[2 days left] What’s wrong with your cloud strategy? Learn why multicloud solutions matter with Nimble Storage.Register Now

x
?
Solved

Bash Regular expression

Posted on 2010-09-16
6
Medium Priority
?
817 Views
Last Modified: 2012-05-10
The result of the following match is successful. Why?
 x=12345 ; [[ $x =~ ^[0-9]{3} ]] && echo 3 digits

I thought I wanted only 3 digits.  So to me it should have failed.  I was only expecting it to work for x=123.

Please explain.  Also if I want to match only 3 digits, what would be the regular expression?
0
Comment
Question by:farzanj
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
6 Comments
 
LVL 3

Expert Comment

by:kf4zmt
ID: 33696246
Are you saying it echoed "12345"?  It echoed 5 digits?
0
 
LVL 6

Accepted Solution

by:
DalHorinek earned 1000 total points
ID: 33696331
You need to

 [[ $x =~ ^[0-9]{3}$ ]]

Because otherwise it matches 3 numbers on the begining and then there can be anything ...

$ says that there can't be anything else.
0
 
LVL 4

Assisted Solution

by:Tachion
Tachion earned 800 total points
ID: 33696359
The reason it also works on 12345 (and 123abc for that matter) is that you only specify a match for the first 3 characters of the string to be numbers. You don't say "nothing may come after".

The following DOES work:

x=1234 ; [[ $x =~ ^[0-9]{3}$ ]] && echo 3 digits

The $ says, "nothing more".
0
Survive A High-Traffic Event with Percona

Your application or website rely on your database to deliver information about products and services to your customers. You can’t afford to have your database lose performance, lose availability or become unresponsive – even for just a few minutes.

 
LVL 33

Assisted Solution

by:pgnatyuk
pgnatyuk earned 200 total points
ID: 33696571
x=123 ; [[ $x = [0-9][0-9][0-9] ]] && echo 3 digits

says "3 digits" for '123' and not for '1234' or '12'.

I'm late. But I think, this is the simplest variant - nothing to explain, everything's clear
0
 
LVL 31

Author Comment

by:farzanj
ID: 33696739
Thanks for your help.  Appreciated
0
 
LVL 31

Author Comment

by:farzanj
ID: 33702007
I think due change of interface, I had awarded points but it did not go through.  Please open it again so that I can award points.  Thanks.
0

Featured Post

Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Utilizing an array to gracefully append to a list of EmailAddresses
Active Directory replication delay is the cause to many problems.  Here is a super easy script to force Active Directory replication to all sites with by using an elevated PowerShell command prompt, and a tool to verify your changes.
Connecting to an Amazon Linux EC2 Instance from Windows Using PuTTY.
Video by: Mark
This lesson goes over how to construct ordered and unordered lists and how to create hyperlinks.
Suggested Courses

656 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question