diff --git a/perl/content.md b/perl/content.md index 9b9c3d5fd..bbaa6841c 100644 --- a/perl/content.md +++ b/perl/content.md @@ -49,10 +49,10 @@ $ docker exec sleeping_beauty kill 1 will *not* stop the perl running on the `sleeping_beauty` container (it will keep running until the `sleep 300` finishes.) To do so, one must set a signal handler like this: ```console -$ docker run -it --name quick_nap --rm %%IMAGE%%:5.20 perl -E '$SIG{TERM} = sub { say "recv TERM" }; sleep 300' +$ docker run -it --name quick_nap --rm %%IMAGE%%:5.20 perl -E '$SIG{TERM} = sub { $sig++; say "recv TERM" }; sleep 300; say "waking up" if $sig' ``` -so doing `docker exec quick_nap kill 1` (or the simpler `docker stop quick_nap`) will immediately stop the container, and print `recv TERM` in the other terminal. +so doing `docker exec quick_nap kill 1` (or the simpler `docker stop quick_nap`) will immediately stop the container, and print `recv TERM` in the other terminal. Note that the signal handler does not stop the perl process itself unless it calls a `die` or `exit`; in this case, perl will continue and print `waking up` *after* it receives the signal. If your Perl program is expected to handle signals and fork child processes, it is encouraged to use an init-like program for ENTRYPOINT, such as [dumb-init](https://github.com/Yelp/dumb-init) or [tini](https://github.com/krallin/tini) (the latter is available since Docker 1.13 via the `docker run --init` flag.)