comment on

I want to send a signal to a process group, but up-front I'd like to know if it has a chance of succeeding.

Background: perl abstracts the system call killpg() and warps it into kill() with negative signal numbers. So, if you call kill(-15, $pid), perl translates it to killpg(15, $pid) on systems that support killpg().

Problem is that in order to run killpg(0, $pid), I'd have to call kill(-0, $pid) which is the same as kill(0, $pid) and won't trigger the special killpg(0, $pid) behavior.

So, there's no way to check if a process is up but hasn't called POSIX::setsid() or POSIX::setpgid() yet, causing kill(15, $pid) to succeed but kill(-15, $pid) to fail.

Any way around that? I could roll my own killpg() XS module, but I'd rather have it portable across Unix flavors and, ideally, use something that already comes with perl.

In reply to Perl's kill(): How to check if process group exists? by saintmike

Are you posting in the right place? Check out Where do I post X? to know for sure.
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
Want more info? How to link or How to display code and escape characters are good places to start.


Your skill will accomplish what the force of many cannot
	PerlMonks