Logrotate fails if mysqld is not running (logrotate_script: 3: [: /var/run/mysqld/mysqld.pid: unexpected operator)

> Followup-For: Bug #830976

>

>

> I got  errors from cron:

>  /etc/cron.daily/logrotate:

>  logrotate_script: 3: [: /var/run/mysqld/mysqld.pid: unexpected operator

>

> The reason I found: The postrotate script of /etc/logrotate.d/mysql-server

> contains

>   my_print_defaults --mysqld | grep -oP "pid-file=\K[^$]+"

> and this generates on my machine two identical lines of output:

> /var/run/mysqld/mysqld.pid

> /var/run/mysqld/mysqld.pid

>

> So I added  " | uniq"  after the grep. Perhaps " | head -n1"

> would be even better.

I seems this was introduced in commit

https://anonscm.debian.org/cgit/pkg-mysql/mariadb-10.0.git/commit/debian/mariadb-server-10.0.mysql-server.logrotate?id=2948deb77b61f805e41b7032c71226a69d29a317

when importing upstream 10.0.25.

The original upstream commit that changed this was

https://github.com/MariaDB/server/commit/8942824a5304e23f765b88d07498786d80092843

I suggest you work directly with upstream to get this syntax fine

tuned and fixed globally.