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Full Discussion: Understanding sed
Top Forums Shell Programming and Scripting Understanding sed Post 302774427 by alister on Friday 1st of March 2013 10:54:17 PM
Old 03-01-2013
Quote:
Originally Posted by gary_w
Question: if this sed command was in a script, could it be commented like I did above in the code? Can a sed regex be multi-line with comments?
Nope. You can have comments in a sed script, but not within a regular expression. What you are asking is possible with perl if you use the /x regular expression modifier.

Regards,
Alister

---------- Post updated at 10:54 PM ---------- Previous update was at 10:49 PM ----------

Quote:
Originally Posted by gary_w
One could also do:
Code:
s/:[^:]*:/::/

s/:[^:]*/:/ would work just as well, unless it's necessary to prevent the last field in a line without a trailing colon from matching, or even s/[^:]*//2.

REgards,
Alister
 

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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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