[Code Example] Check if string starts with substring or not using bash

Code Example –

1. Check if substring is at the start –

#!/bin/bash

var="This is a string"

if [[ $var == Th* ]]; then
    printf '%s\n' "var starts with sub_string."
fi

# Output:
# var starts with sub_string.

2. Check if substring is not at the start –

#!/bin/bash

var="This is a string"

if [[ $var != is* ]]; then
    printf '%s\n' "var does not start with sub_string."
fi

# Output:
# var does not start with sub_string.

3. Check if substring is at the start of array –

#!/bin/bash

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

if [[ ${arr[*]} == Th* ]]; then
    printf '%s\n' "sub_string is in start of array."
fi

# Output:
# sub_string is in start of array.

4. Check if substring is not at the start of the array –

#!/bin/bash

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

if [[ ${arr[*]} != is* ]]; then
    printf '%s\n' "sub_string is not in start of array."
fi

# Output:
# sub_string is not in start of array.