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

One-line solution

printf '%s\n' "${myarray[@]}" | grep -P '^mypattern$'

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Explanation

The printf statement prints each element of the array on a separate line.

The grep statement uses the special characters ^ and $ to find a line that contains exactly the pattern given as mypattern (no more, no less).

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Usage

To put this into an if ... then statement:

if printf '%s\n' "${myarray[@]}" | grep -q -P '^mypattern$'; then
    # ...
fi

I added a -q flag to the grep expression so that it won't print matches; it will just treat the existence of a match as "true."