How to call system having trap("CHLD", "IGNORE")?

Ruby
1

Hi all,

doing some forks I want to ignore SIGCHLD. But

trap(“CHLD”, “IGNORE”)
system “echo”

ends in ruby 1.8.2 (2005-04-11) [i386-linux] with a following error:

in `system’: no implicit conversion from nil to integer (TypeError)

Where I am wrong?

Thanks,

P.

2

On Tue, 18 Jul 2006, Pavel S. wrote:

Where I am wrong?

Thanks,

P.

it looks like a bug.

try

trap(‘SIGCHLD’){ nil }

-a

3

Hi,

In message “Re: How to call system having trap(“CHLD”, “IGNORE”)?”
on Tue, 18 Jul 2006 03:05:07 +0900, Pavel S. [email protected]
writes:

|doing some forks I want to ignore SIGCHLD. But
|
|trap(“CHLD”, “IGNORE”)
|system “echo”
|
|ends in ruby 1.8.2 (2005-04-11) [i386-linux] with a following error:
|
|in `system’: no implicit conversion from nil to integer (TypeError)
|
|Where I am wrong?

system() tried to pick up the exit status of forked sub-process.
Since you’ve set SIG_IGN sub-process disappeared without notice to
wait(2) system call, which failed and caused an error you’ve seen.
What did you try to accomplish by ignoring SIGCHLD?

It is fairly easy to make system to ignore wait(2) error, but I am not
sure it is the way to go.

						matz.
4

Hi,

In message “Re: How to call system having trap(“CHLD”, “IGNORE”)?”
on Tue, 18 Jul 2006 20:26:38 +0900, “Robert D.”
[email protected] writes:

|Hmm I conclude from your reply (and tested)
|trap(‘CHILD’, ‘IGNORE’) and
|trap(‘CHILD’){ nil }
|do not have the same semantics.

No they don’t. The former ignores SIGCHLD. The latter handles
SIGCHLD and invokes empty signal handler.

5

On 7/18/06, Yukihiro M. [email protected] wrote:

|system “echo”
What did you try to accomplish by ignoring SIGCHLD?

It is fairly easy to make system to ignore wait(2) error, but I am not
sure it is the way to go.

                                                    matz.

Hmm I conclude from your reply (and tested)
trap(‘CHILD’, ‘IGNORE’) and
trap(‘CHILD’){ nil }
do not have the same semantics.
Why should it be a bad idea to allow ignorining a Signal one can handle?

Just my 2**(-10) â?¬ :wink:

Robert

–
Deux choses sont infinies : l’univers et la bêtise humaine ; en ce qui
concerne l’univers, je n’en ai pas acquis la certitude absolue.

  • Albert Einstein