lab_2

Customising the shell – Readline

Main configuration files

There are several main files that are used to configure shell on a system:

• system-wide configuration files bash.bashrc (or simply bashrc) and profile, which can be found in /etc/ folder (on Windows it's located inside Git installation directory, such as C:\Program Files\Git\etc)
• user-specific dotfiles bashrc and .bash_profile or .profile, which are located in the user's home folder (they are covered in Lab 3).

Another file that affects user experience of working with command line is .inputrc (and its system-wide /etc/inputrc counterpart). This is the configuration file of Readline — a library which provides line-editing and history capabilities for many command-line utilities, including bash.

Some useful default Readline hotkeys

I really can't stress enough how useful these hotkeys are in the everyday work. Take some time to remember them.

• Tab – autocomplete
• Ctrl + l – clear the screen
• Ctrl + k – cut forwards to the end of the line
• Ctrl + u – cut backwards to the start of the line
• Alt + d – cut forwards to the end of the current word
• Alt + Delete / Ctrl + w – cut backwards to the start of the current word
• Ctrl + _ – incremental undo for editing commands
• Ctrl + y – paste the last deleted snippet (top of the kill ring)
• Ctrl + t – transpose characters
• Alt + t – transpose words
• Alt + u – uppercase the current word
• Alt + l – lowercase the current word
• Alt + c – capitalise the current word
• Alt + # – – comment the current line and start a new one

Tweaking .inputrc

Let's start with the single most important improvement that you can make to your command line experience — enabling incremental history search.

Create .inputrc file in your home directory:

touch ~/.inputrc

Add the following snippet to it:

# Up/down arrows to search history
"\e[A": history-search-backward
"\e[B": history-search-forward

After you reload the console you will be able to search history incrementally — that is, filtering the commands that you want to see by providing a few of the starting characters of those commands. This makes a huge difference to your productivity on command line, as repeating the commands that you use often now takes only several keystrokes. The longer you use console to interact with your system, the better bash history works for you.

You can also use Ctrl + ← / → and Alt + ← / → to skip words:

# Ctrl + left/right arrows to skip words
"\e[1;5C": forward-word
"\e[1;5D": backward-word

# Alt + left/right arrows to skip words
"\e\e[C": forward-word
"\e\e[D": backward-word

Ignore case in Tab-completions (on Windows this is the default):

set completion-ignore-case on

Add some colour to Tab-completions:

set colored-stats on

Make sure we don't output everything on 1 line:

set horizontal-scroll-mode Off

Show all possible matches immediately, without having to hit Tab twice:

set show-all-if-ambiguous on