check if a string contains 2 instances of a character in bash code example
Example 1: checking if a substring exists in a string bash
string='Haystack';
if [[ $string =~ "Needle" ]]
then
echo "It's there!"
fi
Example 2: bash substring test
#!/bin/bash
STR='GNU/Linux is an operating system'
SUB='Linux'
if [[ "$STR" =~ .*"$SUB".* ]]; then
echo "It's there."
fi