Customizing your Terminal

• bashrc and bash_profile
• Modifying your prompt
• Aliases
• Environment variables
• Paths

You should customize your shell according to your needs!

bashrc and bash_profile

• bashrc: Initializes an interactive session
• bash_profile: Executed once when starting shell

But most of the settings go in bashrc file!

In Mac OSX, both files exist. In Linux, only one is used!

bashrc and bash_profile

A typical bashrc file looks like this:
https://gist.github.com/giggio/1704664

                        # ~/.bashrc: executed by bash(1) for non-login shells.
                        # see /usr/share/doc/bash/examples/startup-files (in the package bash-doc)
                        # for examples

                        # If not running interactively, don't do anything
                        case $- in
                            *i*) ;;
                              *) return;;
                        esac

                        # don't put duplicate lines or lines starting with space in the history.
                        # See bash(1) for more options
                        HISTCONTROL=ignoreboth

                        # append to the history file, don't overwrite it
                        shopt -s histappend

                        # for setting history length see HISTSIZE and HISTFILESIZE in bash(1)
                        HISTSIZE=1000
                        HISTFILESIZE=2000

                        # check the window size after each command and, if necessary,
                        # update the values of LINES and COLUMNS.
                        shopt -s checkwinsize

                        # If set, the pattern "**" used in a pathname expansion context will
                        # match all files and zero or more directories and subdirectories.
                        #shopt -s globstar

                        # make less more friendly for non-text input files, see lesspipe(1)
                        [ -x /usr/bin/lesspipe ] && eval "$(SHELL=/bin/sh lesspipe)"

                        # set variable identifying the chroot you work in (used in the prompt below)
                        if [ -z "${debian_chroot:-}" ] && [ -r /etc/debian_chroot ]; then
                            debian_chroot=$(cat /etc/debian_chroot)
                        fi

                        # set a fancy prompt (non-color, unless we know we "want" color)
                        case "$TERM" in
                            xterm-color) color_prompt=yes;;
                        esac

                        # uncomment for a colored prompt, if the terminal has the capability; turned
                        # off by default to not distract the user: the focus in a terminal window
                        # should be on the output of commands, not on the prompt
                        #force_color_prompt=yes

                        if [ -n "$force_color_prompt" ]; then
                            if [ -x /usr/bin/tput ] && tput setaf 1 >&/dev/null; then
                            # We have color support; assume it's compliant with Ecma-48
                            # (ISO/IEC-6429). (Lack of such support is extremely rare, and such
                            # a case would tend to support setf rather than setaf.)
                            color_prompt=yes
                            else
                            color_prompt=
                            fi
                        fi
                        

You can use these files to customize how your shell session behaves, as well adding new environment variables!

Setting up your SHELL session

Modifying your prompt

• Open the terminal and type: nano ~/.bashrc. (If it doesn't exist, create it with touch.)

                        parse_git_branch() {
                            git branch 2> /dev/null | sed -e '/^[^*]/d' -e 's/* \(.*\)/ (\1)/'
                        }

                        export PS1="\[\033[36m\]\u\[\033[m\]@\[\033[32m\]\h:\[\033[33;1m\]\w\[\033[m\]\$(parse_git_branch)\[\033[00m\] "
                        export CLICOLOR=1
                        export LSCOLORS=ExFxBxDxCxegedabagacad
                        alias ls='ls -GFh'
                        

• Hit Control+O to save, then Control+X to exit out of nano

Modifying your prompt

• This function extracts the current git branch.

