ZSH for loop array variable issue

Question

I'm working in zsh, but I'm sure that bash instructions will also be helpful.

I need to have a for loop that goes through the values stored in the array lw and then launches a shell script, based on the name value stored in the array.

So far, this is what I've come up with:

$lw=('plugin1' 'plugin2' 'plugin3')

for i in $lw;
  do . ~/Library/Rogall/plugins/$lw[$i]/lw.prg end;
done

Running this gives me an error saying that it can't find ~/Library/Rogall/plugins//lw.prg. It appears as if it's ignoring my variable all together.

Any ideas where I've messed up?

Solution 1

It's actually much simpler than that:

lw=('plugin1' 'plugin2' 'plugin3')

for i in $lw; do
  . ~/Library/Rogall/plugins/$i/lw.prg end
done

In summary:

• Assign to foo, not $foo (the shell would try to expand $foo and assign to whatever it expands to; typically not useful)
• Use the loop variable directly; it contains the array value rather than the index

Solution 2

Why bother using the array? This can be done in portable sh very easily:

lw='plugin1 plugin2 plugin3'

for i in $lw;
  do . ~/Library/Rogall/plugins/$i/lw.prg end
done

Note that for this to work in zsh, you need to make zsh do the right thing with: set -o shwordsplit

Solution 3

I had a problem where a loop like this one

for i in (1 2 3 4); do echo $i; done

was repeatedly not working as I wanted. I would get errors like zsh: unknown file attribute: 1, or outputs like

1 2 3 4

no matter how I re-contorted it, instead of my desired

1
2
3
4

To get my desired behaviour I had to remove the in keyword from the loop definition

for i (1 2 3 4); do echo $i; done
1
2
3
4