stdlib_libraries/process_identity_no_parens.rb

tests/_examples/stdlib_libraries/process_identity_no_parens.rb in the metorex repository.

# What a process reports about itself: the groups and sessions it belongs to,
# the scheduling it runs under, and the ids it runs as.
p Process.getpgrp == Process.getpgid(0)
p Process.getsid == Process.getsid(0)
p Process.getpriority(Process::PRIO_PROCESS, 0).is_a?(Integer)
p Process.times.is_a?(Process::Tms)
p Process.times.utime.is_a?(Float)

# The same ids go by more than one name.
p Process::UID.rid == Process.uid
p Process::GID.rid == Process.gid
p Process::Sys.getuid == Process.uid
p Process::Sys.getegid == Process.egid

# The constants the operating system names its settings by.
p [Process::WNOHANG, Process::WUNTRACED].all? { |held| held.is_a?(Integer) }
p [Process::PRIO_PROCESS, Process::PRIO_PGRP, Process::PRIO_USER].uniq.length
p Process::RLIMIT_NOFILE.is_a?(Integer)

# Renaming the process leaves `$0` alone, and `_fork` splits the process,
# answering 0 in the child.
p Process.setproctitle("metorex-example")
child = Process._fork
Process.exit! 0 if child == 0
p Process.wait2(child)[1].exitstatus

# A signal sent to a process that is not there is refused.
begin
  Process.kill :TERM, 999_999
rescue Errno::ESRCH => problem
  p(problem.class)
end

# Setting a group list without the right to do so is refused too.
begin
  Process.groups = [0]
rescue Errno::EPERM => problem
  p(problem.class)
end

Output:

true
true
true
true
true
true
true
true
true
true
3
true
"metorex-example"
0
Errno::ESRCH
Errno::EPERM