                        parse_git_branch() {
                            git branch 2> /dev/null | sed -e '/^[^*]/d' -e 's/* \(.*\)/ (\1)/'
                        }
                        

Modifying your prompt

• Changes the bash prompt to be colorized, and rearranges the print to be username@hostname:cwd $(git-branch)

                        export PS1="\[\033[36m\]\u\[\033[m\]@\[\033[32m\]\h:\[\033[33;1m\]\w\[\033[m\]\$(parse_git_branch)\[\033[00m\] "
                        

Modifying your prompt

• The next two lines enable command line colors, and define colors for the 'ls' command

                        export CLICOLOR=1
                        export LSCOLORS=ExFxBxDxCxegedabagacad
                        

Modifying your prompt

• -G: Colorizes output
• -h: Makes sizes human readable
• -F: Throws a '/' after a directory, '*' after an executable, and a '@' after a symlink

                        alias ls='ls -GFh'
                        

Modifying your prompt

You can also modify the aspect of
your command prompt

                        username@hostname:/path/to/working/directory (git-status)
                        

You can add this to bashrc file!

Modifying your prompt

Under data >> day_03 >> dot_files

These are a set of sample dot files that you can add to your main directory.

Modifying your prompt

Or you can use

to also customize your prompt:

Aliases

• Keyboard shortcuts!
• For simple and complex commands
• Temporary or permanent
• Used to navigate your terminal
• etc.

Aliases

I like to save my aliases in
~/.aliases

                        ############################## --- GENERAL --- ################################
                        alias   lll='ls -lah'
                        alias   LLL=lll
                        alias   lla=lll
                        alias   llh='ls -lh'
                        alias   llt='ls -lahtr'
                        alias    LS='ls'
                        alias    sl='ls'
                        

... and many more

Creating aliases

Creating aliases

If you want a temporary alias, type

                        alias name_of_alias="command"
                        

For example:

                        alias ll="ls -al"
                        

Now whenever you type ll, the system will understand it as ls -la

Creating aliases

If you want a permanent alias, you need to modify your ~/.bashrc file

                        ## Example of other aliases
                        alias pushd='cd -'
                        alias    CD='cd'
                        alias tree='tree -C'
                        alias crone='crontab -e'
                        alias cronl='crontab -l'
                        alias     jb='jupyter notebook'
                        

This file is a compilation of useful aliases for your terminal!

(See the repository)

Removing aliases

If you want to remove an alias, type:

                        unalias command_name
                        

This will remove the alias from the current session!

For example:

                        # This will remove the 'crone' alias
                        unalias crone
                        

If you want remove a permanent alias, you will need to edit your ~/.aliases file!

Aliases

Whenever you modify your ~/.aliases file, you need to source it again:

                        source ~/.aliases
                        

This will update the aliases in your current session

Exercise

• Create a temporary alias for
  "ping www.google.com"
• Add the aliases from the .aliases file from the repository to your local version
• Go to https://tinyurl.com/bcb18-repo
• Make sure you're in the "master" branch
• Copy the aliases in the .aliases file to your .aliases file in $HOME directory.

Aliases

For more info on aliases and how to use them,
see:

Environment variables

Environment variables

• When the shell session starts, the system compiles info that should be available to the shell session.
• Key-value pairs
• Temporary or permanent

Typically, environment variables look like:

                        KEY="value with spaces"
                        

or

                        KEY=value1:value2:...
                        

Creating environment variables

Creating a variable named TEST_VAR

                        TEST_VAR='Hello World!'
                        

And you can access it by:

                        echo $TEST_VAR
                        

Now you need to export the variable

                        export TEST_VAR
                        

This will ensure that your variable TEST_VAR
is available!

Using environment variables

You can set environment variables in your current shell, or you can make them permanent

You can do this adding them to your ~/.bashrc file

                        ## .bashrc file
                        ...
                        # Defining environment variable TEST_VAR
                        TEST_VAR='Hello World!'
                        export TEST_VAR
                        ...
                        

and type this in the terminal

                        source ~/.bashrc
                        

This will source the new environment variables!

Environment Variables

For more information on environment variables,
see:

Putting it all together ...

You learned how to

• Customize the way your terminal prompt looks
• Edit your ~/.bashrc file
• Work with aliases
• Set environment variables

Now you can add/modify your environment. You can use the dot files found at:

(Note: Make sure you're in the master branch!)