How to Keep a MySQL Connection Open in Bash

Question

I have a bash script that calls MySQL several times. Instead of having to reconnect to MySQL, is there a way to keep the connection open? Ideally, the connection would close if the script exits early. I'm thinking named pipes would work but they would stay open.

Here's a quick pseudo-example of what I hope to find:

openMySQL
executeMySQL "SELECT 1"
exit 1
executeMySQL "SELECT 2"

I'm looking for the openMySQL and executeMySQL functions where the MySQL connection will actually close during the exit 1.

Answer 1

To the best of my understanding your question: coproc's available in zsh/ksh and also bash v4+ might be similar to what you have in mind, e.g.

bash4-4.1$ coproc MYSQL mysql -B -uroot 
[1] 10603
bash4-4.1$ jobs
[1]+  Running                 coproc COPROC MYSQL mysql -B -uroot &
bash4-4.1$ echo 'show databases;' | MYSQL
Database
information_schema
...

The command is kept running in the background, its stdin/stdout can accessed, it will finish (as a result its standard input closing/*EOF*ing) as soon as the current shell exists...