Expansion, matching, files

Expansion, matching, files

[Jerry Rocteur]

Hi,

I'm playing with something that is bugging me...

I want to find if a file exists either ff.log or ll.log for example

Now to do this with pattern maching is easy:

I create my file for example
 touch ff.log
 ll *log
-rw-r--r-- 1 jro softdev 0 Nov 12 10:40 ff.log

for f in *
do
[[ $f == (ff|ll).log ]] && echo Yes
done
Yes

This also works of course:

 print (ff|ll).log
ff.log


But I would like to do this:

[[ -e (cc|ff).log ]] && echo yes
zsh: parse error near `('

Can I use this kind of pattern in an if statement ?

NOTE: I know I could do [[ -e ff.log || -e ll.log ]] && echo yes

But that would not be fun nor simple to type if for example you wanted to test ([a-z][5-6]).log

Thanks in advance,

Jerry

Re: Expansion, matching, files

[Peter Stephenson]

"Jerry Rocteur" wrote:
> But I would like to do this:
> 
> [[ -e (cc|ff).log ]] && echo yes
> zsh: parse error near `('
> 
> Can I use this kind of pattern in an if statement ?

No, an "if" doesn't do file globbing.

The usual way of doing this is just to go the glob with the (N) flag
which removes anything that doesn't match.  There are various ways of
doing this, for example

  array=((cc|ff).log(N))
  if (( $#array )); then
    # something there
  else
    # not
  fi

or if you want to make this more generic

  exists() {
    local -a array
    array=(${^~*}(N))
    (( $#array ))
  }
  exists '(cc|ff).log' && echo yes

Note the quotes in the second case; you don't want the pattern expanded
until it gets the (N) on the end.  "exists" as defined can take multiple
pattern arguments which are "or"ed.

-- 
Peter Stephenson <pws@csr.com>            Software Engineer
Tel: +44 (0)1223 692070                   Cambridge Silicon Radio Limited
Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, UK


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