instance method

IO#pid

() -> ::Integer

pid → integer or nil

static VALUE
rb_io_pid(VALUE io)
{
    rb_io_t *fptr;

    GetOpenFile(io, fptr);
    if (!fptr->pid)
        return Qnil;
    return PIDT2NUM(fptr->pid);
}

Returns the process ID of a child process associated with the stream, which will have been set by IO#popen, or nil if the stream was not created by IO#popen:

Example

pipe = IO.popen("-")
if pipe
  $stderr.puts "In parent, child pid is #{pipe.pid}"
else
  $stderr.puts "In child, pid is #{$$}"
end

Output:

In child, pid is 26209
In parent, child pid is 26209

See also #pathconf #pos #path #pos= also in 4.1 · 3.4 · 3.3 · 3.2 · 3.1 · 3.0

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