Here are some important linux commands you must know !

💠 System/OS related commands.

#uname -Displays Linux system information

#uname -r -Displays kernel release information

#uptime -Displays how long the system has been running

#hostname -Shows the system hostname

#hostname -iDisplays the IP address of the system

#last reboot -Shows system reboot history

#date -Displays current system date and time

#whoami -Displays who you are logged in as

#finger username -Displays information about the user

💠 Hardware Based Command

#lshw -Displays information about system’s hardware configuration

#lsblk -Displays block devices related information

#free -m -Displays free and used memory in the system (-m indicates memory in MB)

💠 Users Management Commands

#id -Displays the details of the active user e.g. uid, gid, and groups

#last -Shows the last logins in the system

#who -Shows who is logged in to the system

#groupadd “dev” -Adds the group ‘dev’

#adduser - “dipraj”Adds user ‘dipraj’

#userdel - “dipraj”Deletes user ‘dipraj’

#usermod -Used for modifying user information

💠 File Commands

#ls -al -Lists files — both regular & hidden files and their permissions

#pwd -Displays the present working directory path

#mkdir - ‘test’Creates a new directory named ‘test’

#rm file_name -Removes a file

#rm -f filename -Forcefully removes a file

#rm -r directory_name -Removes a directory recursively

#rm -rf directory_name -Removes a directory forcefully and recursively

#cp file1 file2 -Copies the contents of file1 to file2

#cp -r dir1 dir2 -Recursively Copies dir1 to dir2. dir2 is created if it does not exist

#mv - file1 file2Renames file1 to file2

#ln -s /path/to/file_name link_name -Creates a symbolic link to file_name

#touch file_name -Creates a new file

#cat > file_name -Places standard input into a file

#more file_name -Outputs the contents of a file

#head file_name -Displays the first 10 lines of a file

#tail -20 file_name -Displays the last 20 lines of a file

#gpg -c file_name -Encrypts a file

#gpg file_name.gpg -Decrypts a file

#wc -Prints the number of bytes, words and lines in a file

#xargs -Executes commands from standard input

💠 Process Related Commands

#ps -Display currently active processes

#ps aux | grep ‘telnet’ -Searches for the id of the process ‘telnet’

#pmap -Displays memory map of processes

#top - Displays all running processes

#kill pid no -Terminates process with a given pid

#killall proc -Kills / Terminates all processes named proc

#pkill process-name -Sends a signal to a process with its name

#bg -Resumes suspended jobs in the background

#fg -Brings suspended jobs to the foreground

#lsof -Lists files that are open by processes

💠 File Permission Commands

chmod octal filename -Change file permissions of the file to octal

Example -

#chmod 777 peep.txt - Set rwx permissions to owner, group and everyone

#chmod 755 peep.txt -Set rwx to the owner and r_x to group and everyone

#chmod 766 peep.txt - Sets rwx for owner, rw for group and everyone

#chown owner user-file -Change ownership of the file

#chown owner-user:owner-group file_name -Change owner and group owner of the file

#chown owner-user:owner-group directory -Change owner and group owner of the directory

File permission — DevOps

💠 Network Commands

#ip addr show - Displays IP addresses and all the network interfaces

#ip address add 192.160.0.1/24 dev eth0 -Assigns IP address 192.168.0.1 to interface eth0

#ifconfig -Displays IP addresses of all network interfaces

#ping host -Ping command sends an ICMP echo request to establish a connection to server

#whois domain -Retrieves more information about a domain name

#dig domain -Retrieves DNS information about the domain

#host google.com - Performs an IP lookup for the domain name

#hostname -i Displays local IP address

#wget file_name -Downloads a file from an online source

#netstat -pnltu -Displays all active listening port

💠 Compression/Archives Commands

#tar -cf peep.tar peep<:code> -Creates archive file called ‘peep.tar’ from file ‘peep’

#tar -xf peep.tar -Extract archive file ‘peep.tar’

#tar -zcvf peep.tar.gz source-folder -Creates gzipped tar archive file from the source folder

#gzip file -Compression a file with .gz extension

💠 Install Packages Commands

#rpm -i pkg_name.rpm - Install an rpm package

#rpm -e pkg_name -Removes an rpm package

#dnf install pkg_name -Install package using dnf utility

💠 Search Commands

#grep ‘pattern’ files -Search for a given pattern in files

#grep -r pattern dir -Search recursively for a pattern in a given directory

#locate file -Find all instances of the file

#find /home/ -name “index” -Find file names that begin with ‘index’ in /home folder

#find /home -size +10000k -Find files greater than 10000k in the home folder

💠 File Transfer Commands

#scp file1.txt server2/tmp -Securely copy file1.txt to server2 in /tmp directory

#rsync -a /home/apps /backup/ -Synchronize contents in /home/apps directory with /backup directory

💠 Disk Usage Commands

#df -h -Displays free space on mounted systems

#df -i -Displays free inodes on filesystems

#fdisk -l -Shows disk partitions, sizes, and types

#du -sh -Displays disk usage in the current directory in a human-readable format

#findmnt -Displays target mount point for all filesystems

#mount device-path mount-point -Mount a device

💠 Directory Traverse Commands

#cd .. Move up one level in the directory tree structure

#cd Change directory to $HOME directory

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-Dipraj ✨