Bash - check if string is less than (ASCII alphabetical order)

In this article, we would like to show you how to check if check if string is less than another string in Bash.

Practical example

In this example, we use escaped < operator to check if string is less than another string (in ASCII alphabetical order) inside the if statement.

script.sh file:

#!/bin/bash

string="aaa"

if [ "$string" \< "bbb" ]; then
    echo "The $string is less than bbb"
fi

Note: this approach should be used in POSIX shells where other solutions may not work.

Run in command line:

./script.sh

Output:

The aaa is less than bbb

Altermative notation

1. test based solution

#!/bin/bash

string="aaa"

if test "$string" \< "bbb"; then
    echo "The $string is less than bbb"
fi

Note: [ ] notation is shorthand of test command.

2. [[ ]] based solution

#!/bin/bash

string="aaa"

if [[ "$string" < "bbb" ]]; then
    echo "The $string is less than bbb"
fi

Note: [[ ]] notation is like extended test command, adding additional features (e.g. regular expressions).

See also

1. Bash - check if string is equal to

2. Bash - check if string is not equal to

3. Bash - check if string is greater than (ASCII alphabetical order)