#uname Displays Linux system information
#uname -rDisplays kernel release information
#uptimeDisplays how long the system has been running
#hostnameShows the system hostname
#hostname -iDisplays the IP address of the system
#last rebootShows system reboot history
#dateDisplays current system date and time
#whoamiDisplays who you are logged in as
#finger usernameDisplays information about the user
#lshw Displays information about system’s hardware configuration
#lsblkDisplays block devices related information
#free -mDisplays free and used memory in the system (-m indicates memory in MB)
#idDisplays the details of the active user e.g. uid, gid, and groups
#lastShows the last logins in the system
#whoShows who is logged in to the system
#groupadd "pink"Adds the group ‘pink’
#adduser "rajni"Adds user ‘rajni’
#userdel "rajni"Deletes user ‘rajni’
#usermodUsed for modifying user information
#ls -alLists files – both regular & hidden files and their permissions
#pwdDisplays the present working directory path
mkdir 'pink'Creates a new directory named ‘pink’
#rm file_nameRemoves a file
#rm -f filenameForcefully removes a file
#rm -r directory_nameRemoves a directory recursively
#rm -rf directory_nameRemoves a directory forcefully and recursively
#cp file1 file2Copies the contents of file1 to file2
#cp -r dir1 dir2Recursively 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_nameCreates a symbolic link to file_name
#touch file_nameCreates a new file
#cat > file_namePlaces standard input into a file
#more file_nameOutputs the contents of a file
#head file_nameDisplays the first 10 lines of a file
#tail file_nameDisplays the last 10 lines of a file
#gpg -c file_nameEncrypts a file
#gpg file_name.gpgDecrypts a file
#wcPrints the number of bytes, words and lines in a file
#xargsExecutes commands from standard input
#psDisplay currently active processes
#ps aux | grep 'telnet'Searches for the id of the process ‘telnet’
#pmapDisplays memory map of processes
#top Displays all running processes
#kill pidTerminates process with a given pid
#killall procKills / Terminates all processes named proc
#pkill process-nameSends a signal to a process with its name
#bgResumes suspended jobs in the background
#fgBrings suspended jobs to the foreground
#lsofLists files that are open by processes
chmod octal filename Change file permissions of the file to octal
Example
#chmod 777 peep.txtSet 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
#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 ports
#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
#rpm -i pkg_name.rpm Install an rpm package
#rpm -e pkg_name Removes an rpm package
#dnf install pkg_nameInstall package using dnf utility
#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 +10000kFind files greater than 10000k in the home folder
#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
#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-pointMount a device
#cd .. Move up one level in the directory tree structure
#cd Change directory to $HOME directory
#cd /test Change directory to /test directory
