Favorite Linux Command

Connect:

telnet [host]   [port]                    Connect to host (25 (SMTP), 109/110 (POP3), 21 (FTP), 20 (FTP data) )
ssh -l [user] [host]                      Secure telnet to host

 

Connect info:

who                                 Who is connected
finger [-l @host]                   Display info about logged on users
finger [user]                       Display info about user
whois [-h host name]                Scans for a name or handle
whoami                              Display the effective current username

 

Network:

nslookup                            Query domain name servers interactively
route                               Routing (add host/net target gateway 0)
netstat -a|more                         Routing table. Show network status
ifconfig [device]                   Show the stats of network device, or all devices: -a
traceroute [ip_address]               Tracing IP packet from this host to destination

Jobs:

ps                                  List current processes (ps -aef | grep $USER)
CTRL + Z                            Suspend
kill [pid] / CTRL + C               Kill a job (use pid returned by ps; -9 exit immediately)

 

Directories:

pwd                                 Display the pathname of the current working directory
cd [dirname]                        Change to directory dirname (cd without dirname wil go to your home
                                    directory, cd .. moves one directory up, cd ~username moves you to
                                    username’s homedir)
mkdir                               Make directory
rm, rmdir [dirname]                 Remove (unlink) files or directories
ln -s [realpath alias]              Make symbolic links to files
df -h                              Report free disk space on file systems
fsck                                File system consistency check and interactive repair