System ( ) call but suppressing =>true

ruby-talk
1

I have a Perl script that takes a command line argument that I'm trying
call from a Ruby (in Rails).

The Perl script needs an IP address on the command line and runs as
follows:

/usr/bin/router.pl 172.21.1.1

The following ruby code works perfectly for what I want but the only
problem is that it returns "=>true" in addition to my data.

I tried formulating a string and putting backquotes on it but couldn't
get that to work. (example `x + y + z`)

Is there any way to make system() suppress =>true?

x = "/usr/bin/router.pl"
y = " "
z = "172.21.1.1"
system(x + y + z)

thanks again...

jackster

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2

jackster the jackle wrote:

Is there any way to make system() suppress =>true?

x = "/usr/bin/router.pl"
y = " "
z = "172.21.1.1"
system(x + y + z)

thanks again...

jackster

You're trying this out in irb, aren't you? All you're seeing is irb printing the return value from system() so you can see what it returned. The system method doesn't really add "=>true" to the output from the command.

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3

jackster the jackle wrote:

The following ruby code works perfectly for what I want but the only
problem is that it returns "=>true" in addition to my data.

I tried formulating a string and putting backquotes on it but couldn't
get that to work. (example `x + y + z`)

The Kernel#system method returns a boolean datatype, that is -- true if
the command was ran sucessfully, false otherwise.

Use backticks or %x{} is you want to store the output

var = `#{ foo + bar + baz}` # as Marc said
var = %x{ #{foo + bar + baz} } # Im pretty sure that works, sorry I
can't test it right now.

HTH

Regards,
Lee

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4

Instead of

  system(x + y + z)

you could always use backticks and assign to a var (I think it is
Kernel#`)

  var = `#{x+y+z}`

or just use systemu and select what output is used.

  http://codeforpeople.com/lib/ruby/systemu/

  require 'systemu'
  status, stdout, stderr = systemu 'configure' # if you have a configure
script
  p [ status, stdout, stderr ] # just select what to feedback the user

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5

Thanks alot Marc....I used var = `#{x+y+z}` and it worked perfectly.

jackster

Marc Heiler wrote:

···

Instead of

  system(x + y + z)

you could always use backticks and assign to a var (I think it is
Kernel#`)

  var = `#{x+y+z}`

or just use systemu and select what output is used.

  http://codeforpeople.com/lib/ruby/systemu/

  require 'systemu'
  status, stdout, stderr = systemu 'configure' # if you have a configure
script
  p [ status, stdout, stderr ] # just select what to feedback the user

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6

fr your op, y is a space, so you may lose it, and do

var = `#{x} #{z}`

or

x << " " << z
var = `#{x}`

or

system x,z

kind regards -botp

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On Dec 19, 2007 10:49 PM, jackster the jackle <contact@thirdorder.net> wrote:

Thanks alot Marc....I used var = `#{x+y+z}` and it worked perfectly.