{dev_notes}

Bash Profile

Published 3 years ago.
Last updated

Bash is the shell, or CLI (Command Language Interpreter) for the Linux operating system. A shell defines the environment in which the user can execute programs, and accepts commands from the keyboard and executes them.

User Profiles

When you work with the command line frequently you will want to customize the environment. This can mean changing environment variables, such as where the shell looks for commands or how the prompt looks, or adding customized commands. Bash uses the user profile files .bash_profile and .bashrc to allow specific environment configurations to be defined for a user.

Profiles in MacOS

The usual convention in Linux is that the .bash_profile file is executed for login shells (username/password prompts, ssh to remote hosts, etc.) and the .bashrc file is used for non-login shells like Terminal. The basic idea being that the .bash_profile should only be run once at login, and the .bashrc for every new interactive shell. However, Mac does not follow this convention, but some applications which run on Mac do. The solution is to put all configuration code in .bashrc and include (source) .bashrc from within the .bash_profile file. More info below.

Another catch. With the release of Catalina, Apple has changed the default shell for macOS to zsh due to licensing concerns. It works the same but uses differently named configuration files in the same location. For instance .bashrc is now .zshrc and .bash_profile is .zprofile.

Profile Files

  • In Terminal change to your current users home directory:
cd ~/
  • List all files and directories, including hidden files with:
ls -la
  • Create the .bash_profile file:
touch .bash_profile
  • Use ls -la to list the files again to confirm the new .bash_profile file was created.
  • Open the .bash_profile file in a text editor (nano .bash_profile).
  • Add the following code to include the .bashrc file into the .bash_profile file:
[ -r ~/.bashrc ] && . ~/.bashrc
  • Save and close the file.
  • Run cat .bash_profile to print so you can verify the contents of the file.
  • Create the .bashrc file:
touch .bashrc

Now all new additions to the user profile can be added to the .bashrc file.

Profile Configurations

  • Open the .bashrc file in a text editor (nano ~/.bashrc).
  • Add configurations and then save and close the file.
  • Changes will appear the next time a new Terminal window is open.

Command Prompt

# Command prompt.
export PS1='\u@\h:\w$ '

$PATH

The PATH environment variable is a string of colon-separated (:) values. Each value is a path to a directory. The OS will check each directory, in the order they were defined, while searching for the executable file for a program.

MacOS sets the PATH environment variable to /usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin by default.

  • If you type echo $PATH into Terminal, and /usr/local/bin or ~/usr/bin is first, you are ready to go.
  • ~/usr/bin is equivalent to /usr/local/bin.

Eaxample

Add the folders my_directory and my_other_directory, from under the home directory to the PATH variable:

export PATH="$PATH:~/my_directory:~/my_other_directory"

Default text editor

Define the default console text editor in the EDITOR variable.

export EDITOR="/usr/bin/nano"

ls Alias

Alias the ls -la command for listing all directory content including hidden files.

alias l='ls -la'

Directory shortcut

Change to the Projects directory when you type cdp.

alias cdp='cd ~/Projects'

More Resources