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Full Discussion: Regular expression help
Top Forums UNIX for Dummies Questions & Answers Regular expression help Post 302757955 by frodo61 on Friday 18th of January 2013 08:36:29 AM
Old 01-18-2013
Quote:
Originally Posted by radoulov
Your regular expression matches: zero or more occurrences of [0-9] followed by a literal dot ., followed by zero or more occurrences of [0-9].
The == / != operators in ksh don't support regular expressions, but only shell pattern matching.
As I already said, check if your ksh version supports the =~ operator (but I doubt, if it's really an x88 implementation).
You should also modify the pattern (if used as a regular expression) to restrict the matching (see the examples in the previous two posts).

If your shell doesn't support regular expressions, use grep, as balajesuri suggested (you may need to use > /dev/null
instead of -q with some grep implementations.
Thank you for explaining. If my shell doesnt support regular expressions why does some of the regular expression work in my code? The =~ didnt work by the way. I will try usng the grep example instead but how would I make a single dot optionally instead of mandatory, would it be \? after the dot?

Thanks
 

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regex(3)						     Library Functions Manual							  regex(3)

Name
       re_comp, re_exec - regular expression handler

Syntax
       char *re_comp(s)
       char *s;

       re_exec(s)
       char *s;

Description
       The  subroutine	compiles  a string into an internal form suitable for pattern matching.  The subroutine checks the argument string against
       the last string passed to

       The subroutine returns 0 if the string s was compiled successfully; otherwise a string containing an  error  message  is  returned.  If	is
       passed 0 or a null string, it returns without changing the currently compiled regular expression.

       The  subroutine returns 1 if the string s matches the last compiled regular expression, 0 if the string s failed to match the last compiled
       regular expression, and -1 if the compiled regular expression was invalid (indicating an internal error).

       The strings passed to both and may have trailing or embedded newline characters; they are terminated by	nulls.	 The  regular  expressions
       recognized are described in the manual entry for given the above difference.

Diagnostics
       The subroutine returns -1 for an internal error.

       The subroutine returns one of the following strings if an error occurs:

       No previous regular expression
       Regular expression too long
       unmatched (
       missing ]
       too many () pairs
       unmatched )

See Also
       ed(1), ex(1), egrep(1), fgrep(1), grep(1)

																	  regex(3)
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