in reply to Variable expansion

Are you sure you're not literal quoting $cmd before putting it in the backticks? 
my $hr  = {foo => { bar => '/dev/null' } };

# will not work
my $cmd = 'ls $hr->{foo}->{bar}';
print `$cmd`;

# works a treat
my $cmd = "ls $hr->{foo}->{bar}";
print `$cmd`;

__output__

ls: -: No such file or directory
/dev/null

[download]

HTH

broquaint

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Re: Re: Variable expansion
by stephenpry (Initiate) on Apr 17, 2002 at 13:59 UTC
    I think the strings coming back are literals so what I must have is your case 1 which as you say doesn't work ! The literals contain strings that do map to local variables so somehow I've got to translate the part that is the variable to its value ? (I tried splitting it up where the '$' starts but when I set a new variable to: $newcmd=$cmd1.$cmd2; It seems to do the same thing.)
[reply]
      If you do have the unfortunate case of having the string not being interpolated then you could use the string version of eval() to get the desired result. 
      my $hr  = { foo => { bar => '/dev/null' } };
my $cmd_literal = 'ls $hr->{foo}->{bar}';
my $cmd = eval qq(return "$cmd_literal";);

print `$cmd`;

__output__

/dev/null

      [download]
      But the best option would be to have $cmd be interpolated rather than resorting to eval().
      HTH

      broquaint

[reply]
[d/l]
        Brilliant ! That works, thankyou.. I've struggled all morning with this (in Scotland ..)
[reply]

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