Problem with `arp -a`

Hi everyone.

I have a problem with this command:

@arp_table = `arp -n`

When I execute it on console, all is perfect, but when I put it in the
script on Rails the string arp_table is empty and I don't view any
result.

If I do a script like that:

@list = `ls -l`

all works perfectly.

Where is the mistake ?

Thanks in advance

Misha Mistral wrote:

Hi everyone.

I have a problem with this command:

@arp_table = `arp -n`

When I execute it on console, all is perfect,

Are you passing arp any other arguments? On OS X, arp -n just prints a
help message to stderr.

but when I put it in the
script on Rails the string arp_table is empty and I don't view any
result.

If I do a script like that:

@list = `ls -l`

all works perfectly.

Where is the mistake ?
  
If arp -n may be printing to stderr, rather than stdout. Try:

@arp_table = `arp -n 2>&1`

Quoting Misha Mistral <rails-mailing-list@andreas-s.net>:

Hi everyone.

I have a problem with this command:

@arp_table = `arp -n`

When I execute it on console, all is perfect, but when I put it in the
script on Rails the string arp_table is empty and I don't view any
result.

What user is the command running as? On my system (OpenSuSE 10.3) arp is in
/sbin, i.e., root only.

Jeffrey