As it is "eval" won't help you avoid this problem, but in fact make it worse. Without "eval" your command line becomes interpreted by the shell once, with it twice. I don't think "eval" should be avoided generally (like you seem to believe Corona688 is thinking), but in this case it is simply the wrong tool - and probably very dangerous, as Corona688 pointed out correctly.

If you want to avoid interpretation of a certain string use quotation - that is, what it is for. For intance:

Code:

exclude="*.txt"

$ echo $exclude
a.txt b.txt c.txt
$ echo "$exclude"
*.txt
$ echo '$exclude'
$exclude

Now, let us apply this to your problem. I use ":" as a delimiter here, like in the PATH variable, because commas or something such could be used in filenames and i want to avoid that:

Code:

#! /bin/ksh

excludelist="foo:*.bar:baz.*"

exclude=""

while [ -n "$excludelist" ] ; do
     exclude="$exclude --exclude \"${excludelist%%:*}\""
     if [ "${excludelist%%:*}" = "${excludelist}" ] ; then
          excludelist=""
     else
          excludelist="${excludelist#*:}"
     fi
     # this is just to show how it works, can be removed:
     print - "excludelist: \"$excludelist\" args to tar: \"$exclude\""
done

tar <options> $exclude <more options>

I would like to say for the record, that i don't think the contents of the variable excludelist should be modified by modifying the scripts text at all. Instead a configuration file should be passed to the script, which contains all the exclusions. How to construct a syntax for such a configuration file and how to parse it i have described here, but the way of feeding the options to tar will still be as lain out here.

I hope this helps.

bakunin