Linux Cheat sheet
Tags: linux, devops, aws, cloud
Published: 2022-12-28 04:12:50

**Below we will see some of the important commands in Linux
System Based Commands**

- #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

**Hardware Based Command**

- #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)

**Users Management Commands**

- #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_

**File Commands**

- #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


**Process Related Commands**

- #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

**File Permission Commands**

- #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

**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 ports

**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_nameInstall package using dnf utility

What is DNF utility?
DNF - The Next Generation Package Management Utility for RPM Based Distributions
A recent news draw the attention of many Linux users, professionals and learners that " DNF" (stands for nothing…
www.tecmint.com

**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 +10000kFind 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-pointMount a device

**Directory Traverse Commands**

- #cd .. Move up one level in the directory tree structure
- #cd Change directory to $HOME directory
- #cd /test Change directory to /test directory

Thanks for reading✨
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_Rajani ✨