Often you may want to use Bash to remove non-numeric characters from a string.
There are two common ways to do so:
Method 1: Use Pure Bash
new_var=${old_var//[!0-9]/
This particular example will remove all non-numeric characters from the string variable named old_var and save the results to a new variable named new_var.
Method 2: Use sed
new_var=$(echo $old_var | sed 's/[^0-9]*//g')
This particular example will also remove all non-numeric characters from the string variable named old_var and save the results to a new variable named new_var.
The following example shows how to use each of these methods in practice.
Example: How to Remove Non-Numeric Characters from String
Suppose we have the following string stored in a variable named id_number in Bash:
- HH5469JY
Suppose that we would like to remove all non-numeric characters so that we are left with the following string:
- 5469
One way to do so is by using the following syntax with pure Bash:
id_number="HH5469JY"
new=${id_number//[!0-9]/}
echo $new
The following screenshot shows how to use this syntax in practice:
Notice that when we use the echo statement to view the new variable named new we can see that it contains the following string:
- 5469
All of the non-numeric characters have been removed from the string.
Note that we could also use the following syntax with sed to achieve the same results:
id_number="HH5469JY"
new=$(echo $id_number | sed 's/[^0-9]*//g')
echo $new
The following screenshot shows how to use this syntax in practice:
Notice that when we use the echo statement to view the new variable named new we can see that it contains the following string:
- 5469
Feel free to use whichever method you prefer to remove all non-numeric characters from your own string.
Related Tutorials
The following tutorials explain how to perform other common tasks in Bash:
Bash: How to Remove Specific Characters from String
Bash: How to Check if String Starts with Specific Value
Bash: How to Count Number of Words in String
Bash: How to Count Number of Characters in String
