Perl simple command line args not being processed

Question

Consider this simple perl program:

#!/usr/bin/perl -s
print "ARGV: @ARGV\n";
print "arg: $arg\n";

Now run it:

chmod u+x test.pl
./test.pl -arg=works

The output is:

ARGV: 
arg: works

Running the program in the debugger works, too:

perl -d test.pl -arg=works

Loading DB routines from perl5db.pl version 1.53
Editor support available.

Enter h or 'h h' for help, or 'man perldebug' for more help.

main::(./test.pl:3):    print $arg, "\n";
  DB<1> c
ARGV:      <-- SEE HERE
arg: works <-- SEE HERE
Debugged program terminated.  Use q to quit or R to restart,
use o inhibit_exit to avoid stopping after program termination,
h q, h R or h o to get additional info.
  DB<1> q

However the argument will no longer be parsed if an include path is added:

perl -I . -d test.pl -arg works

Loading DB routines from perl5db.pl version 1.53
Editor support available.

Enter h or 'h h' for help, or 'man perldebug' for more help.

main::(./test.pl:3):    print $arg, "\n";
  DB<1> c
ARGV: test.pl -arg=works <-- OOPS
arg:                     <-- OOPS
Debugged program terminated.  Use q to quit or R to restart,
use o inhibit_exit to avoid stopping after program termination,
h q, h R or h o to get additional info.
  DB<1> q

When -I is used @ARGV does not seem to processed the same way. It is like the -s option no longer works as it is supposed to consume switches like -opt=value. Why is that?

Getopt::Long and Getopt::std both work just fine in all cases.

I thought for some time Perl extension in Visual Studio Code did not work correctly.

I can duplicate this behavior with perl -I . -d test.pl -arg works, but not with perl -I. -d test.pl -arg works (Note the lack of space between the -I and its argument). Odd. — Shawn
– Shawn, Commented Aug 8, 2021 at 4:49

ikegami · Accepted Answer · 2021-08-08 04:59:56Z

1

I can confirm that this is a bug. Reported.

Your test cases were quite poor, having lots of unnecessary and un-eliminated variables. So I'm going to do my own testing:

#!/usr/bin/perl -s
print "ARGV: @ARGV\n";
print "arg: $arg\n";
print @ARGV == 0 && $arg eq "test" ? "ok\n" : "XXX\n";

# Baseline
$ perl a.pl -arg=test
ARGV:
arg: test
ok

# With -I .
$ perl -I . a.pl -arg=test
ARGV: a.pl -arg=test
arg:
XXX

# The problem isn't the use of both -I and -s.
$ perl -I . -s a.pl -arg=test
ARGV:
arg: test
ok

# What about -w?
$ perl -w a.pl -arg=test
ARGV:
arg: test
ok

# Or -0?
$ perl -0777 a.pl -arg=test
ARGV:
arg: test
ok

# It's just -I
$ perl -CSDA a.pl -arg=test
ARGV:
arg: test
ok

$ perl -v | grep This
This is perl 5, version 34, subversion 0 (v5.34.0) built for x86_64-linux-thread-multi

This is a workaround:

$ perl -Mlib=. a.pl -arg=test
ARGV:
arg: test
ok

edited Aug 8, 2021 at 4:59

answered Aug 8, 2021 at 4:54

ikegami

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