Check if a Bash array contains a value

Question

In Bash, what is the simplest way to test if an array contains a certain value?

Answer 1

After having answered, I read another answer that I particularly liked, but it was flawed and downvoted. I got inspired and here are two new approaches I see viable.

array=("word" "two words") # let's look for "two words"

using grep and printf:

(printf '%s\n' "${array[@]}" | grep -x -q "two words") && <run_your_if_found_command_here>

using for:

(for e in "${array[@]}"; do [[ "$e" == "two words" ]] && exit 0; done; exit 1) && <run_your_if_found_command_here>

For not_found results add || <run_your_if_notfound_command_here>

Answer 2

a=(b c d)

if printf '%s\0' "${a[@]}" | grep -Fqxz c
then
  echo 'array “a” contains value “c”'
fi

If you prefer you can use equivalent long options:

--fixed-strings --quiet --line-regexp --null-data

Answer 3

This is working for me:

# traditional system call return values-- used in an `if`, this will be true when returning 0. Very Odd.
contains () {
    # odd syntax here for passing array parameters: http://stackoverflow.com/questions/8082947/how-to-pass-an-array-to-a-bash-function
    local list=$1[@]
    local elem=$2

    # echo "list" ${!list}
    # echo "elem" $elem

    for i in "${!list}"
    do
        # echo "Checking to see if" "$i" "is the same as" "${elem}"
        if [ "$i" == "${elem}" ] ; then
            # echo "$i" "was the same as" "${elem}"
            return 0
        fi
    done

    # echo "Could not find element"
    return 1
}

Example call:

arr=("abc" "xyz" "123")
if contains arr "abcx"; then
    echo "Yes"
else
    echo "No"
fi

Answer 4

given :

array=("something to search for" "a string" "test2000")
elem="a string"

then a simple check of :

if c=$'\x1E' && p="${c}${elem} ${c}" && [[ ! "${array[@]/#/${c}} ${c}" =~ $p ]]; then
  echo "$elem exists in array"
fi

where

c is element separator
p is regex pattern

(The reason for assigning p separately, rather than using the expression directly inside [[ ]] is to maintain compatibility for bash 4)

Answer 5

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

Answer 6

I typically just use:

inarray=$(echo ${haystack[@]} | grep -o "needle" | wc -w)

non zero value indicates a match was found.