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hpr3551 :: Bash snippet - some possibly helpful hints

Using 'eval', 'mapfile' and environment variables

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Hosted by Dave Morriss on 2022-03-14 is flagged as Explicit and is released under a CC-BY-SA license.
Bash, eval, mapfile, environment variables. 2.
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Duration: 00:24:35

Bash Scripting.

This is an open series in which Hacker Public Radio Listeners can share their Bash scripting knowledge and experience with the community. General programming topics and Bash commands are explored along with some tutorials for the complete novice.


I write a moderate number of Bash scripts these days. Bash is not a programming language as such, but it’s quite powerful in what it can do by itself, and with other tools it’s capable of many things.

I have enjoyed writing such scripts for many years on a variety of hardware and operating systems, and Bash is my favourite - partly because Linux itself is so flexible.

This is just a short show describing three things I tend to do in Bash scripts to assist with some tasks I find I need to undertake.

  1. Generate Bash variables from a text file - usually output from a program
  2. Fill Bash arrays with data from a file or other source
  3. Use environment variables to control the Bash script’s execution

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Comment #1 posted on 2022-03-20 20:26:20 by Some Guy On The Internet

Bash for the Win.

Hello Dave, How are you? I love the show; bash can be very simple or crazy complex depending on your needs. I haven’t used `eval` yet but now I have a reason to use it. Piping text from a file into a script to create commands sounds fun (and scary), so I’ll be experimenting on a Raspberry Pi; so I don’t end the night crying while restoring from a backup, again. Thanks for the show!

Comment #2 posted on 2022-03-21 17:14:44 by Dave Morriss


I appreciate the feedback. Yes, Bash has a lot of power and can be used for many things.

You are right, a Raspberry Pi is a great test bed; I use them often.

I hope you found the show useful. Let us know if you find better ways of doing these types of things.

Best wishes, Dave

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