linux commands cheatsheet

#linux #productivity #tooling #beginners

Unix was published in 1973. Since them there where many different operating systems build using the same standards as Unix. The most prominent are Linux and MacOS. More than 90% of cloud infrastructure and more than 80% of smartphones in the world are based on Linux.
If you want to see whats going on an EC2 instance or filter some log files you can always use the command line tools.

Using the command line tools for administrative work or lookups will save a lot of time and increase the productivity significantly compared to using only graphical interfaces.

As a webdeveloper we use the following commands on a daily basis. If you are new to this topic, I hope this will help you increase productivity.

Orientation

command	explanation
history	displays the history of the last used commands
pwd	print working directory
man [command]	manual
echo	echoes an argument

Navigating in the terminal

When we keep our hands on the keyboard we are always faster, than when use the mouse or similar to navigate around. So we should make use of the following commands, when we are in a terminal.

ctrl + a: jump to the beginning of a line
ctrl + e: jump to the end of a line
ctrl + w: remove word
ctrl + u: remove whole line
option + left arrow: jump to the end of a word
option + right arrow: jump to the beginning of a word
tab: autocompletion
arrow up: show last used command
cmd + k: clear terminal screen

Navigating in the file system

command	explanation
ls	list - lists all files in the current directory
ls -a	lists all but also shows the .hidden files
ls -la	lists all files in the long file format
cd /	navigate to the root directory
cd ~	navigate to the home directory
cd ..	navigate one directory level up
cd -	navigate to the previous directory

Administrative tasks

command	explanation
sudo	superuser do
mkdir [directory_name]	make directory
rmdir	removes a directory
touch [file_name]	creates a file
cp old_file_name new_file_name	copy
mv old_file_name new_file_name	move
rm [file_name]	remove
rm -r	removes recursive, ie a Folder with all contents
vi [file_name]	opens file with vi
nano [file_name]	opens file with nano
code [file_name]	opens file with vs code
program_name	to start a program simply type the name, ie python
ctrl + c	stop a program

Searching and filtering

command	explanation
head [file_name]	show the first 10 lines of a file
tail [file_name]	show the las 10 lines of a file
sort [file_name]	sorts the file alphabetically
sort [unsorted_file_name] > [sorted_file_name]	sorts the content of the unsorted file and stores it in a new sorted file
cat [options] [file_names]	reads files sequentially, writing them to standard output
grep [options] pattern [file_names]	globally search for regular expression and print
the pipe	The pipe send the output of one command as input of another command.

As grep, cat and | are powerful tools I recommend having a look at this awesome tutorial.

Permissions

In Unix Systems there are three groups of ownership.

USER: the one who created the file
GROUP: a group with assigned users
OTHER: any other who has not created the file and does not belong to a group.

The UNIX system has 3 permissions defined for the 3 different owner groups:

r = read permission
w = write permission
x = execute permission

– = no permission
d = directory
@ = extended attributes on macOS

Changing permissions

command	explanation
chmod	change mode
chown	change owner

Detailed information for the permission system can be found here.

This post is outlining the most important commands (for me). If you want to see all commands you might want to have a look at this list or use the man in the terminal.