merklebros/debounce.sh

A generic debounce for Bash

🎱 debounce.sh

A generic debounce for Bash.

Debouncing is the process of taking multiple sequential events of the same type and grouping them together as one. By treating a group of events as one event, you can handle them all at once instead of handling each event individually.

Debounce is often used in front-end design for things like autosaving a form that a user is typing in - but only after they have finished typing for some time (all keypress events are grouped together and treated as one).

Debouncing requires an event generating program and an action to run when the event generating program has not generated an event for a certain time interval.

Usage

Pass three parameters to debounce.sh:

1. DEBOUNCE_PROGRAM: a program that you want to run continuously but that periodically returns successfully when an event occurs (ex a file watcher like inotifywait that returns successfully when a file is changed).
2. DEBOUNCE_INTERVAL_SECONDS: a time interval in seconds to wait when the debounce program returns successfully
3. DEBOUNCE_ACTION: a program that runs when the DEBOUNCE_PROGRAM has not generated new events for DEBOUNCE_INTERVAL_SECONDS seconds.

Generic usage:

./debounce.sh ./debounce_program.sh debounce_interval_seconds ./debounce_action.sh

Watch standard input and print "Ran action" whenever text has been submitted to standard input but not submitted again for 5 seconds

./debounce.sh "read" 5 "echo 'Ran action'"

Watch my technical journal file and run an action whenever it has been saved but not saved again for 10 seconds

./debounce.sh ./inotifywait-debounce.sh 10 ./action.sh

Tests

Tests are written with Bash Automated Testing Systems 2018 (bats-core).

Run tests in test/:

bats test.bats