Bash: How to Extract First Number from a String

Often you may want to use Bash to extract the first number in a particular string.

You can use the following syntax to do so:

echo $my_string | sed -E 's,^[^0-9]*([0-9]+).*$,\1,'

This particular example will extract the first number from the string variable named my_string.

Note that if a number in a string contains a decimal point then this syntax will extract only the number before the decimal point.

The following example shows how to use this syntax in practice.

Example: How to Extract First Number from a String in Bash

Suppose we have the following string that represents the employee ID for a manager at a particular company:

Suppose that we would only like to extract 1430, which represents the first number in this string.

We can use the following syntax to do so:

employee_ID="Manager1430Department15"
echo $employee_ID | sed -E 's,^[^0-9]*([0-9]+).*$,\1,'

The following screenshot shows how to use this syntax in practice:

Bash extract first number from string

Notice that this returns 1430, which represents the first number in the string.

Suppose instead that we had the following string:

We can use the same syntax to extract the first number before the decimal place from the string:

employee_ID="Manager1430.552Department15"
echo $employee_ID | sed -E 's,^[^0-9]*([0-9]+).*$,\1,'

The following screenshot shows how to use this syntax in practice:

Bash extract first number before decimal in string

Notice that this returns 1430, which represents only the first number before the decimal place in the employee ID.