sorry, dumb question possibly, I just want to make sure. if I call
some Unix command using backticks, that invokes the command, launches
a new process, and waits until that process terminates before resuming
program execution, right? especially if I do this:
shell_output = `some process`
which should capture the output of the process. right? it isn't possible to say
shell_output = `some process`
and accidentally see execution fork, is it?
--
Giles Bowkett
http://www.gilesgoatboy.org
sorry, dumb question possibly, I just want to make sure. if I call
some Unix command using backticks, that invokes the command, launches
a new process, and waits until that process terminates before resuming
program execution, right? especially if I do this:shell_output = `some process`
which should capture the output of the process. right? it isn't possible to
sayshell_output = `some process`
and accidentally see execution fork, is it?
Right, ruby will wait for the process to complete.
On Mon, Nov 20, 2006 at 08:05:45AM +0900, Giles Bowkett wrote:
--
Giles Bowkett
http://www.gilesgoatboy.org
Giles Bowkett wrote:
sorry, dumb question possibly, I just want to make sure. if I call
some Unix command using backticks, that invokes the command, launches
a new process, and waits until that process terminates before resuming
program execution, right? especially if I do this:shell_output = `some process`
which should capture the output of the process. right? it isn't possible
to sayshell_output = `some process`
and accidentally see execution fork, is it?
That depends on what you put between the back-ticks.
This:
`command > /dev/null &`
will almost certainly fork. There are any number of forking contingencies,
depending on what you try to run, and how.
--
Paul Lutus
http://www.arachnoid.com
Sorry, reading this email reminded me of my project. Say I wanted to do a
bunch of pings using backticks (you may have asked my stupid n00b questin
about ``). If I wanted to do a bunch of pings, which would take some small
amount of time, would it be better(faster) to start new threads before doing
the `ping whatever`, or is there a better/different way?
On 11/19/06, Paul Lutus <nospam@nosite.zzz> wrote:
Giles Bowkett wrote:
> sorry, dumb question possibly, I just want to make sure. if I call
> some Unix command using backticks, that invokes the command, launches
> a new process, and waits until that process terminates before resuming
> program execution, right? especially if I do this:
>
> shell_output = `some process`
>
> which should capture the output of the process. right? it isn't possible
> to say
>
> shell_output = `some process`
>
> and accidentally see execution fork, is it?That depends on what you put between the back-ticks.
This:
`command > /dev/null &`
will almost certainly fork. There are any number of forking contingencies,
depending on what you try to run, and how.--
Paul Lutus
http://www.arachnoid.com
That depends on what you put between the back-ticks.
This:
`command > /dev/null &`
will almost certainly fork. There are any number of forking contingencies,
depending on what you try to run, and how.
well, that's probably it. the command I'm using is a very long,
involved command to a complex utility that handles media files, and
apparently takes an infinite number of command-line arguments, but the
final args are "2>&1". I inherited this code, as I understand it that
just pipes standard error and standard out to the same place --
however, now I think that might be what's going wrong.
--
Giles Bowkett
http://www.gilesgoatboy.org
Jason Mayer wrote:
Sorry, reading this email reminded me of my project. Say I wanted to do a
bunch of pings using backticks (you may have asked my stupid n00b questin
about ``). If I wanted to do a bunch of pings, which would take some small
amount of time, would it be better(faster) to start new threads before doing
the `ping whatever`, or is there a better/different way?
Sure, why not use threads:
t0 = Time.now
threads = (1..10).map do |i|
Thread.new do
addr = "192.168.0.#{i}"
[addr, `ping -w3 -nq #{addr}`]
end
end
values = threads.map {|thread| thread.value}
t1 = Time.now
puts "Finished in #{t1 - t0} seconds"
require 'yaml'
y values.select {|addr, out| out !~ / 0 received/}
__END__
Output:
Finished in 3.011614 seconds
---
- - 192.168.0.1
- |
PING 192.168.0.1 (192.168.0.1) 56(84) bytes of data.
--- 192.168.0.1 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2001ms
rtt min/avg/max/mdev = 2.032/3.052/4.750/1.210 ms
...
--
vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407
ok never mind about that last post. it does appear to be pipe commands
for standard out and standard err and that shouldn't result in
backgrounding.
On 11/19/06, Giles Bowkett <gilesb@gmail.com> wrote:
> That depends on what you put between the back-ticks.
>
> This:
>
> `command > /dev/null &`
>
> will almost certainly fork. There are any number of forking contingencies,
> depending on what you try to run, and how.well, that's probably it. the command I'm using is a very long,
involved command to a complex utility that handles media files, and
apparently takes an infinite number of command-line arguments, but the
final args are "2>&1". I inherited this code, as I understand it that
just pipes standard error and standard out to the same place --
however, now I think that might be what's going wrong.--
Giles Bowkett
http://www.gilesgoatboy.org
--
Giles Bowkett
http://www.gilesgoatboy.org