Check if substring is present in string or array using bash – Code Example

Code Example –

1. Check on string

#!/bin/bash

var="This is a string"

[[ $var == *is* ]] && echo "string matched"

# Output:
# string matched

2. Check on array –

#!/bin/bash

arr=("This" "is a" "string")

[[ ${arr[*]} == *is* ]] && echo "array matched"

# Output:
# array matched

3. Check if NOT in string

#!/bin/bash

var="This is a string"

([[ $var != *is* ]] && echo "string matched") || echo "string not matched"

# Output:
# string not matched

4. Using if conditions –

#!/bin/bash

if [[ $var == *sub_string* ]]; then
    printf '%s\n' "sub_string is in var."
fi

# Inverse (substring not in string).
if [[ $var != *sub_string* ]]; then
    printf '%s\n' "sub_string is not in var."
fi

# This works for arrays too!
if [[ ${arr[*]} == *sub_string* ]]; then
    printf '%s\n' "sub_string is in array."
fi

5. Using switch conditions –

case "$var" in
    *sub_string*)
        # Do stuff
    ;;

    *sub_string2*)
        # Do more stuff
    ;;

    *)
        # Else
    ;;
esac