Detecting control-c?

[William E. Rubin]

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.

 

[Daniel Berger]

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.

 

[Joe Van Dyk]

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.

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.

 

[Jim Freeze]

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?

 

[Joe Van Dyk]

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?

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

 

[gwtmp01]

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?

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.