Backup Script, Stored Procedure check

[Gary Ikeda]

I'm writing a backup stored procedure to work hand in hand with a shell script:

1) Launch shell script
2) Shell script forks mysql command which executes stored procedure
3) Stored procedure flushes cache and sets database read only
3) Shell script pauses then attempts to copy mysql data files
4) mysql stored procedure waits in loop for signal from the OS copy to notify it's done copying
5) mysql stored procedure exits loop and unlocks database as readwrite

The issue I'm having is trying to check from the stored procedure loop, read a flag from the shell. I was thinking if mysql can read environment variables, I can set them to new values within the shell script, when the value changes, we have a signal. Either that or if mysql could see if a file exists, I can do a "touch" at the end of the shell copy to create a file which mysql will see, signaling to exit the stored procedure wait loop.

The reason I'm posting this is I don't see a way for mysql to see a file or environment variable value. Is there any way to signal the stored procedure that the shell copy is done?

Thank you in advance.

Gary