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hpr2719 :: Bash Tips - 17

Arrays in Bash (part 2)

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Hosted by Dave Morriss on Thursday, 2019-01-03 is flagged as Explicit and is released under a CC-BY-SA license.
Bash, array, indexed array, associative array. 2.
The show is available on the Internet Archive at: https://archive.org/details/hpr2719

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Duration: 00:34:16

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.

Bash Tips - 17 (Additional auxiliary Bash tips)

Arrays in Bash

This is the second of a small group of shows on the subject of arrays in Bash. It is also the seventeenth show in the Bash Tips sub-series.

In the last show we saw the two types of arrays, and learned about the multiple ways of creating them and populating them. We also looked at how array elements and entire arrays are accessed.

Now we want to continue looking at array access and some of the various parameter expansion operations available.

Long notes

I have provided detailed notes as usual for this episode, and these can be viewed here.


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Comment #1 posted on 2019-01-07 17:03:00 by Ken Fallon

Things I didn't know

Didn't know about Substring manipulation

Also found out why the following works


filepath=$(dirname -- "${source}")
filename=$(basename -- "${source}")
extension="${filename##*.}"
filename="${filename%.*}"

Comment #2 posted on 2019-01-07 19:18:46 by Dave Morriss

Substring manipulation

This is a very cool feature which I use a lot!

I'd approach your example with a little script, 'pathparse' which shows you don't need 'dirname' or 'basename':

$ cat pathparse
#!/usr/bin/env bash

path="$1"

directory="${path%/*}"
filename="${path##*/}"
prefix="${filename%.*}"
suffix="${filename#*.}"

printf '%-9s: %s\n' \
'Directory' "$directory" \
'Filename' "$filename" \
'Prefix' "$prefix" \
'Suffix' "$suffix"

$ ./pathparse /etc/apt/sources.list
Directory: /etc/apt
Filename : sources.list
Prefix : sources
Suffix : list

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