在Bash脚本中使用＆内部脚本有不利之处吗？

Question

I am making a script that should install MariaDB/MySQL server and then create users and such. For this I need mysqld_safe to be running, which doesn't have a daemon mode, so the script won't continue. Doing mysqld_safe & works it seams.

/usr/bin/mysqld_safe > /dev/null 2>&1 &

RET=1
while [[ RET -ne 0 ]]; do
    sleep 5
    mysql -uroot -e "status" > /dev/null 2>&1
    RET=$?
done

...

Question

Are there downsides, or is it bad practice, to use & inside bash scripts?

If, what is the recommended method?

Answer 1

You want a negative answer, but I do this also to improve a stability of my script in raspberry.

I also store PID of the process so that I could kill it later in the script.

I use lockfile, and I check the existence of the 'mysql_safe' before running it.

However, I cannot comment on if it is a good practice.

Answer 2

I don't think you have any alternative to & if you need to run several processes in parallel, and it looks like you really do.

Running several parallel processes without good reason exposes you to all kinds of race conditions and therefore should be avoided, hence the general advice not to use & thoughtlessly in your scripts.

I just hope you didn't forget to terminate the mysqld_safe process at the end of your script.