await

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.

See Also

• kill(1)
• signal(3)