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From: gt0178a@prism.gatech.EDU (BURNS,JIM)
Newsgroups: comp.unix.questions
Subject: Re: KSH script arguments
Message-ID: <13160@hydra.gatech.EDU>
Date: 30 Aug 90 02:33:49 GMT
References: <b4CC02oVc3Jx01@amdahl.uts.amdahl.com>
Distribution: comp.unix.questions
Organization: Georgia Institute of Technology
Lines: 72

in article <b4CC02oVc3Jx01@amdahl.uts.amdahl.com>, jonc@uts.amdahl.com (Jonathan Chang) says:
> How can I extract the last argument to a ksh script?

I'll answer your question 2 different ways. The more generic approach
would be to set each element of $* to a ksh array variable:

set a b c                              #set "command line parameters"
j=0                                    #index variable
for i                                  #no parameters means use $*
do
arr[$j]=$i                             #set each array element
j=`expr $j + 1`                        #incr. index - spaces ARE significant
done
j=0
for i                                  #echo values in a diff. loop
do
echo 'arg #'$j' is '${arr[$j]}
j=`expr $j + 1`
done
echo ${arr[`expr $# - 1`]}             #last 2 stmts are equiv. for pos. parms.
j=`expr ${#arr[*]} - 1`;echo ${arr[$j]}# but this one is more array generic

its output is:

arg #0 is a
arg #1 is b
arg #2 is c
c
c

The second sol'n is a function I use to replace 'cp' to check that the
last argument to 'cp' resulting from a wildcard expansion is a directory
if the # of parms > 2. Old habits from MSDOS die hard, and I'm always
doing 'cp *pat' thinking that the 'destination' will default to my current
directory. It offers no protection from overwriting the last file on the
expanded command tail if the # of parms = 2. I just loop to find the last
parm.

cp () {
if [ $# -eq 0 ]
   then /bin/cp                        #let /bin/cp print error msg
else
   for i in $@                         #find last parm
   do
      continue
   done
   if [ $# -le 2 -o -d $i ]            #ok if # parms = 2, or last parm is
      then /bin/cp $@                  #directory. /bin/cp prints error msg
   else                                #if # parms = 1
      echo $i: not a directory
   fi
   unset i
fi
}

Note that ksh will complain about $* not being set if you provide no parms
and the ksh flag 'nounset' is on. Use 'set -o' to check your flags, and
'set +o nounset' to turn it off.

Just for fun, here's the same function in csh. It's a little less clean
since I can't get 'if..then..else' to work inside a alias. The 'set j=
garbage string' if the # of parms = 0 just sets a bogus directory name so
that the remaining if's don't croak on an unset $j. Note the body of the
alias is one line.

alias cp \
'set i=(\!*);set j=$i[$#i];if ( $#i == 0 ) /bin/cp;if ( $#i == 0 ) set j=CB6EHVC;if ( $#i == 1 || $#i == 2 || -d $j ) /bin/cp \!*;if ( $#i >= 3  && \! -d $j && $j \!= CB6EHVC ) echo ${j}: not a directory;unset i;unset j'
-- 
BURNS,JIM
Georgia Institute of Technology, Box 30178, Atlanta Georgia, 30332
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