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hpr1951 :: Some additional Bash tips

More about expansion in Bash: this time arithmetic expansion

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Hosted by Dave Morriss on 2016-01-25 is flagged as Explicit and is released under a CC-BY-SA license.
Bash, expansion, arithmetic expansion, shell arithmetic, number base. 2.
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Duration: 00:40:24

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.

Some additional Bash tips


As we saw in the last episode 1903 there are seven types of expansion applied to the command line in the following order:

  • Brace expansion (we looked at this subject in episode 1884)
  • Tilde expansion (seen in episode 1903)
  • Parameter and variable expansion (this was covered in episode 1648)
  • Command substitution (seen in episode 1903)
  • Arithmetic expansion
  • Word splitting
  • Pathname expansion

There is also another, process substitution, which occurs after arithmetic expansion on systems that can implement it.

We will look at one more of these expansion types in this episode but since there is a lot to cover, we'll continue in a later episode.

I have written out a moderately long set of notes about this subject and these are available here

Audio Note

This time, in the spirit of experimentation and as a way of learning Audacity I processed my audio thus:

  • Turned the stereo tracks to mono

  • Used a Noise Gate plug-in to reduce background noise (after "training" it on some silence)

  • Performed a Truncate Silence pass to reduce the length of pauses

  • Applied a small amount of amplification

Let me know if this had any positive or negative effects on the end product.


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Comment #1 posted on 2016-01-27 04:32:57 by Frank


This is a topic I've long wanted to know more about, if only to show off to my brother, who is Linux-curious, but sticks with Windows so he can play is antediluvian Star Wars game.

I look forward to working my way through your long show notes and learning stuff.

Comment #2 posted on 2016-01-27 13:50:59 by Dave Morriss

Thanks Frank

I'm glad you found it interesting. I hope the long notes help, I enjoyed researching and writing them.

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