Bash

Bash is a Unix shell and command language written by Brian Fox for the GNU Project as a free software replacement for the Bourne shell. First released in 1989, it has been distributed widely as the shell for the GNU operating system and as a default shell on Linux and OS X.

Tip

Think of Bash as a program that takes in commands and executes them. It is a command-line interpreter that allows you to interact with your computer using text commands, but it can also run scripts that automate tasks.

Basic Commands

List

Lists files in the current directory.

foo@bar:~$ ls

Some flags that can be used with ls:

• -l: long listing format
• -a: list all files, including hidden files
• -h: human-readable file sizes

ls can also take a directory as an argument to list files in that directory.

ls /path/to/directory

Print Working Directory

Prints the current working directory.

foo@bar:~$ pwd

Echo

Prints a message to the terminal.

foo@bar:~$ echo "Hello, World!"

Change Directory

Changes the current working directory.

foo@bar:~$ cd /path/to/directory

To move up one directory (the parent directory), use ...

foo@bar:~$ cd ..

To move to the home directory, use ~.

foo@bar:~$ cd ~

Make Directory

Creates a new directory.

foo@bar:~$ mkdir new_directory

Copy

Copies files or directories.

foo@bar:~$ cp file1 file2

Concatenate

Concatenates and displays the contents of files.

foo@bar:~$ cat file1 file2

Tip

Most of the time to display the contents of a file, you can use cat or less. cat is used to display the entire file at once, while less is used to display the file one page at a time.

Remove

Removes files or directories.

foo@bar:~$ rm file1

To remove a directory and its contents, use the -r flag (recursive).

foo@bar:~$ rm -r directory

Tip

Typically, this is appended with the -f flag to force the removal of files without prompting for confirmation.

Connections

• Topic index

Obvious technical and formatting errors repaired.