⌨️Linux Commands

Description	Comands
System Info	uname -acat /etc/*-release
Update software -y assumes yes to all prompts	sudo apt-get update -y
Install software (Debian/Ubuntu) -y assumes yes to all prompts	sudo apt-get install -y <PACKAGE_NAME>
Uninstall software	sudo apt-get --purge remove <PACKAGE_NAME>
Show current file path	pwd
Show all files in current directory -l display as a list -a show hidden files -F show all directories with a / at the end, making them easier to see -h show directory sizes in human readable format -R list directories recursively -t sort by modification date in ascending order, means the higher will be come first -S sort by size -i displays Inode information -o shows owner of the files and directories but not the groups *<STRING_TO_MATCH>* used to only display files and directories matching the string This doesn't see to work correctly when used with -a	ls -l ls -l *<STRING_TO_MATCH>*
Show hidden files	ls -la
Create hard and soft links to files -s creates soft link	ln <FILE1> <FILE2> ln -s <FILE1> <FILE2>
Tree view of directories -d only show directories	tree tree -d /
Create, update the access, change, and modify times of files -t allows you to set the date and timestamp of the file to a specific value e.g. 12091600	touch touch -t <DATE> <FILENAME>
Create and remove directories -rf Forcefully remove a directory that contains files recursively	mkdir <NEW_DIRECTORY> rmdir <DIRECTORY_TO_DELETE>
Moving or Renaming a file Simply rename a file Move a file to another location, while possibly changing its name at the same time.	mv
Removing a file -f forcefully remove a file -r interactively remove a file (ask before removing)	rm
Viewing files (or combine files) that are not very long It does not provide any scroll-back. View backwards, starting at the last line with tac -n shows line numbers	cat tac
chmod builder	https://chmodcommand.com/
Restrict file so only owner can read -R to recursively change permissions for all folders and files below	chmod 440 <FILE/FOLDER> chmod -R 400 <FILE/FOLDER>
Make file executable	chmod u+x <FILE>
Count words in a file Default: lines, words, characters/bytes? -l Print the number of lines. -w Print the number of words. -m Print the number of characters. -c Print the number of bytes. -L Print the length of the longest line	wc
View larger files with a paging program It pauses at each screen full of text, provides scroll-back capabilities, and lets you search and navigate within the file. Use spacebar to paginate Use / to search for a pattern in the forward direction and ? for a pattern in the backward direction. An older program named more is still used, but has fewer capabilities: "less is more". -N shows line numbers	less
Show the first few lines of a file Same modifiers as tails	head
Shows the last few lines of a file Print the last 10 lines of a file by default Change the number of lines by doing -n 15 or just -15 if you wanted to look at the last 15 lines instead of the default.	tail tail 15 tail -n 15
Used to view documentation	man
Find where a program resides on the filesystem If a program isn't found with which then try whereis as it looks at a broader range of locations	which <PROGRAM_NAME>
Show home directory path for current user	echo $HOME
Change directory cd ~ or just cd changes to Home directory cd .. changes to parent directory (..) cd - changes to previous directory (- (minus))	cd cd ~ cd .. cd -
Move to a new directory but save the current directory for quick return pushd moves you to the directory specified in the argument popd returns you to the most recent directory from the last pushd command (so similar to cd - but saves it, even if you go to multiple cd commands between) dirs displays the current list of all directories saved with pushd	pushd <NEW_DIRECTORY> popd dirs
Find a file that contains specific text -r or -R is recursive -n is line number -w stands for match the whole word -l (lower-case L) can be added to just give the file name of matching files -e is the pattern used during the search	grep -rnw '<PATH>/<TO>/<SOMEWHERE>' -e '<TEXT>'
Count number of files in this directory and all sub-directories . look in current directory -name looks for files with the following name -iname ignores case of the name -type restrict the results to files of a certain specified type d for directory l for symbolic link f for a regular file * wildcard matches any string of characters ? wildcard matches any single character -ls shows additional information about files found -maxdepth limits results to a max depth specified -size looks for files with specified size	find find . -name "<FILE/DIRECTORY_NAME>" find . -name "test*" -ls find . -type f -name "test*" -ls find . -type d -maxdepth 1 find . -size 0
Search all files and directories on the sys Uses a local DB to index all files, so it can be faster than find but also out of date (updates once per day) DB can be manually updated using sudo updatedb	locate
Search for a specific package	sudo dpkg --list | grep <PACKAGE_NAME>
Total disk space used (disk usage) by current directory and all sub-directories -h shows sizes in human readable format -s summarize at the current depth Shows size of all folders (and everything they contain) and files at the selected location -a the all flag lists the sizes of all files and directories in the given file path. This option is often combined with the -h flag for ease of use. Notice the individual file sizes are listed with the directories. -c Shows the total of all disk usage for the given file path as a new line at the bottom * use for current location Useful notes on arguments: https://www.redhat.com/sysadmin/du-command-options	du -sh <LOCATION> du -sh <LOCATION>/* du -sh * du -shc *
Shows size of directories -T shows type of directory -h shows sizes in human readable format	df -Th
See if a service is running	service <service-name> status service --status-all
Search terminal history Keep pressing to search through previous commands that match	ctrl-r
Shows running processes and Env Args I think the ww does line wrapping	ps -auxww
Unrar unrars to the directory you are currently in	sudo unrar x <FILENAME>.rar
Run last command So to run the last command as sudo if you forget to add it to the start: sudo !!	!!
