On 6 June 2013 13:41, Eric Blake wrote: > > A more robust, (and more portable), formulation may be: > > > > echo $var | grep '^+\{0,1\}[0-9]\{1,\}$' > /dev/null 2>&1 > > Why fork, when straight shell will do? > > case $var in > ... > Agreed, avoiding the fork is a good idea, and I do often use case statements myself, much as you suggest, (although it may be considered a less obvious solution). My point was more that the OP's use of grep didn't use a particularly effective expression for his (perceived) task, and that his use of grep options wasn't portable. -- Regards, Keith. _______________________________________________ Autoconf mailing list Autoconf@xxxxxxx https://lists.gnu.org/mailman/listinfo/autoconf