Basic Linux/Unix Commands
# session & environment
tty reveals the current terminal whoami reveals the current log-in user which reveals where in the search path a program is located echo $PATH prints to the screen; dumps the current path to STDOUT set prints and optionally sets variables clear clears the screen buffer history reveals the command history cd ~ user's $HOME directory in BASH pwd print the current working directory cd change directory to desired directory su switch users — with no option, attempts to log in as root w reveals connected terminals i.e 'pts/0…N' and/or 'tty1..N' Tips: Up/Down arrows navigate command history. BASH supports tab completion — type unique characters and press TAB. In GNOME terminal: left button to block, right button (or Ctrl-Shift-V) to paste.
# files & directories
ls lists directories and files cat concatenates files mkdir creates a new directory cp copies files mv moves files rm removes files/directories touch create blank file / updates time-stamp stat reveals statistics of files find finds files using search patterns alias returns / sets aliases for commands file determines file type # viewing text
more pagination — displays text one page at a time less like more, e.g. less 1thousand.txt head display opening lines of text files (first 10 lines) tail display the closing lines of text wc -l count words and optionally lines of text files seq 1000 > 1thousand.txt echoes a sequence of numbers into a file # networking
ping send ICMP ECHO_REQUEST to network hosts ifconfig configure the kernel-resident network interfaces netstat print network connections, routing tables, interface statistics and more hostname show or set the system's host name ssh OpenSSH SSH client (remote login program) ftp Internet file transfer program sftp secure file transfer program # system & processes
uname -a returns OS, FQDN, kernel version and kernel compile date/time top display Linux processes ps report a snapshot of the current processes mount mount a filesystem df report file system disk space usage swapon -s display summary of used swap devices runlevel output previous and current runlevel chroot run command or interactive shell with special root directory init Upstart process management daemon shutdown bring the system down reboot reboot or stop the system (also: halt, poweroff) login begin session on the system passwd change user password fdisk manipulate disk partition table # permissions
chmod change file mode bits chown change file owner and group # editors & tools
vim Vi IMproved, a programmers text editor nano Nano's ANOther editor, an enhanced free Pico clone gedit text editor for the GNOME Desktop bc an arbitrary precision calculator language