Bash - check if number is less than

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

In this example, we use -lt operator to check if number is less than another number inside if statement.

script.sh file:

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#!/bin/bash

​

number=3

​

if [ "$number" -lt 5 ]; then

    echo "$number is less than 5"

fi

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

Run in command line:

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./script.sh

Output:

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3 is less than 5

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#!/bin/bash

​

number=3

​

if test "$number" -lt 5; then

    echo "$number is less than 5"

fi

Note: [ ] notation is shorthand of test command.

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#!/bin/bash

​

number=3

​

if [[ "$number" -lt 5 ]]; then

    echo "$number is less than 5"

fi

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

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#!/bin/bash

​

number=3

​

if (( "$number" < 5 )); then

    echo "$number is less than 5"

fi

Note: (( )) notation was created to simplyfy conditions (like in C language).

1. Bash - compare number variable to another number