Date: Tue, 6 Apr 1999 22:35:18 +0200 (CEST) From: Oliver Fromme <olli@dorifer.heim3.tu-clausthal.de> To: freebsd-stable@FreeBSD.ORG Subject: Re: preventing periodic yossarian's syndrome Message-ID: <199904062035.WAA27862@dorifer.heim3.tu-clausthal.de>
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Randy Bush wrote in list.freebsd-stable:
> for emacs users who get periodic yossarian's syndrome ("i see everything
> twice!"), a hack on the order of the appended would be nice. though i hope
> someone has a better way of doing the backticked expression.
> [...]
> ! if [ -x $file -a ! -d $file -a ! `echo $file | grep \~` ] ; then
> $file
> fi
Just a suggestion:
The following ist much more efficient, because "case" is a
shell-builtin, therefore it saves several forks/execs. Also,
"$file" should be enclosed in double quotes to protect it
from the shell if it contains special characters.
if [ -x "$file" -a ! -d "$file" ] ; then
case "$file" in
*~*) ;;
*) "$file";;
esac
fi
As a general rule of thumb, it's always better to use case
instead of grep in shell scripts if a variable is to be
compared against a pattern that can be expressed using shell
globbing. This can give a significant speed-up, especially
in loops.
Regards
Oliver
--
Oliver Fromme, Leibnizstr. 18/61, 38678 Clausthal, Germany
(Info: finger userinfo:olli@dorifer.heim3.tu-clausthal.de)
"In jedem Stück Kohle wartet ein Diamant auf seine Geburt"
(Terry Pratchett)
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