Linux Cheat Sheet

Here is a great list of commonly used Linux commands to help you.

If like me you have a million things going through your head, cheat sheets can be an amazing bible to have to reference.

Take a look at this collection of commands.

File Commands

• ls -al Lists files – both regular &  hidden files and their permissions as well.
• pwd Displays the current directory file path
• mkdir ‘directory_name’ Creates a new directory
• 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 file2 Renames 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 file_name Displays the last 10 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

File Permission

• chmod octal filename Change file permissions of the file to octal
• chmod 777 /data/test.c Set rwx permissions to owner, group and everyone (everyone else who has access to the server)
• chmod 755 /data/test.c Set rwx to the owner and r_x to group and everyone
• chmod 766 /data/test.c 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

System

• uname  Displays  Linux system information
• uname -r Displays  kernel release information
• uptime Displays how long the system has been running including load average
• hostname Shows the system hostname
• hostname -i Displays the IP address of the system
• last reboot Shows system reboot history
• date Displays current system date and time
• timedatectl Query and change the System clock
• cal Displays the current calendar month and day
• w Displays currently  logged in users in the system
• whoami Displays who you are logged in as
• finger username Displays information about the user

Search

• 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

Network

• ip addr show Displays IP addresses and all the network interfaces
• ip address add 192.168.0.1/24 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 / PC
• whois domain Retrieves more information about a domain name
• dig domain Retrieves DNS information about the domain
• dig -x host Performs reverse lookup on a 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

Process Related

• 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 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
• fg n job n to the foreground
• lsof Lists files that are open by processes
• renice 19 PID makes a process run with very low priority
• pgrep firefox find Firefox process ID
• pstree visualizing processes in tree model

For some more great examples check out https://linoxide.com/linux-command/linux-commands-cheat-sheet/

Here is a tutorial for Linux administration, it is 2 hours long but it starts from the beginning and by the end you will be comfortable administering a Linux operating system.

Drop us a message or give us a call