Question

#!/usr/bin/perl

{
my $file = shift;                                                                     
print $file;
require $file;
}

run as ./arg /root/perl/arg getting:

Null filename used at /root/perl/arg line 13.
Compilation failed in require at ./arg line 6.

But the file actually exists,why ??

Answer 1

You have to call your program with one command-line argument:

./getting myfilename

Otherwise you’re trying to shift into a non-existent variable!

An alternative would be to refer to the argument directly and add a check:

my $num_args = $#ARGV + 1;

if ($num_args != 1)
{
  print "Error!";
  exit;
}

my $file = $ARGV[0];