Problem with Splitting Up a String and Putting it Into an Array in BASH on a Mac

Question

I have been trying to split up a string and putting it into an Array in Bash on my Mac without success.

Here is my sample code:

#!/bin/bash
declare -a allDisks
allDisksString="`ls /dev/disk* | grep -e 'disk[0-9]s.*' | awk '{ print $NF }'`"
#allDisksString="/dev/disk0s1 /dev/disk1s1"
echo allDisksString is $allDisksString
IFS=' ' read -ra allDisks <<< "$allDisksString"
echo allDIsks is "$allDisks"
echo The second item in allDisks is "${allDisks[1]}"
for disk in "${allDisks[@]}"
do
    printf "Loop $disk\n"
done

And below is the output:

allDisksString is /dev/disk0s1 /dev/disk0s2 /dev/disk0s3 /dev/disk0s4 /dev/disk1s1
allDIsks is /dev/disk0s1
The second item in allDisks is 
Loop /dev/disk0s1

Interesting if I execute the following in the Mac Terminal:

ls /dev/disk* | grep -e 'disk[0-9]s.*' | awk '{ print $NF }'

I get the following output

/dev/disk0s1
/dev/disk0s2
/dev/disk0s3
/dev/disk0s4
/dev/disk1s1

So I have also tried setting IFS to IFS=$'\n' without any success.

So no luck in getting a list of my drives into an array.

Any ideas on what I am doing wrong?

Barmar · Accepted Answer · 2020-09-17 22:44:14Z

2

You're making this much more complicated than it needs to be. You don't need to use ls, you can just use a wildcard to match the device names you want, and put that in an array assignment.

#!/bin/bash

declare -a allDisks
allDisks=(/dev/disk[0-9]s*)
echo allDIsks is "$allDisks"
echo The second item in allDisks is "${allDisks[1]}"
for disk in "${allDisks[@]}"
do
    printf "Loop $disk\n"
done

answered Sep 17, 2020 at 22:44

Barmar

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2 Comments

RobK Over a year ago

P.S. There is an small error in your code that was carried over from my code. The third line in your code above really should be: echo allDIsks is "${allDisks[*]}"

Barmar Over a year ago

It's only an error if you really intended to print the whole array.

choroba · Accepted Answer · 2020-09-17 22:36:19Z

0

read only reads one line.

Use an assignment instead. When assigning to an array, you need to use parentheses after the = sign:

#!/bin/bash
disks=( $(ls /dev/disk* | grep -e 'disk[0-9]s.*' | awk '{ print $NF }') )
echo ${disks[1]}

answered Sep 17, 2020 at 22:36

choroba

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