Most useful linux command – ls, cd, cp, mv, rmdir, rm, ifconfig, ping, netstat, traceroute, pidof, kill, df

Hello  friends, Here u can find the most useful & frequently required Commands on Linux terminal . This post is basically for those who just started operating  Linux OS.  These commands are executed on Ubuntu 16.04 OS. To learn these commands, open terminal by pressing keys CTRL + ALT + T simultaneously.

ls command

ls with no option shows the list files and directories in bare format of current directory. It won’t shows details like file types, size, modified date and time, permission and links etc.

To display file and directories


To display hidden files

ls -a

To display all files and directories with size

ls -lh

To display Recursively list of Sub-Directories

ls -R

To Sort Files by File Size

ls -ls

To shows latest modification file or directory date as last.

ls -ltr

mkdir command

mkdir is used to create directories on a file system.

Syntax : 
mkdir directory_name

Example : 
mkdir tutorials

cd command

It allows you to change your working directory. You use it to move around within the hierarchy of your file system. The double-dot (“..”) directory notation can be used anywhere in a directory name to represent going up one level.

Syntax :
cd directory_path

Example :
cd /home/user_name/documents
cd ..

cd .. commands moves to its parent directory as /home/username

mv command

The mv command is used to move or rename files. mv renames file SOURCE to DEST, or moves the SOURCE file (or files) to DIRECTORY.

Syntax :
mv filename destination-directory

Examples :
mv file.txt /home<br>

cp command

The cp command is used to make copies of files and directories.

Syntax :
cp origfile /directory/subdirectory

Example :

Copy multiple files into another directory, using a wildcard:
cp file*.jpg /directory/subdirectory

Copy an entire directory structure into another location:
cp -R /one/two /three/four

You can use cp to copy entire directory structures from one place to another using the -R option to perform a recursive copy.

rmdir command

The rmdir utility removes the directory entry specified by each directory argument, provided the directory is empty.

rmdir directory_name

rmdir tutorials

rm command

rm command is used to delete files from a file system. Usually, on most file systems, deleting a file requires write permission on the parent directory and execute permission.

Syntax :
rm file1 file2 file3

Example :
To remove single or multiple files
rm abc.txt pqr.txt xyz.txt

To remove all files & subdirectories from a directory (u can delete non empty directory)
rm -rf mydir

-f: Forcefully remove file
-r: Remove the contents of directories recursively

ifconfig command

ifconfig is used to configure, or view the configuration of, a network interface. ifconfig stands for “interface configuration”. It is used to view and change the configuration of the network interfaces on your system. It will display information about all network interfaces currently in operation.

To activate eth1
sudo ifconfig eth1 up
To deactivate eth1
sudo ifconfig eth1 down

ping command

ping(Packet INternet Groper) is a simple way to send network data to, and receive network data from, another computer on a network. It is frequently used to test, at the most basic level, whether another system is reachable over a network, and if so, how much time it takes for that data to be exchanged. It is the best way to test connectivity between two nodes.


Netstat command:

It stands Network Statistic (Netstat) command to display connection info, routing table information, Tcp, Udp port, protocols information.

To displays routing table information
netstat -r

To display TCP Ports connections
netstat -at

To display UDP Ports connections
netstat -au

To display Statistics by Protocol
netstat -s

To get netstat information continuously
netstat -c

pidof command

Pidof finds the process id’s of the named programs. It prints that id’s on the standard output.

Example :
To find process id of running process 
pidof process_name 
pidof gedit
it return process id of running instance of gedit program. i.e process

Kill Command

kill is used to send a signal to a process. The default signal for kill is TERM (which will terminate the process). To test this command, just open gedit editor.

Syntax :
kill processid

Example :

pidof gedit

if it return process id as 9378, pass it as parameter to kill command.

kill 9378

traceroute Command

traceroute is a network troubleshooting utility which shows number of hops taken to reach destination also determine packets traveling path. Traceroute is a utility that records the route through the Internet between your computer and a specified destination computer. It also calculates and displays the amount of time each hop took.

Example: traceroute

df Command

The df command reports the amount of used and available disk space on file systems.

Example :
To display size in human readable form as KB,MB,GB..
df -h

To grand total of used , available size of all disks on file system.
df -total

all above are the most useful Linux commands for beginners with required options. if u want more options of these commands , just write command name and option –help, as show in example below.

Example :
df --help