kpc00@JUTS.ccc.amdahl.com (kpc) (10/27/90)
OK, I've got perl now.
1. How good is pl36 a2p supposed to be, in general? I've got a
5-page nawk program that doesn't compile right, and when it is
transformed into simpler expressions (I had some nested assignments,
getlines, and increment operations in a blockless loop), it wouldn't
run. I added commas to some print statements to make it run, but it
didn't run correctly. Oh, well. I'm just wondering how much effort
I'd be likely to have to put into it to get it to run in perl (the
point of doing which is mainly to evaluate perl, since the nawk script
works quite well running in nawk in most cases).
2. Since I can't quite use the above-mentioned nawk program for
comparative cyberlinguistics (:-)), I would really find it very
helpful to see how a very simple shell script is best converted into
perl. (O.K., "There Is M.T.O.W. To Do It": I would be happy to see
several, or even many, versions.)
How would the following simple safe-copy script be converted elegantly
or efficiently, preserving its semantics? (Ideally, the file would
contain both a perl and an sh script, and would execute the sh script
on any machine where perl is not available. Would this use the END
literal somehow?)
==========
:
#
#kcp
#
#non destructive cp and mv and ln.
#
#use getopts
trashdir=${TRASHDIR:?`no trashdir`}
#using CMD=/bin/`basename $0` instead is possible, but undesirable
if [ "$1" = '-R' ] #rm
then
/bin/mv $* $trashdir
exit 0
elif [ "$1" = '-m' ] #mv
then
CMD=/bin/mv
shift
elif [ "$1" = '-l' ] #ln
then
CMD=/bin/ln
shift
else #cp
CMD=/bin/cp
fi
if [ $# -lt 2 ]
then
echo usage: cp file1 file2 or cp file+ dir 1>&2
echo usage: -m moves; -l hard-links. \(too few args\) 1>&2
exit 1
fi
#set -A and $# in ksh
#just ${`eval $#`}
for i
do
lastarg=$i
done
if [ ! -d $lastarg ]
then
if [ $# -ne 2 ]
then
echo usage: cp file1 file2 or cp file+ dir 1>&2
echo usage: -m moves; -l hard-links. \(too many args\) 1>&2
exit 1
fi
if [ -f $2 -a -f $1 ]
then
#copy preserves permissions of target
#we want ctime changed, mtime preserved, and atime preserved
#possibly use mv and chmod, being careful with linked files
#possibly use cp and a touch equivalent.
echo kcp: copying $2 to trash first. 1>&2
/bin/cp $2 $trashdir
fi
$CMD $1 $2
else
for eachfile
do
if [ $eachfile != $lastarg ]
then
file=$lastarg/`basename $eachfile`
if [ -f $file -a -f $eachfile ]
then
echo kcp: copying $file to trash first. 1>&2
/bin/cp $file $trashdir
fi
$CMD $eachfile $file
fi
done
fi
==========
3. Is perl one of the fastest interpreters around? That, along with
its system call interface, seems to be its strongest point. How does
it compare to various Schemes, I wonder? (And are there any good
Lisps that can do pattern matching as well as perl does?)
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