How can i delete an element in an array and then shift the array in Shell Script?

Question

First let me state my problem clearly:

Ex: Let's pretend this is my array, (the elements don't matter as in my actual code they vary):

array=(jim 0 26 chris billy 78 hello foo bar)

Now say I want to remove the following elements:

chris 78 hello

So I did: unset array[$i] while looping through the array. This removes the elements correctly, however, i end up with an array that looks like this:

array=(jim 0 26 '' billy '' '' foo bar)

I need it to look like this:

array=(jim 0 26 billy foo bar)

where jim is at index 0, 0@1, 26@2, etc..

How do I delete the elements in the array and move the other elements so that there are no null/empty spaces in the array?

Thanks!

chepner · Accepted Answer · 2013-11-30 01:58:56Z

27

Try this:

$ array=( "one two" "three four" "five six" )
$ unset array[1]
$ array=( "${array[@]}" )
$ echo ${array[0]}
one two
$ echo ${array[1]}
five six

Shell arrays aren't really intended as data structures that you can add and remove items from (they are mainly intended to provide a second level of quoting for situations like

arr=( "one two" "three four" )
somecommand "${arr[@]}"

to provide somecommand with two, not four, arguments). But this should work in most situations.

edited Nov 30, 2013 at 1:58

answered Jul 8, 2013 at 18:28

chepner

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1 Comment

tc90 Over a year ago

Sorry I am a bit late in marking this as correct. It helped me out. thanks.

Alexey Pismenny · Accepted Answer · 2016-11-04 15:00:38Z

4

See http://www.thegeekstuff.com/2010/06/bash-array-tutorial

Remove an Element from an Array

...

Unix=('Debian' 'Red hat' 'Ubuntu' 'Suse' 'Fedora' 'UTS' 'OpenLinux');

pos=3

Unix=(${Unix[@]:0:$pos} ${Unix[@]:$(($pos + 1))})

This contracts the array around pos, which the original poster wanted.

answered Nov 4, 2016 at 15:00

Alexey Pismenny

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Comments

mark_infinite · Accepted Answer · 2017-05-13 07:37:31Z

0

Try this:

user@pc:~$ array=(jim 0 26 chris billy 78 hello foo bar)
user@pc:~$ for itm2rm in chris 78 hello; do array=(\`echo ${array[@]} | sed "s/\<${itm2rm}\>//g"\`); done ; echo ${array[@]}
jim 0 26 billy foo bar

answered May 13, 2017 at 7:37

mark_infinite

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Clark Kent · Accepted Answer · 2017-12-10 07:25:21Z

0

this post had been revised and moved to its own post as a more in-depth tutorial how to remove an array element correctly in a for loop

edited Dec 10, 2017 at 7:25

answered Dec 10, 2017 at 2:48

Clark Kent

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