Detecting control-c?

ruby-talk
1

How does one detect Control-C?

I know that it raises an Interrupt, but there are other things that are
also Interrupts (such as Timeout::Error). The documentation at
ruby-doc.org doesn't list any details of class Interrupt, and the
"Programming Ruby" book at ruby-lang.org doesn't even seem to mention
that class Interrupt exists.

Thanks.

2

William E. Rubin wrote:

How does one detect Control-C?

trap("INT"){ ... }

I know that it raises an Interrupt, but there are other things that are
also Interrupts (such as Timeout::Error). The documentation at
ruby-doc.org doesn't list any details of class Interrupt, and the
"Programming Ruby" book at ruby-lang.org doesn't even seem to mention
that class Interrupt exists.

Thanks.

Interrupt is a subclass of SignalException (which is a subclass of Exception). As far as I can tell (based on what I see in eval.c) it's only used for trapping Unix signals*, i.e. whatever's in your signal.h file.

Also, take a look at the Signal module.

Regards,

Dan

* Works on Windows too, though the implementation is different, and likely requires a separate sleeper thread.

3

hump::/home/mz652c% cat signal.rb

trap("INT") do
  puts "got signal INT"
end

puts "Sup"
gets

hump::/home/mz652c% ruby signal.rb
Sup
got signal INT
got signal INT
got signal INT
got signal INT
got signal INT

pressing ctrl-c generates 'got signal INT'. Had to press ctrl-d to
exit the program.

···

On 12/8/05, William E. Rubin <williamerubin@dodgeit.com> wrote:

How does one detect Control-C?

I know that it raises an Interrupt, but there are other things that are
also Interrupts (such as Timeout::Error). The documentation at
ruby-doc.org doesn't list any details of class Interrupt, and the
"Programming Ruby" book at ruby-lang.org doesn't even seem to mention
that class Interrupt exists.

4

Interesting. When I ran the program above I get:
^Cgot signal INT
....

Any ideas on how to not get the '^C' text?

···

On 12/8/05, Joe Van Dyk <joevandyk@gmail.com> wrote:

trap("INT") do
  puts "got signal INT"
end

puts "Sup"
gets

hump::/home/mz652c% ruby signal.rb
Sup
got signal INT
got signal INT

--
Jim Freeze

5

Dunno, I didn't get the '^C' text. (on linux)

···

On 12/9/05, Jim Freeze <jim@freeze.org> wrote:

On 12/8/05, Joe Van Dyk <joevandyk@gmail.com> wrote:
> trap("INT") do
> puts "got signal INT"
> end
>
> puts "Sup"
> gets
>
> hump::/home/mz652c% ruby signal.rb
> Sup
> got signal INT
> got signal INT

Interesting. When I ran the program above I get:
^Cgot signal INT
....

Any ideas on how to not get the '^C' text?

6

The ^C is your ctrl-c being echoed by the
terminal device driver. You can use the stty
program to alter the behavior of the tty driver.
In particular, take a look at the -echoctl
option. In any case, the foreground process (ruby) doesn't
see the ctrl-c because the tty driver discards
it and sends the Interrupt signal instead and then takes
car of echoing '^C' back to the terminal itself.

The specific behavior may also depend on the particular
shell you are using.

Hope this helps.

···

On Dec 9, 2005, at 8:50 AM, Jim Freeze wrote:

On 12/8/05, Joe Van Dyk <joevandyk@gmail.com> wrote:

trap("INT") do
  puts "got signal INT"
end

puts "Sup"
gets

hump::/home/mz652c% ruby signal.rb
Sup
got signal INT

Interesting. When I ran the program above I get:
^Cgot signal INT
....

Any ideas on how to not get the '^C' text?