Some basic and common Commands
# cd - * Go to previous directory
# cd * Go to $Home directory
# (cd <dir> && <command> ) * Go to dir, execute command and return to current dir
# ls * Lists the contents of a Directory
# pwd * Display Current Directory
# cal * Display calendar.
# cat * The cat command reads one or more files and prints them to standard output.
# wc * Display Number of line, words, bytes.
# tty * Print the file name of the terminal connected to standard input synopsis.
# passwd * Changing the password or user.
# bc * Basic calculator language. ( For exit use Ctrl+d )
# mkdir * Make Directory
# rmdir * Remove empty directory
# cp * copy files and directory.
# rm * Deleting filename
# mv * move or rename files
# od * Dump file in octal and other formats
# which <command > * Show full path name of command
# time < command > * See how long a command takes.
# time cat * Start stopwatch. Ctrl-d to stop. See also sw
#tar -cvf <filename.tar> <source> * Create a backup file.
#tar -xvf <filename.tar> * Restore backup file.
#gzip <filename.tar> * Create compress file
#unzip <filename.tar.gz> * Restore compress file
#bzip2 <filename.tar> * Create compress file.
#bunzip2 <filename.bz2> * Restore compress file
# man -t ls | ps2pdf - > ls.pdf * make a pdf file of a manual page.
# gpg -c < file name > * Encrypt file
# gpg <file-name.gpg> * Decrypt file
# ethtool eth0 * Show status of Ethernet interface eth0
# iwconfig eth1 * show status of wireless interface eth1
# iwlist * scan list wireless networks in range
# ip link show * list network interface
# ip link set dev eth0 * name wan Rename interface eth0 to wan
# ip link set dev eth0 up * Bring interface eth0 up (or down)
# ip addr show * List addresses for interfaces
# ip route show * List routing table
# ip route add default via 1.2.3.254 * Set default gateway to 1.2.3.254
# host pixelbeat.org * Lookup DNS ip address for name or vice versa
# netstat -tupl * List internet services on a system
# netstat -tup * List active connections to/from system
# tail -f /var/log/messages * Monitor messages in a log file
# tcpdump not port 22 * Show network traffic except ssh.
# uname -a * Show kernel version and system architecture
# cat /proc/partitions * Show all partitions registered on the system
# grep MemTotal /proc/meminfo * Show RAM total seen by the system
# grep "model name" /proc/cpuinfo * Show CPU(s) info