ACI has asked for the wisdom of the Perl Monks concerning the following question:

Hi there. This is infuriating me and I can't comprehend why it's happening. Best guess is that I've mangled the perl folder somehow. But re-installing the OS (Ubuntu Linux) doesn't help. Have I disabled something? Can I debug somehow? How can I find out why this is suddenly not working? Any assistance deeply appreciated!

File: 'test.pl' 

print "Hello world!\n";
do 'test-response.pl';
print "Did that work?";

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File: 'test-response.pl' (same directory as 'test.pl') 
print "Hello Andy!\n";

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Output: 
Hello world!
Did that work?

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Couldn't be simpler, surely? Done this a million times and never had a problem (unless my code has errors, which is not the problem here).

Thanks in advance!

Andy

Replies are listed 'Best First'.
Re: 'do' command is dead? Surely not?
by haukex (Archbishop) on May 19, 2017 at 14:00 UTC

    You may want to try adding the error checking from the do docs:

    unless (my $return = do $file) {
    warn "couldn't parse $file: $@" if $@;
    warn "couldn't do $file: $!"    unless defined $return;
    warn "couldn't run $file"       unless $return;
}

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    Update: Oh, and of course Use strict and warnings.

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      Thanks haukex - swift reply!

      What, me, not using strict and warnings? ;-) Have changed 'test.pl' to the following:

      use strict;
use warnings;

print "Hello world!\n";

my $file='test-response.pl';

unless (my $return = do $file) {
    warn "couldn't parse $file: $@" if $@;
    warn "couldn't do $file: $!"    unless defined $return;
    warn "couldn't run $file"       unless $return;
}

print "Did that work?\n";

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      Output is now

      Hello world!
couldn't do test-response.pl: No such file or directory at test.pl lin
+e 10.
couldn't run test-response.pl at test.pl line 11.
Did that work?

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      The file 'test-response.pl' is certainly there.... (the files are on my desktop and I'm calling them from a command prompt having changed directory to the desktop, by the way).

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        You can check perl's current directory with Cwd (no matter how unlikely it seems for something to be the cause of a defect, if you're stuck, it's better to check than "just know"). You can also check which files .pl perl sees in the current folder with: 

        use Data::Dump qw( pp );
pp <*.pl>;

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        I used Data::Dump instead of a simple print, because it will explicitly display characters that might go otherwise unnoticed. If you don't want to install it, you can use Data::Dumper and set $Data::Dumper::Useqq to 1

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[d/l]
        do docs say "searches the @INC", so maybe check if "." is missing.
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        The file 'test-response.pl' is certainly there...

        Not to Perl it seems... I would investigate this further. For example, try things like print -e $file ? "exists\n" : "doesn't exist\n";, use Cwd; print getcwd, "\n";, or my $file='/absolute/path/to/test-response.pl';. Also, what version of Perl are you using?

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