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Full Discussion: using regular expression in for loop
Top Forums Shell Programming and Scripting using regular expression in for loop Post 302405689 by drewk on Friday 19th of March 2010 02:09:18 PM
Old 03-19-2010
Learning the shell can be a bit eccentric sometimes ;-}

I >>think<< that you are confusing a few basic concepts.

Bash regular expressions would be more likely used in string manipulation.

You can read extensively about it here:

Manipulating Strings

Reading your code, it looks suspiciously like what you are trying to use is brace expansion of this type:

Code:
$ for var in {0..3}{1..9}; do echo -n "$var "; done
01 02 03 04 05 06 07 08 09 11 12 13 14 15 16 17 18 19 21 22 23 24 25 26 27 28 29 31 32 33 34 35 36 37 38 39

Double braces expansion is similar to a nested loop. This is not a great shortcuts for dates, however, since there are different number of days per month.

Single brace expansion is a great shortcut for this though:

Code:
$ # First day of every month in 2010:
$ for var in {1..12}; do echo -n "$var/1/2010 "; done 
1/1/2010 2/1/2010 3/1/2010 4/1/2010 5/1/2010 6/1/2010 7/1/2010 8/1/2010 9/1/2010 10/1/2010 11/1/2010 12/1/2010

or this:

Code:
$ # Every day in March 2010 (US Style...)
$ for var in {1..31}; do echo "3/$var/2010 "; done
3/1/2010 
3/2/2010 
3/3/2010 
3/4/2010 
3/5/2010 
3/6/2010 
3/7/2010 
3/8/2010 
3/9/2010 
3/10/2010 
3/11/2010 
3/12/2010 
3/13/2010 
3/14/2010 
3/15/2010 
3/16/2010 
3/17/2010 
3/18/2010 
3/19/2010 
3/20/2010 
3/21/2010 
3/22/2010 
3/23/2010 
3/24/2010 
3/25/2010 
3/26/2010 
3/27/2010 
3/28/2010 
3/29/2010 
3/30/2010 
3/31/2010

Last edited by drewk; 03-19-2010 at 03:17 PM..
 

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LEARN ABOUT BSD

re_comp

REGEX(3)						     Library Functions Manual							  REGEX(3)

NAME

       re_comp, re_exec - regular expression handler

SYNOPSIS

       char *re_comp(s)
       char *s;

       re_exec(s)
       char *s;

DESCRIPTION

       Re_comp	compiles a string into an internal form suitable for pattern matching.	Re_exec checks the argument string against the last string
       passed to re_comp.

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

       Re_exec 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 re_comp and re_exec may have trailing or embedded newline characters; they are terminated by nulls.  The regular
       expressions recognized are described in the manual entry for ed(1), given the above difference.

SEE ALSO

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

DIAGNOSTICS

       Re_exec returns -1 for an internal error.

       Re_comp returns one of the following strings if an error occurs:

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

3rd Berkeley Distribution					   May 15, 1985 							  REGEX(3)
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