How do I keep the command line from eating the backslashes?

[Anonymous Monk]

Silly easy novice question: How do I preserve \" passed in on the commandline?
i.e: foo.pl -bar=\"donteatem\"
I get $ARGV[0] as -bar="donteatem", where i really do want to keep the backslashes.

Thanks in advance.

20050212 Edit by castaway: Changed title from 'Easy @ARGV question'

[amw1]

assuming bash or similar shell (unknown on windows)

# \\ escapes the slash
# \" escapes the quote
# so \\\" escapes a single slash and a quote
foo.pl -bar=\\\"donteatem\\\"

perl should get -bar=\"donteatem\"

[Anonymous Monk]

Ahh... I'd love to be able to do that... But what if I cannot control the input? I'm reading input destined for another program, and I (most unfortunately) don't have control of what's generating the commandline.

So, I'm always going to get \" instead of \\"

[VSarkiss]

You just answered your own question: if you don't have control over the input, then you can't change what you get. Whether the program gets passed the backslashes on the command line depends on the command processor, not Perl. Your program can only work with what it's given.

[sgifford]

Two thoughts.

First, it's the shell that's eating the quotes and backslashes. If you change the shell to a program of your own, you can process these characters however you want. Many programs use the SHELL environment variable to select the shell to run, so changing that might help.

Second, in order for arguments to have gotten through the shell, they must have been quoted properly. quotemeta can quote them properly, even if it's not the same way they were originally quoted.

[artist]

Apply Escape char '\' to both of them.


$a = qq(\\\"hello world\\\");
print $a;

gives

 \"hello world\"

[sh1tn]

assuming the ugly win32 cli:


program.pl "\"argument\""

[revdiablo]

This feels like an XY problem. You're trying to do X, and you thought of solution Y. So you're asking about solution Y, without even mentioning X [your later posts hint at X, but never really describe it]. The problem is, there might be a better solution, but we can't know that unless you describe what X is.

In other words, I would be surprised if you really need the literal '\"' to remain intact. What is the actual problem you're trying to solve?

[ikegami]

In Windows,
>perl -e "print $ARGV[0]" "test"
test
>perl -e "print $ARGV[0]" \"test\"
"test"
>perl -e "print $ARGV[0]" "\"test\""
"test"

Ug, this is very broken:
>perl -e "print $ARGV[0]" "te\st"
te\st
>perl -e "print $ARGV[0]" "te\\st"
te\\st
>perl -e "print $ARGV[0]" "te\"st"
te"st
>perl -e "print $ARGV[0]" "te\\"st"
te\st

Alternate (older?) quoting mechanism:
>perl -e "print $ARGV[0]" """test"""
"test"
>perl -e "print $ARGV[0]" """Nevermore"""", quoted the raven."
"Nevermore", quoted the raven.

[DrHyde]

You start by asking on shellmonks instead of perlmonks.