How to delete an exact element in a bash array?

arrays bash unset
mateor picture mateor · Jan 10, 2013 · Viewed 9.3k times · Source

I am trying to remove just the first appearance of any one keyword from a bash array.

ARRAY=(foo bar and any number of keywords)
keywords=(red, rednet, rd3.0)

I remove the keyword like this: ARRAY=( ${ARRAY[@]/"$keyword"/} ) then if "red' is the first found keyword, it will strip 'red' from both keywords and return "foo bar net" instead of "foo bar rednet".

Edit: Here is example, hopefully this makes it clearer.

for keyword in ${ARRAY[@]}; do
      if [ "$keyword" = "red" ] || [ "$keyword" = "rd3.0" ] || [ "$keyword" = "rednet" ]; then
           # HERE IS TROUBLE
           ARRAY=( ${ARRAY[@]/"$keyword"/} )
           echo "ARRAY is now ${ARRAY[@]}"
           break
      fi
 done

Which if the ARRAY=(red rednet rd3.0) returns net rd3.0 instead of rednet rd3.0

If I use unset,: unset ${ARRAY["$keyword"]} bash complains if the rd3.0 is in the array: :syntax error: invalid arithmetic operator (error token is ".0") What is the safe way to unset or remove just an exact match from an array?

Answer

higuaro picture higuaro · Jan 10, 2013

Use the unset command with the array value at index, something like this: 

#!/usr/bin/env bash
ARRAY=(foo bar any red alpha number of keywords rd3.0 and)
keywords=(red, rednet, rd3.0)

index=0
for keyword in ${ARRAY[@]}; do
      if [ "$keyword" = "red" ] || [ "$keyword" = "rd3.0" ] || [ "$keyword" = "rednet" ]; then
           # HERE IS TROUBLE
           # ARRAY=( ${ARRAY[@]/"$p"/} )
           unset ARRAY[$index]
           echo "ARRAY is now: ${ARRAY[@]}"
           break
      fi
      let index++
 done

Related questions

Remove element from bash array by content (stored in variable) without leaving a blank slot

I have an array list in a bash script, and a variable var. I know that $var appears in ${list[@]}, but have no easy way of determining its index. I'd like to remove it from list. This answer achieves something …

Read More
Loop through an array of strings in Bash?

I want to write a script that loops through 15 strings (array possibly?) Is that possible? Something like: for databaseName in listOfNames then # Do something end

Read More
Split string into an array in Bash

In a Bash script I would like to split a line into pieces and store them in an array. The line: Paris, France, Europe I would like to have them in an array like this: array[0] = Paris array[1] = France array[2] = …

Read More