

Command			Description
alias			Set & view command aliases
arch			print machine architecture
awk			pattern scanning & processing language
bash			Bourne again shell
bg			move process running in foreground to the background
biff			be notified when mail arrives
cat			concatenate & print files
cd			change directory
change			change user password expiry information
chgrp			change group ownership
chmod			change file permission
chown			change file & group owner
chroot			run command with special root directory
chsh			change login shell
clear			clear the terminal screen
cp			copy files & directories
crontab			maintain crontab files
csh			C shell
cut			remove sections from each line of files

date			print or set the system date & time
dd			convert & copy a file
df			print file-system disk space usage
diff			find differences between files
dig			DNS (Domain Name System) lookup utility
dmesg			Print diagnostic messages from system buffer
dnsdomainname		show system's DNS (Domain Name System) domain name
domainname		show system's NIS (Network Information System)
			or YP (Yellow Pages) name
du			Estimate file space usage
echo			Display a line of text
env			Run a program in a modified environment
false			exit with a status code indicating failure
fdisk			disk partition table manipulator
fg			move process running in background to the foreground
file			determine file type
find			search for files in a directory hierarchy
free			display amount of free and used system memory
ftp			FTP client
fuser			identify processes using files or sockets
gcc			GNU C and C++ compiler
grep			Print lines matching a given pattern
groupadd		creade a new group
groupdel		delete a group
groupmod		modify a group
groups			print all the groups the user belongs to
gunzip			uncompress files compressed using Lempel Ziv encoding
gzip			compress files using Lempel Ziv encoding
host			DNS lookup utility
hostname		show or set system hostname
history			show history of commands that given to terminal/konsol
id			print real and effectife user IDs and group IDs
ifconfig		configure a network interface
kill			terminate a process
ksh			korn shell
last			show listing of last logged in users
lastlog			show last login times of accounts
ln			make links between files
ls			list directory content
mail			send and receive mail
man			format dan display manual pages
mesg			control write access to a terminal
mkdir			make directories
more			display file contents, one screenful at a time
mount			mount a file system
mv			move and rename files and directories
netstat			print network connections, routing tables, interface statistic
			masquerade connections, and multicast membership
nice			run a program with modified scheduling priority
nslookup		query internet name servers
passwd			change login and password attributes
ping			send ICMP ECHO_REQUEST to network hosts
ps			report process status
pwd			print name of working directory
quota			display disk usage and limits
quotaoff		turn off file-system guotas
quotaon			turn on file-system quotas
rapquota		summarize quotas for file system
rm			remove files or directories
rmdir			remove empty directories
route			show or manipulate system routing table
rcpinfo			report RPC(Remote Procedure Call) information
sed			stream editor
setquota		set disk qoutas
showmount		show mount information for an NFS(Netwok File System) server.
shutdown		bring the system down
sleep			delay for a specified amount of time
sort			sort lines of text files
strace			trace system calls and signals
strings			print printable characters in files
su			run a shell with substitute user and groups IDs
tail			output the last part of files
tar			archiving utility
tcsh			c shell with filename completion and command editing
telnet			telnet client
tftp			tftp (Trivial File Transfer Protocol) client
traceroute		print the route that packets take to a destination host
true			exit with a status code indicating success
umount			unmount a files system
uname			print system information
useradd			create a new user
userdel			delete user account
uptime			print how long the system has been running
vi			text editor
w			show users that are logged on and what they are doing
wall			send message to every user's terminal
wc			print the number of bytes, words, and lines in files
whereis			locate the binary, source, and manual page files for a command
which			show the full path of command
who			show users that are logged on
whoami			print effective user ID
write			send a message to another user
ypdomainnam		show or system's NIS (Network Information System) or YP
			Yellow pages domain name.