User/Permission
sudo <command>
sudo = Super-User-DO
Run command as root user
sudo su
su = Super User/Switch User
To open a shell as another user (including root)
su - user2
To switch user to user2
whoami
To get current user name
chmod
changes the file mode (permission) of each given file/folder
sudo chmod 777 abc.sh
chown
change file owner and group
sudo chown username:group directory
change all file and folders recursively
sudo chown -R username:group directory
File/Directory
ls
List the contents of the folder
ls -la
list in long listing fashion + hidden files
mkdir
To create a new directory
cd path
to change directory.
cd /home/techbrij/projects
to go in parent directory
cd ..
to go in user home directory
cd ~
touch
create file if not exists, update timestamp if file exists.
touch myfilename.sh
cat
displays a file content
cat pq.txt
displays a file content with line numbers
cat -n pq.txt
join two or more plain file
cat p.txt q.txt >> pq.txt
cp [options] source dest
to copy files and directories.
cp myFile.txt /home/techbrij/
recursive copy (including hidden files):
cp -R devFolder bakFolder
mv [options] source dest
Move all txt files in current directory to subdirectory bak
mv *.txt bak
Rename directory brij to techbrij:
mv brij techbrij
tail [options] [filenames]
By default, tail returns the final ten lines of the file
tail techbrij.txt
to print the final 15 lines
tail -15 techbrij.txt
System/Application
date
print the current date and time
to set date time
date --set='21 may 2016 13:57'
ps
shows all of the processes associated with the current user and terminal session
To get a more complete picture of the processes
ps aux
To search the process list
ps -ef | grep searchkeyword
ps -ef | grep node
pgrep
to get the PID of a process
pgrep bash
pgrep -f 'ssh example.com'
kill <pid>
to kill process
kill -9 2405
kill -9 'pgrep ping'
nohup command-name &
To run command in background
nohup myscript.sh &
apt
apt = Advanced Package Tool
To install myPackage
apt-get install myPackage
To update packages
apt-get update
tar
To create tar.gz archive file
tar cvzf Myfile.tar.gz /home/techbrij
To untar tar file or uncompress tar.gz file
tar -xvf Myfile.tar
to list the content of tar.gz file.
tar -tvf Myfile.tar.gz
Network
ifconfig
show network information
iwconfig
show wireless information
ssh
To securely log onto remote systems
ssh remote_host
ssh remote_username@remote_host
ssh -p port_number remote_host
To start ssh agent and set environment variable
eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id_rsa
To copy files in secure way
scp source_file user@destination_host:destination_path
scp techbrij.txt [email protected]:/home/techbrij
if destination host access is already configured
scp techbrij.txt xxx.xxx.xxx.xxx:~/
to copy folder recursively
scp -r folder destination
scp -r /home/techbrij/ [email protected]:~/
Shortcuts
Paste in terminal
Shift+ Insert
To open terminal
Ctrl+ Alt + T
To switch apps
Alt + Tab
Switch between windows from the same application
Alt + `
Pop up command window
Alt+F2
Lock the screen
Ctrl + Alt + L
Others
clear
Clears the current screen
which <commandname>
To find the path of the application
which svn
which node
nautilus
To open file explorer
history
prints the history of executed commands in terminal
pwd
pwd = print working directory
md5sum
To verify integrity of files
md5sum myfilename.deb