loop with array in TCSH shell

Question

In TCSH :

I'm giving two lists containing different files in it. Then I have to pass those list as an array element and then the loop should execute twice as there are only 2 lists. But in this case loop is executing as much time as those files in both the lists.

set list_one = (one.s two.s three.s) set list_two = (four.s five.s) set arr=($list_one $list_two) foreach i ($arr) cat $i > $output.s end 

This is an example of my code, according to me loop should execute only twice(for list_one and list_two), but it's executing five times (for one.s two.s three.s four.s five.s)

Answer 1

The assignment set arr=($list_one $list_two) flattens the lists into one.

I'm not exactly sure what you're looking for here, but you could loop over the names of the lists with

set names=(list_one list_two) foreach i ($names) echo $i end 

But getting from there to actually using the first two lists after you have their name in a variable seems trickier. I can't find if tcsh supports indirect variable references, other than via eval. Something like this seems to work, but getting the quoting right on the eval seems fickly:

#!/usr/bin/tcsh set l1 = (aa bb cc) set l2 = (dd ee) set names = (l1 l2) foreach i ($names) eval set x = \(\$$i\) foreach j ($x) echo $i $j end end 

But it values containing whitespace get split, and I don't have an idea how to fix that.

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Honestly, I'd switch away from Tcsh, and do the same in e.g. Zsh :

l1=(aa bb cc) l2=(cc dd) names=(l1 l2) for i in $names; do for j in ${(P)i}; do echo $i $j done done 

That should deal with whitespace in the values, but does drop empty elements.