Bash on Raveen Kumar

fc fix command or fix previous command

Fri, 12 May 2023 00:00:00 +0000

In Bash, fc stands for “fix command” and it is a built-in command that allows you to work with the command history. The fc command provides a way to view, edit, and re-execute commands from your command history.

Here are some common uses of the fc command:

Viewing command history: You can use fc -l or simply fc to display the list of recently executed commands. By default, it shows the most recent commands with line numbers.

Bash

Thu, 16 Feb 2023 00:00:00 +0000

Bash

Reading materials

Select statement

select opt in y n; do
	echo $opt
done

This creates a loop where the user can select the option. Use case to break out of the loop.

select opt in y n; do
	echo $opt selected
	case $opt in
		y)
			break 
			;;
		n)
			break 
			;;
		*)
			echo wrong option
			;;
	esac
done

Bash variables

$USER
$HOSTNAME
$PS1

To Find or List all environment variables

env

This is useful when we want to manage the shell variables properly

How to customize tmux status bar with shell scripts

Thu, 06 Oct 2022 00:00:00 +0000

TMUX status bar can be customized to run shell scripts.

In the .tmux.conf file, in the status left or right command execute the shell script using the following syntax,

set -g status-right '| #(shell_script.bash) |'

This will print the output of that shell script in the status bar. Useful if you want to check the size the home directory.

Contents of shell_script.bash example

#!/bin/bash

df -h $HOME | awk '{print $5}' | tail -n 1

How to change hostname

Tue, 13 Sep 2022 00:00:00 +0000

How to change hostname

Print hostname

hostname
hostname -I
echo $HOSTNAME

To change hostname

sudo hostname -b <New name>
sudo echo <new name> /etc/hostname

change name in /etc/hosts
If you are in wsl, add the following entry to /etc/wsl.conf

[network]
generateHosts = false

Restart computer

How to kill subprocess of a shell

Tue, 08 Feb 2022 00:00:00 +0000

How to kill subprocesses of a shell

In bash $$ will get you current process id.

You can use pkill -P $$ to kill all subprocess of the current shell.

   -P, --parent ppid,...
          Only match processes whose parent process ID is listed.

Stackoverflow answer