CODEWITHSUNDEEP
regexpcrepcregrep
nhavens
nhavens

Reputation: 352

PCRE regex whitespace

I am trying to write a regex to pull all non-comment and non-empty lines from /etc/samba/smb.conf. Comments are lines that:

  1. start with #
  2. start with ;
  3. start with any amount of whitespace followed immediately by either # or ;

I tried the following, but it did not properly handle comment type 3.

grep -P '^\s*[^#;]' /etc/samba/smb.conf

This one worked for all 3 types of comments:

grep -P '^\s*[^#;\s]' /etc/samba/smb.conf

Can you explain why adding \s to the character class successfully filtered out comment type 3?

Upvotes: 2

Views: 1975

Answers (2)

vks
vks

Reputation: 67968

The problem here is partial matches as you have not used an end anchor $.

In case of example 3 

      ;

There will be partial matching upto ; done by \s*.In the other regex you have disabled \s so it will not capture the space and partial match is disabled.

The correct regex here is

 (?m)^(?!\s*[#;]).+$

See demo

Upvotes: 1

Wouter J
Wouter J

Reputation: 41934

[^...] means does not match any of the characters given at the place of ....

You need: ^\s*[#;].

Upvotes: 1

Related Questions