Basic Linux Commands

ls – List directory contents

• Lists files, directories
• For long output, pipe through more: > ls -l | more

(use q or Ctrl-c to exit)

grep – Find text in a file

• grep PATTERN [FILE]
• > grep failed auth.log

cd – Change current directory

• Nearly identical to Windows command line
• Forward slashes instead of backward
• cd <directory>
• > cd /var/log

shutdown – Shut the system down

• sudo shutdown 2
• Shuts down and turns off the computer in two minutes
• sudo shutdown -r 2
• Shuts down and reboots in two minutes
• Ctrl-C to cancel

pwd – Print Working Directory

• Displays the current working directory path
• Useful when changing directories often

passwd – Change a user account password

• passwd

mv – Move (rename) a file

• mv SOURCE DEST
• > mv first.txt second.txt

cp – Copy a file

• cp SOURCE DEST
• > cp first.txt second.txt

rm – Remove files or directories

• Does not remove directories by default
• Directories must be empty or must be removed with -r

mkdir – Make a directory

• mkdir DIRECTORY
• > mkdir notes

chmod – Change mode of a file system object

• r=read, w=write, x=execute
• Can also use octal notation
• Set for the file owner (u), the group(g), others(o), or all(a)
• chmod mode FILE
• > chmod 744 script.sh

chown – Change file owner and group

• sudo chown [OWNER:GROUP] file
• > sudo chown professor script.sh

iwconfig – View or change wireless network configuration

• Requires some knowledge of the wireless network
• iwconfig eth0 essid studio-wireless

ifconfig – View or configure a interface and IP configuration

• ifconfig eth0

ps – View the current processes

• Similar to the Windows Task Manager
• View user processes – ps
• View all processes – ps -e | more

su – Become super user

• You continue to be that user until you exit

sudo – Execute a command as the super user

• Only that command executes as the super user

apt-get – Advanced Packaging Tool

• Handles the management of application packages
• > sudo apt-get install wireshark

vi – Visual mode editor

• Full screen editing with copy, paste, and more
• vi FILE
• > vi script.sh
• Insert text – i <text>
• Exit insert mode with Esc
• Save (write) the file and quit vi – :wq

dd – Convert and copy a file

• Backup and restore an entire partition
• > dd if=<src file name> of=<target file name> [Options]
• Creating a disk image
• > dd if=/dev/sda of=/tmp/sda-image.img
• Restoring from an image
• > dd if=/tmp/sda-image.img of=/dev/sda