Validating input with regular expression in bash

Question

I have used the example from http://www.regular-expressions.info/examples.html to validate the following code

while [[ ! $name =~ ^[a-Z][ \t][a-Z]. ]]; do

                echo "Please enter your Firstname and Surname e.g Joe Bloggs"                           # (a)Ask for NAME,TELEPHONE NUMBER,DOB #
                read name
                echo
        done

I am quite simply looking to ensure user enters first and second name with a space any help would be greatly appreciated!

@CodeGnome, no =~ is correct.

Anders Johansson
– Anders Johansson

2013-01-20 23:27:13 +00:00
Commented Jan 20, 2013 at 23:27 — Anders Johansson
– Anders Johansson, Commented Jan 20, 2013 at 23:27

Anders Johansson · Accepted Answer · 2013-01-20 23:19:26Z

4

There are several problems with your regex:

You're checking for characters between a (lowercase) and Z (uppercase). This won't do what you expect, use [A-Za-z] to check both upper and lowercase letters.
You're missing repeat characters; use + to match one or more characters.
The end-of-match should be $, not . (which matches any single character).

Try this:

^[A-Za-z]+[\ \t][A-Za-z]+$

If you want to validate Uppercased first and last names you could use:

^[A-Z][a-z]+[\ \t][A-Z][a-z]+$

But this would not work with names like Marty McFly that don't follow that rule.

edited Jan 20, 2013 at 23:19

answered Jan 20, 2013 at 23:09

Anders Johansson

4,05622 silver badges19 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Tricky Dicky Over a year ago

Sorry getting these errors: line 14: syntax error in conditional expression line 14: syntax error near \t][A-Za-z]+$' line 14: while [[ ! $name =~ ^[A-Za-z]+[ \t][A-Za-z]+$ ]]; do'

Anders Johansson Over a year ago

@Tricky Dicky, thanks, I forgot to add a backslash to escape the space in the regex, updated the answer.

Collectives™ on Stack Overflow

Validating input with regular expression in bash

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related