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smart_sagittari 04-22-2005 02:04 AM

Using regular expression in filename

I have a script which gets as input a filename and does a grep on that. Now the problem is something like this:

The files I need to look in for the pattern are named as follows:

out, out.20050421.1234, out.20050421.2134, out.20050420.0012

My program gets as input the filename upto before the last . [DOT], like either, out [for the first file] or out.20050421 for the second and third files.

Now, in the second case [file name input out.20050421], I directly can use grep pattern out.20050421.[0-9]* to get results from the second and third files stated above [desired output]

However, if I get the filename as out, doing a out[0-9]* doesnt work [I dont know why]

Can someone give me a solution to this[assuming that I have not confused people enough]!!!

jailbait 04-23-2005 10:56 AM

"However, if I get the filename as out, doing a out[0-9]* doesnt work [I dont know why]"
Are you mising a period?
Shouldn't that be out.[0-9]*

Steve Stites

smart_sagittari 04-24-2005 10:02 PM

Thats the problem. The base file doesnt have a . [DOT]. How can I go abt this. Is there some way I can include a . inside the brackets [so as to consider it an optional dot]?

Dark_Helmet 04-25-2005 01:02 AM

I'm not sure your wildcard is doing what you hope it does (assuming this is a shell script and not perl).

In the shell, using "[0-9]*" says there must be a single character between 0 and 9 (inclusive), followed by any number of other characters. In other words, "out[0-9]*" would match:

It's not the same behavior as you'd get from a traditional regular expression.

You might want to consider using the '?' wildcard, but I don't know if that would really solve the problem.

smart_sagittari 04-25-2005 01:09 AM

Thanks for the suggestion. I shall certainly have a look into it.

Dark_Helmet 04-25-2005 01:20 AM

If you're using Bash, you'll be interested to read the secion regarding "pathname expansion". Specifically, the pattern matching sub-section. It explains how the wildcards work. In addition to the basic wildcards (*, ?, [] ), there are some expressions that have similar effects as traditional regular expressions. For instance:

      If the extglob shell option is enabled using the shopt builtin, several
      extended pattern matching operators are recognized.  In  the  following
      description, a pattern-list is a list of one or more patterns separated
      by a |.  Composite patterns may be formed using one or more of the fol-
      lowing sub-patterns:

                    Matches zero or one occurrence of the given patterns
                    Matches zero or more occurrences of the given patterns
                    Matches one or more occurrences of the given patterns
                    Matches exactly one of the given patterns
                    Matches anything except one of the given patterns

That's from my man page (bash version 3).

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