Learn Difference Between Sourcing and Forking in Bash
The main focus of this article is to clearly understand what happens when you run the script vs source the script in bash. First, we will clearly understand how the …
Learn Difference Between $$ and $BASHPID in Bash
Recently I was working on a shell script and I saw a significant difference in how bash special variable $ and BASHPID behaves. Every process running in Linux will be …
How to check if bash variable defined in script
I need to set a bash environment variable called PURGEIMAGE and take specific actions in my script. For example, if PURGEIMAGE set, then purge images from CDN else just URL. …
How to force awk not to print a newline
I have two columns (fields) in my text file. I am trying to insert ‘|‘ between two and create an HTML table based upon the updated file. My sample input …
How to install ShellCheck on FreeBSD to analysis scripts
ShellCheck is easy to use, free, and open-source static analysis tool that automatically finds bugs in your shell scripts. If you write shell scripts for automation or containers, you need …
How to declare Boolean variables in bash and use them in a shell script
I need to define a bash variable called failed and set the value to False. When my script is called from a cron job, specific tasks might fail, and then …
How to convert pdf to image on Linux command line
I have many PDF files, and I need to convert them to a png file format, add a border to those images, and convert back all those images to pdf …
How to Create Simple Shell Scripts in Linux
Creating shell scripts is one of the most essential skills that Linux users should have at the tip of their fingers. Shell scripts play an enormous role in automating repetitive …
How to check TLS/SSL certificate expiration date from command-line
How do I check the TLS/SSL certificate expiration date from my Linux or Unix shell prompt? How can I find the TLS certificate expiry date from Linux or Unix shell …
How to write the output into the file in Linux
How do I write the output into the file in Linux bash shell? Can you explain I/O redirection for both bash and POSIX shell to write data to the file …