Re: Scripting help

[Jan]

Jon Haugsand wrote:

* [EMAIL PROTECTED]

IFS=':'
cat /etc/passwd | while read a b c d
do
   if [[ "$a" == "root" ]]
   then
      export NAME="$c"
   fi
done

- in ksh this will export NAME into your current env, but not in
bash. The explanation, I understand, is that when you start a pipeline
in ksh, the last command in the pipeline (here: where ...) runs in the
current shell, but in bash all the commands in a pipeline run in a
subshell.

This does not work in ksh on my RedHat 8.0.  Neither shell do what you
say.

Really? I haven't tried ksh on Linux other than seeing that it is there. However, I have recently done extensive (and portable) shell scripting in ksh on AIX (4 and 5), SunOS (5.6, 5.7, and 5.8) and HP-UX (11 and 11i) as well as Tru64 (AKA OSF1) and Linux. The script above works on all platforms except Linux. The ksh, BTW, is a free version whereas the ones on the other UNIXes are proprietary, of course, so there may be some incompatibilities.

As I said this is only a minor annoyment, but it does mean that in
bash you have to use an intermediate file:

IFS=':'
cat /etc/passwd > tempfile
while read a b c d
do
   if [[ "$a" == "root" ]]
   then
      export NAME="$c"
   fi
done < tempfile
rm tempfile

Ah no.  You do it like this:

 NAME=`IFS=':'
 cat /etc/passwd | while read a b c d; do
  if [[ "$a" == "root" ]]; then
     echo $c
  fi
 done`

That's a good tip - thank you! However, that only works if we're talking about 1 env variable. In my work it was actually a number of arrays, and I don't thik there's an easy way to implement that along the same lines. And a good tip in return: instead of `command` use $(command) - this notation can be nested!

/jan



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