How to not display output of a system call

ruby-talk
1

Lets say I have a Windows command line program that runs the following:

system("del *.txt")

How do I NOT display the output from the del command?

Thank you.

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2

Also, how do you make the program pause for a few seconds.

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3

In this case:

Dir["*.txt"].each {|f| File.delete f}

:slight_smile:

  robert

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On 10/06/2009 10:29 PM, Jerry Mr wrote:

Lets say I have a Windows command line program that runs the following:

system("del *.txt")

How do I NOT display the output from the del command?

Thank you.

--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

4

Jerry Mr wrote:

Lets say I have a Windows command line program that runs the following:

system("del *.txt")

How do I NOT display the output from the del command?

Thank you.

`del *.txt`

That's backticks, not apostrophes. Also, this won't prevent the display of output to stderr, only stdout.

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5

Jerry Piazza wrote:

Lets say I have a Windows command line program that runs the following:

system("del *.txt")

How do I NOT display the output from the del command?

You could try something like this:

  system("del *.txt >NUL")

Otherwise try IO.popen, which can capture the output of the command, so
you can throw it away.

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6

Put it to SLEEP.

  robert

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On 10/06/2009 10:45 PM, Jerry Mr wrote:

Also, how do you make the program pause for a few seconds.

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remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

7

Jerry Mr wrote:

Also, how do you make the program pause for a few seconds.

$ ri Kernel#sleep
----------------------------------------------------------- Kernel#sleep
      sleep([duration]) => fixnum

      From Ruby 1.9.1

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------------------------------------------------------------------------
      Suspends the current thread for duration seconds (which may be any
      number, including a Float with fractional seconds). Returns the
      actual number of seconds slept (rounded), which may be less than
      that asked for if another thread calls Thread#run. Zero arguments
      causes sleep to sleep forever.

         Time.new #=> 2008-03-08 19:56:19 +0900
         sleep 1.2 #=> 1
         Time.new #=> 2008-03-08 19:56:20 +0900
         sleep 1.9 #=> 2
         Time.new #=> 2008-03-08 19:56:22 +0900

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8

Tim Hunter wrote:

`del *.txt`

That's backticks, not apostrophes. Also, this won't prevent the display
of output to stderr, only stdout.

Hrmm, backticks don't seem to work on windows boxes.

Tries to point to a CMD variable instead.

@Robert Klemme

I agree that doing it entirely in ruby would be the better way to go
about it.
Just sometimes it is quicker to use a command that is already available
(or run a utility I added to %path%) to speed things up at work.

Plus, now that I am wondering, it will haunt me until I find the answer.

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9

I am now trying to impliment this.

I created this:
def spinner spin_trigger
while (spin_trigger == true)
  print "\\\r"
  sleep 1
  print "|\r"
  sleep 1
  print "/\r"
  sleep 1
  print "-\r"
  sleep 1
end
end

spin = true
Thread.new do
  spinner spin
end
files = Dir.glob("c:/**/*.txt")
spin = false

But all I get is a "\" stuck at the beginning of the line until the Dir
command finishes.

Maybe I am confused about the usage of Thread?

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10

Jerry Piazza wrote:

I am now trying to impliment this.

I created this:
def spinner spin_trigger
while (spin_trigger == true)
  print "\\\r"
  sleep 1
  print "|\r"
  sleep 1
  print "/\r"
  sleep 1
  print "-\r"
  sleep 1
end
end

spin = true
Thread.new do
  spinner spin
end
files = Dir.glob("c:/**/*.txt")
spin = false

But all I get is a "\" stuck at the beginning of the line until the Dir
command finishes.

Maybe I am confused about the usage of Thread?

I think you have some more basic issues to deal with first. What do you
think the output of the following code will be:

def test(x)
  while x == 20
    sleep 3
    puts x
  end
end

x = 10
test(20)
x = 30

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11

Jerry Piazza wrote:

I am now trying to impliment this.

I created this:
def spinner spin_trigger
while (spin_trigger == true)

Comparing with "true" or "false" to obtain a boolean value is a very bad idea - especially in Ruby which has two false values and unlimited true values.

  print "\\\r"
  sleep 1
  print "|\r"
  sleep 1
  print "/\r"
  sleep 1
  print "-\r"
  sleep 1
end
end

spin = true
Thread.new do
  spinner spin
end
files = Dir.glob("c:/**/*.txt")
spin = false

But all I get is a "\" stuck at the beginning of the line until the Dir command finishes.

Maybe I am confused about the usage of Thread?

I think you have some more basic issues to deal with first. What do you think the output of the following code will be:

def test(x)
  while x == 20
    sleep 3
    puts x
  end
end

x = 10
test(20)
x = 30

Absolutely!

  robert

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On 07.10.2009 04:58, 7stud -- wrote:

--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/