This is a text-only version of the following page on https://raymii.org:
---
Title       : 	Bash Bits: Check if item is in array
Author      : 	Remy van Elst
Date        : 	21-09-2013
URL         : 	https://raymii.org/s/snippets/Bash_Bits_Check_If_Item_Is_In_Array.html
Format      : 	Markdown/HTML
---



Bash Bits are small examples, tips and tutorials for Bash (Scripts). This bash
bit shows you how find out if an array has an item.

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[All Bash Bits can be found using this link][2]

This is a simple function which helps you find out if an (non associative) array
has an item. It allows you to call the function with just the array name, not
${arrayname[@]}. It returns 1 if the item is in the array, and 0 if it is not.

This is the function:

    
    
    in_array() {
        local haystack=${1}[@]
        local needle=${2}
        for i in ${!haystack}; do
            if [[ ${i} == ${needle} ]]; then
                return 0
            fi
        done
        return 1
    }
    

Now we can test it and see that it works:

    
    
    declare -a vpsservers=("vps1" "vps2" "vps3" "vps4" "vps6");
    
    in_array vpsservers vps3 && echo "found" || echo "not found"
    in_array vpsservers vps5 && echo "found" || echo "not found"
    

Should return:

    
    
    found
    not found
    

Now a usage example. Lets say you have a script which requires a specific
version of Ubuntu and does not work on other versions of ubuntu. You can use
this to check if the version of ubuntu is supported with this function.

    
    
    declare -a supported_ubuntu=("Ubuntu 10.04.1 LTS" "Ubuntu 10.04.3 LTS" "Ubuntu 10.04.4 LTS" "Ubuntu 10.10" "Ubuntu 12.04 LTS" "Ubuntu 12.04.1 LTS")
    
    if [ -f "/etc/lsb-release" ]; then
        running_ubuntu=`awk -F "\"" '/DESCRIPTION/ { print $2 }' /etc/lsb-release`
        if in_array supported_ubuntu "${running_ubuntu}"; then
            echo "${running_ubuntu} is supported."
        else
            echo "${running_ubuntu} is not supported. Run ${0} again with the -f option to ignore this warning."
            exit 1
        fi
    fi
    

Do note that forcing a specific version of something is not a best practice,
however sometimes you are forced to.

   [1]: https://www.digitalocean.com/?refcode=7435ae6b8212
   [2]: https://raymii.org/s/tags/bash-bits.html

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