Job control (stop/continue, a.k.a. suspend/resume) does not work

[cedric-vincent]

How to reproduce:

$ proot bash
$ emacs
^Z
[1]+  Stopped                 emacs

Expected behavior: emacs is stopped.

Actual behavior: emacs still runs.

[cedric-vincent]

As of my understanding, this is supported only since Linux 3.4. Here is a quote from ptrace man-page:

PTRACE_LISTEN (since Linux 3.4)

Restart the stopped tracee, but prevent it from executing. The resulting state of the tracee is similar to a process which has been stopped by a SIGSTOP (or other stopping signal). See the "group-stop" subsection for additional information. PTRACE_LISTEN works only on tracees attached by PTRACE_SEIZE.