Open a file using sudo in a GUI application on Mac	sudo open -a <APPLICATION_NAME> /file/to/open
Show IP	ifconfig
Run command as a different user: sudo = be root so I can do anything.   su means "now be another user” When you run su as root, you don't need to provide the users' password So "sudo su" means "run command as other user, and only have to enter root password" Command to run = -c	sudo su postgres -c "psql"
How to Kill Processes https://www.cyberciti.biz/faq/kill-process-in-linux-or-terminate-a-process-in-unix-or-linux-systems/ -15: the default way to kill a process -9: Last resort way to kill a process	sudo kill -15 <PID>
Terminal command history -c delete current session history	history history -c
Delete all terminal command history	sudo rm ~/.bash_history
Diff	diff -arq /Diretory1 /Directory2
Find a file by name	sudo find / -type f -name “pg_hba.conf"
Find a directory by name	find / -type d -name "post*"
Change user Leave empty to change to root user	su
On a clean install, grant current user sudo powers	su <ENTER ROOT PASSWORD> echo "<USERNAME> ALL=(ALL) ALL" > /etc/sudoers.d/<USERNAME> chmod 440 /etc/sudoers.d/<USERNAME>
Shutdown / restart Requires sudo -h apparently this isn't actually needed -r restarts instead of shutting down now shuts it down immediately otherwise it will default to a 60 second delay All arguments	sudo shutdown -r now sudo shutdown -h 10:00 "Shutting down for scheduled maintenance."
Use a shell command in-line	ls -l $(dpkg --listfiles ftp)
Open an image from the command line	eog <IMAGE_FILE>
Alias a command persistently directly from the command line and reload terminal This is faster than opening the ~/.bashrc file manually and adding the line directly source ~/.bashrc reloads the new parameters into the current terminal session	echo "alias ls='ls -la'" >> ~/.bashrc source ~/.bashrc
Check public facing ip	curl https://ipinfo.io/ip
Show interface configuration	ifconfig
Kernel IP routing table	netstat -rn
List all ip routing tables	ip route show table all | grep -Po 'table \K[^\s]+' | sort -u
Show content of ip routing table	ip route list table <TABLE_NAME>
Delete ip routing table	sudo ip route flush table <TABLE_NAME>
Disable and uninstall SSH	sudo systemctl stop ssh sudo apt-get --purge remove ssh
rsync large files and directories -P show progress -a archive (good for large files or unstable connections) Keeps a record of both sides of transfer to make sure it is successful even if it drops out temporarily in the middle -v verbose -e specify remote shell to use	sudo rsync -Pav -e "ssh -i $HOME/Keys/<SSH_KEYS>.pem" <SOURCE_LOCATION> <DEST_USER>@<DEST_IP>:<DEST_LOCATION> sudo rsync -Pav -e "ssh -i $HOME/keys/Dev-Validator-Keys.pem" ~/TestDir [email protected]:~/
Find all files changed in the last 5 minutes starting at the / root directory to a maxdepth of 10 not including the paths /pro/* and /sys*/ Show updated time next to each file and folder	sudo find / -maxdepth 10 -not -path "/proc/*" -and -not -path "/sys/*" -mmin -5 -printf "%p %TY-%Tm-%Td %TH:%TM \n"
Change username -l flag to specify new name	usermod -l <NEW_NAME> <OLD_NAME>
Change groupname -n flag to specify new name	groupmod -n <NEW_NAME> <OLD_NAME>
UFW - Show all rules even when UFW is disabled	sudo ufw show added
Compress tar.gz	tar -czvf archive.tar.gz stuff
Extract tar.gz	tar -xzvf archive.tar.gz
Compress tar.xz	tar -cJf archive.tar.xz stuff
Extract tar.xz	tar -xvf archive.tar.xz
Show all available kernels	dpkg --list | grep linux-image
Show current kernel	uname -r
Remove kernel version	sudo apt remove -y linux-image-