Linux Commands Archive

A compiled list of linux commands that I’ll keep adding to. Includes a general list section, and then an explanation/example section. They aren’t in alphabetical order, so please use your browser’s search/find function!

Commands to add: uci show network

Command Line Shortcuts

Keyboard shortcuts can be used on the command line. Here is a table of common ones:

Linux Commands

• cd - changes directory
• cat - concatenate
• chmod - change file/directory permissions
• clear - clears the terminal screen
• cp - copy files or directories & content
• echo - displays a line of text
• find - search for files in a directory
• grep - find a word and print pattern matched lines
• history - lists history of commands
• hostname - returns system’s hostname
• ip - configure network interfaces
• ls - list files and directories
• man - manual page for commands
• mv - move and rename files and directories
• mkdir - create directories
• ping - checks whether network or server is reachable
• pwd - prints current working directory
• ssh - secure shell encrypted CLI connection to remote network devices
• su - switches user
• sudo - superuser do
• touch - create an empty file
• tail - display last 10 lines of a file
• wget - downloads files from internet using HTTP, HTTPS, and FTP protocols
• uname - prints detailed information about Linux system/hardware
• useradd - create a new account

Explanations & Examples

ls

ls lists files and directories in the current directory, or the specified directory. The command accepts flags. -R stands for recursive and will return all files in the subdirectories too, while -a will show hidden files that start with .. Basic syntax: ls [flags] [directory]

General shortcuts: / for root, .. for parent directory one level above, ../.. for two levels above, ~ for home directory.

Example:

ls -l
drwxr-xr-x. 1 calistahan calistahan 48 Oct 26 16:21 Documents

man

man is a built-in manual for commands in linux. The scroll wheel/mouse, up and down keys, and PgDn and PgUp keys can all be used to navigate through the manual. Q/q is pressed to exit. The basic syntax is simply man [command].

Man pages can include information such as the name, synopsis, configuration, description, examples, defaults, options, exit status, environment, files, authors, history, notes, bugs, etc.

Example:

man -f mkdir
mkdir (1)       - make directories
mkdir (2)       - create a directory

sudo

sudo stands for superuser do, and allows you to perform admin tasks or have root privileges for a command. The general syntax is sudo [command].

Example:

[calistahan@fedorahat ~]$ rmdir Documents
This command requires root privileges.
[calistahan@fedorahat ~]$ sudo !!

sudo !! is a helpful shortcut to repeat the previous command typed and entered but with sudo, so you don’t have to retype the whole command.

pwd

pwd prints the path of your current working directory. It can take the -L / --logical and -P / --physical options to print environment variable content (with symbolic links included) or the actual path of the current directory, respectively.

Example:

[calistahan@fedorahat ~]$ pwd
/home/calistahan

cd

cd changes the current directory. Running it by itself as cd will take the user to the home folder. If you wish to go to a child directory, simply the directory name will do. If you wish to go somewhere completely else, the command will need the full path.

Example:

cd /home/calistahan/Documents/schoolFiles

Shortcuts: cd .. will move one directory up. cd- will go to the previous directory.

cat

concatenate will write file content to standard output so you can read it easily. cat can also be used to create a new file and combine files. Use cat > filename to create a new file and cat filename filename2 > filename3 to store a merged file.

Example:

cat hello.txt
hello world!

cat > hello2.txt // creates a new file 
cat file1.txt file2.txt > combined.txt // merges file1.txt and file2.txt and stores as combined.txt

Use with command tac to display content in reverse order.

cp

cp can copy files and directories and directory content. Files can be copied to other files or other directories. The -R flag will copy the entire directory.

Basic syntax: cp [source] [destination]

Example:

cp tester.txt /home/calistahan/Documents/website/hello.txt

mv

mv can be used to move or rename files and directories.

Basic syntax: mv [source] [destination]

Example:

mv tester.txt /home/calistahan/Documents/testFiles
mv helloworld.txt HelloWorld.txt

mkdir

mkdir creates directories and can set permissions at the same time.

Basic syntax: mkdir [option] [directoryName]

Basic options: -m can set file permissions. -m777 will set full read, write, and execute permissions. -v will print a message when the directory is created. By default, no message is printed. -p / --parents will make a directory in between two folders.

Example: Create ‘rap’ directory inside music, create ‘test’ directory with full read/write/execute permissions, and create ‘songs’ directory between ‘music’ and ‘rap’.

mkdir /music/rap
mkdir -m777 test
mkdir -p /music/songs/rap

touch

touch can be used to create a new, empty file, and to also change file timestamps. Using it on an existing file will change the access and modification times to the current time, while using it on an argument that doesn’t exist will create an empty file.

Common flags: -a to change only the access time, -m to change only the modifiction time, -c to not create any files.

Example:

[calistahan@fedorahat ~]$ touch newFile.txt

find

grep

grep prints lines that matches patterns. It searches for a pattern in each file, and each line that matches will be printed.

Common flags: -i / --ignore-case will ignore case when searching for a pattern. On the flip side, --no-ignore-case will do the opposite - and is the default option. -v / --invert-match will invert the matching and print non-matching lines instead. -c / --count will print the number of matching lines instead.

ip

ip is used to configure network interfaces and more.

Options: link l display and modify network interfaces, address a display/modify IP addresses, route r display/alter routing table, etc. ip OBJECT help will display list of commands and arguments for each object.

ip addr show will list all network interfaces and each associated ip address. Similarly, ifconfig may be used instead.

ssh

ssh Secure Shell is a network administration tool that provides an encrypted command line remote connection.

Example:

ssh root@192.168.1.1

This command will initiate an SSH connection as the root user of 192.168.1.1

tail

chmod

ping

wget

uname

clear

history

echo

hostname

su

useradd