Re: execline globbing

From: Laurent Bercot <>
Date: Tue, 24 Jul 2018 16:51:54 +0000

>elglob -0 fs somedir/*
>if { test -n $fs }
>ln -t otherdir $fs
>the test will fail if there’s more than one file in `somedir`.
>Is there a way to put a split variable into one variable again?

  Your next door "echo" command will do just that (or s6-echo
if you risk having dashes and want reliable behaviour in all cases).

elglob -0 splitfs somedir/*
backtick -n fs { echo $splitfs }
importas -u fs fs
if { test -n $fs } ...

>It feels kind of clumsy to use elglob, especially because of
>the default verbatim input of the pattern if no expansion is
>found. I can’t imagine any use case where I’d want that,
>especially not as default behaviour.

  The shell has the exact same default behaviour. I didn't want to
gratuitously diverge from the shell. But I agree "elglob -0" is the
behaviour you want most of the time.

>Another fun effect:
>>execlineb -c 'elglob -0 f doesnotexist/* if { test -z "${f}" } echo
>>execlineb -c 'elglob -0 f doesnotexist/* if { test -n "${f}" } echo
>So for `test`, the ominous “zero string” of execline is both
>empty and non-empty!
>Is there some elaboration somewhere what this zero string is?
>And how do work with it?

  It's not a "zero string". It's zero word. Which means the "${f}"
argument is replaced with nothing at all, not even an empty string.
So the tests resolve to:
test -z
test -n
which both return true.

Received on Tue Jul 24 2018 - 16:51:54 UTC

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