The Unix utility you never knew you needed until you needed it! await
simply waits for any signal to be delivered to its process using the
sigwait system call. Use it in bash scripts to avoid needing to create
a spin lock or dummy file.
There is no timeout, nor are there any command line options. If you have
multiple scripts awaiting a signal, you can pass an identifying argument
to await and then use pkill -f to deliver a signal to both:
# Script 1
./await database_started
# Script 2
./await database_started
# Script 3
pkill -CONT -f "await database_started"
Keep in mind that if your await is not active when the signal is
delivered, your scripts will deadlock; as such, do not attempt to use
await for complex dependency control.