Linux Commands Reference Guide

Vocabulary flashcards covering core Linux commands for file system navigation, file reading, file management, content filtering, user/permission management, and Linux help utilities.

cd

Navigates between directories.

ls

Displays the names of the files and directories in the current working directory.

ls -a

Displays hidden files when displaying the names of files and directories inside the current working directory.

ls -l

Displays permissions to files and directories in the current working directory; also displays additional information, including owner name, group, file size, and time of last modification.

ls -la

Displays permissions to files and directories in the current working directory, including hidden files, along with owner name, group, file size, and time of last modification.

pwd

Prints the working directory to the screen.

whoami

Returns the username of the current user.

cat

Displays the content of a file.

head

Displays just the beginning of a file, by default 10 lines.

less

Returns the content of a file one page at a time and changes the terminal window to allow moving forward and backward through content.

tail

Displays just the end of a file, by default 10 lines.

cp

Copies a file or directory into a new location without removing the file from its previous location.

mkdir

Creates a new directory.

mv

Moves a file or directory to a new location, removing it from the previous location, or renames a file.

nano

Opens or creates a file in the nano command-line file editor.

rm

Removes, or deletes, a file.

rmdir

Removes, or deletes, a directory; only removes directories if they are empty.

touch

Creates a new file.

find

Searches for directories and files that meet specified criteria.

grep

Searches a specified file and returns all lines in the file containing a specified string.

Pipe (|)

Sends the standard output of one command as standard input to another command for further processing.

chmod

Changes permissions on files and directories.

chown

Changes ownership of a file or directory; used with sudo.

groupdel

Deletes a group from the system; used with sudo.

sudo

Temporarily grants elevated permissions to specific users; users must be listed in a sudoers file to have access.

useradd

Adds a user to the system; used with sudo.

userdel

Deletes a user from the system; used with sudo.

userdel -r

Deletes a user and deletes all files in their home directory.

usermod

Modifies existing user accounts; used with sudo.

apropos

Searches the manual page descriptions for a specified string.

man

Displays information on other commands and how they work; output is called a man page (short for manual page).

whatis

Displays a description of a command on a single line.