Beginners guide to Linux commands!!
What is Linux??
Linux is an operating system kernel. It is a UNIX clone. Linux is free and open source. Linux has many distributions known as “distros”.RHEL, Ubuntu, Debian are some of them.
What is Linux Shell or Terminal?
Linux shell takes commands from the user gives it to the operating system for processing and gives output.
Basic File commands:
ls displays the list of files and folders.
ls -a displays a list of files including the files starting with a .
ls -t displays files sorted by time, newest first
mkdir DirName used to create a new Directory
cd DirName used to change the current working directory to the specified directory.
cd .. used to Go up one directory
pwd print the current working directory.
touch filename.extension create a file
rm filename Delete a file
rm -r directoryName Delete directory
rm -f filename Force remove a file
head filename Output the first ten lines of a file
tail filename Output the last ten lines of a file
more filename Output the contents of the file
cp firstfilename secondfilename copies the content of first file to the second
System Info
date shows the current date and time
cal shows the month’s calendar
uptime shows the current uptime
whoami displays your username
finger user displays information about the user
uname -a shows kernel information
man command shows the manual for the command
df shows the disk usage
free shows memory and swap usage
whereis app shows possible locations of app
Network
ping host Ping host and output results
whois domain Gives information about the domain
dig domain get DNS information of the domain
dig -x host reverse lookup host
ifconfig configure a network interface
SSH
ssh user@host connect to the host as user
ssh -p port user@host connect to host on port
COMPRESSION
tar is a software for collecting many files into one archive file.The .tar extension is similar to .zip or .7z
tar cf file.tar files Create a tar named file.tar containing files
tar xf file.tar Extract the files from file.tar
VIM EDITOR
vim is the most widely used text editor in Linux
vi filename.extension to create a file and open it in the editor
Press the Insert key and then add text or edit the text in your file.
Press Esc key when done press: wq to save all changes and exit
:q! quit vim without saving changes
:w save the changes
:q to quit when no changes are made. Will fail to quit when some changes are made
INSTALLATION
Installing a package from source
./configure
make
make install
Install a Debian Package
dpkg -i pkg.deb
Install a package(RPM)
rpm -Uvh pkg.rpm
SHORTCUTS
1)ctrl-c stop current command
2)ctrl-z sleep program
3)ctrl-a Go to start of the line
4)ctrl-e Go to end of the line
5)ctrl-u Cut from the start of the line
6)ctrl-r Search history
7)!! Repeat the last command
8)!pqrs Run the last command starting with pqrs
9)!pqrs:p Print last command starting with pqrs
10)^pqr¹²³ Run the previous command replacing pqr with 123
