Bash: check if an array contains a value

There is sample code that shows how to replace a substring from an array. You can make a copy of the array and try to remove the target value from the copy. If the copy and original are then different, then the target value exists in the original string.

The straightforward (but potentially more time-consuming) solution is to simply iterate through the entire array and check each item individually. This is what I typically do because it is easy to implement and you can wrap it in a function (see this info on passing an array to a function).

for i in "${array[@]}"
do
    if [ "$i" -eq "$yourValue" ] ; then
        echo "Found"
    fi
done

For strings:

for i in "${array[@]}"
do
    if [ "$i" == "$yourValue" ] ; then
        echo "Found"
    fi
done

If you want to do a quick and dirty test to see if it's worth iterating over the whole array to get a precise match, Bash can treat arrays like scalars. Test for a match in the scalar, if none then skipping the loop saves time. Obviously you can get false positives.

array=(word "two words" words)
if [[ ${array[@]} =~ words ]]
then
    echo "Checking"
    for element in "${array[@]}"
    do
        if [[ $element == "words" ]]
        then
            echo "Match"
        fi
    done
fi

This will output "Checking" and "Match". With array=(word "two words" something) it will only output "Checking". With array=(word "two widgets" something) there will be no output.

$ myarray=(one two three)
$ case "${myarray[@]}" in  *"two"*) echo "found" ;; esac
found

Here is a small contribution :

array=(word "two words" words)  
search_string="two"  
match=$(echo "${array[@]:0}" | grep -o $search_string)  
[[ ! -z $match ]] && echo "found !"  

Note: this way doesn't distinguish the case "two words" but this is not required in the question.

Below is a small function for achieving this. The search string is the first argument and the rest are the array elements:

containsElement () {
  local e
  for e in "${@:2}"; do [[ "$e" == "$1" ]] && return 0; done
  return 1
}

A test run of that function could look like:

$ array=("something to search for" "a string" "test2000")
$ containsElement "a string" "${array[@]}"
$ echo $?
0
$ containsElement "blaha" "${array[@]}"
$ echo $?
1

containsElement () { for e in "${@:2}"; do [[ "$e" = "$1" ]] && return 0; done; return 1; }

Now handles empty arrays correctly.