Bash

Calculate offset seconds using bash.

Check known host fingerprint using bash function.

Detect if a command produces standard output.

Ensure that shell script exits on HTTP query failure.

Handle spaces in filenames within shell script.

In the past, I was using the date command to get the current datetime, but this is no longer the case.

Reuse the last argument of the previous command.

Alter and restore Bash shell options.

Temporarily disable bash history to perform more sensitive tasks inside interactive shell.

Use BASH here documents whenever you need a multi-line text inside redirection.

Use templates inside shell scripts by substituting environment variables.

Today, I will show you my personal shell prompt, so you could define your own custom bash prompt.

Create custom Bourne Again SHell package to disable network redirections and enhance system security.

Find out whether remote port is open using Bourne Again SHell network redirections.

Keeping SSH authentication agent in sync across multiple servers and terminal multiplexers is not an easy task, but can be solved by using consistent socket names used to connect to the SSH authentication agent.

Parse INI configuration file using Bash shell-script.

Store runtime configuration within shell script using a simple but effective method.

I have already described how to inspect a pipeline, but today I will show you how to write a shell script that will help you reconstruct a whole pipeline when all you got is a process ID that is part of the pipeline.

A pipeline is a sequence of multiple commands separated by the control operators. It is easy to understand as long as you see the whole picture, but I will show you how to inspect it when you have a single process ID.

Use bash redirection and process substitution to programmatically distinguish standard error from regular output.

Send output to multiple commands using tee utility and bash process substitution.

Write a simple Bash shell script that will allow you to specify the same option multiple times or provide multiple arguments to a single option.

Sometimes it is very convenient to define shell function and execute it remotely.

Sometimes it is important to monitor log file modification time to restart the writing process when the file was not modified for defined period of time. I have already described how to check file metadata using stat utility which can be used to solve this task, but today I want to take advantage of the plain ls command.

It is nothing fancy, but there are situations where it is beneficial to know how to identify and inspect command before execution.

I want to automatically log out the user from the login shell after a defined period of inactivity but leave X Window Terminals untouched. This will allow me to enhance security slightly, as I will not accidentally leave the superuser session running for a long time.

I often want to save a recently executed command to the personal log file for further reference, so let’s do it.

I have already written a blog post about useful Bourne Again SHell key sequences, so today, I will touch on another important aspect of the daily routine – the history.

The default interactive shell in Debian is Bourne Again SHell, so it is worth to invest some time to at least skim through the available readline key sequences to gain higher proficiency at the command-line.