Re^2: Indirect variable expansion

Don't use this code, the correct $M is only visible inside the subprocess, hence the use has to happen inside.

FWIW: you don't need to export explicitly if you use this special bash syntax. Note the missing ;

~$ M="Data::Dumper" perl -M$M -E'say $ENV{M}->VERSION'
2.188
[download]

Furthermore, -M doesn't seem to throw an error for unknown modules.

So adding warnings -w to your execution will help you catch typos

~$ M="Data::Dumb" perl -M$M -wE'say $ENV{M}->VERSION'
Use of uninitialized value in say at -e line 1.
[download]

Cheers Rolf
_{(addicted to the Perl Programming Language :)

see Wikisyntax for the Monastery}

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Re^3: Indirect variable expansion by etj (Priest) on Nov 18, 2024 at 12:55 UTC
Furthermore, -M doesn't seem to throw an error for unknown modules. Yes, it does: `perl -MNotRight -e 0 Can't locate NotRight.pm in @INC (you may need to install the NotRight + module) (@INC contains: ...` [download]	[reply] [d/l]
Re^4: Indirect variable expansion by LanX (Saint) on Nov 18, 2024 at 14:57 UTC
> Yes, it does: Well obviously not for me and the code I posted! update the problem seems to be bash related, the `-M$M` doesn't expand the $M I've just set. But Perl's sub-process has the correct ENV. Cheers Rolf _{(addicted to the Perl Programming Language :) see Wikisyntax for the Monastery}	[reply] [d/l]
Re^5: Indirect variable expansion by hippo (Archbishop) on Nov 18, 2024 at 15:41 UTC
Well, yes. At the time the variable substitution occurs, the variable has not been set yet. eg.: `$ quux=foo echo $quux $` [download] "Fix" it by separating the one command into 2: `$ quux=foo; echo $quux foo $` [download] It isn't just bash, BTW. Any Bourne-compatible shell should behave like this. 🦛	[reply] [d/l] [select]
Re^6: Indirect variable expansion by jeffenstein (Hermit) on Nov 18, 2024 at 16:10 UTC
Re^7: Indirect variable expansion by LanX (Saint) on Nov 18, 2024 at 16:35 UTC