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what does this perl regex do

Posted on 2011-03-17
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$ScriptName     = $0;
$ScriptName     =~ s!^.*/!!;

I am trying to understand what does  this regex in a perl script do

thanks

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Question by:alienXeno
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3 Comments
 
LVL 84

Expert Comment

by:ozo
ID: 35154608
perl -mYAPE::Regex::Explain -e 'print YAPE::Regex::Explain->new(qr!^.*/!)->explain'
The regular expression:

(?-imsx:^.*/)

matches as follows:
 
NODE                     EXPLANATION
----------------------------------------------------------------------
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  ^                        the beginning of the string
----------------------------------------------------------------------
  .*                       any character except \n (0 or more times
                           (matching the most amount possible))
----------------------------------------------------------------------
  /                        '/'
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------


perldoc perlop
...
       s/PATTERN/REPLACEMENT/msixpogce
               Searches a string for a pattern, and if found, replaces that
               pattern with the replacement text and returns the number of
               substitutions made.  Otherwise it returns false (specifically,
               the empty string).



perldoc perlvar
...
       $PROGRAM_NAME
       $0      Contains the name of the program being executed.

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LVL 75

Accepted Solution

by:
käµfm³d   👽 earned 1000 total points
ID: 35156273
__NO POINTS__

The net effect of this regex is that everything from the start of the string up to and including the last occurrence of a forward slash will be replaced by an empty string. The exclamation points are pattern delimiters.
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Author Comment

by:alienXeno
ID: 35156359
thank you very much
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