[ILUG] Avoiding password on mysqldump command line

[Kenn Humborg]

I want to backup a MySQL database.  So, I'll be creating
a backup user that has global SELECT permission and whatever
else is needed to run

   mysqldump -u backup -p=BLAH --all-databases --opt > dump.sql

However, how do I avoid putting the password on the command line
where it will be visible to anyone running ps awx?

I've tried 

   echo BLAH | mysqldump -u backup -p --all-databases ...

and 

   mysqldump -u backup -p --all-databases ... <<EOF
   BLAH
   EOF

But neither works.  It seems mysqldump wants to read from the "tty",
not from stdin.

Later,
Kenn