Problem:
==============
By testing `pgrep` with `--ns` option,
introduced with MDEV-21331, commit fb7c1b9415,
I noted that:
a) `--ns` cannot use more than single PID.
b) `--ns` is returning the processes of the namespace to which supplied PID belongs to.
So by that sense command `pgrep -x --ns $$ mysqld` will always return an error and skip
checking of the existing PID of the server.
Solution:
==============
Suggested solution is to add `--nslist pid`, since `--ns` needs to know in which namespace type it should look for.
See `pgrep --help` for different namespace types.
Note also that this works *only* if script is run as a `root` (we have that case here).
Current PR is a part of:
1. MDEV-21331: sync preinst and postrm script
2. MDEV-15718: check for exact mysqld process
This commit:
a) fixes fb7c1b9415
b) Closes PR #2068 (obsolete)
c) Closes PR #2069 (obsolete)
Thanks Faustin Lammler <faustin@mariadb.org> for testing and verifying
Reviewed by <>
