Aschen / bash-promises

Bash promise is a micro bash library composed of 6 functions allowing to execute tasks in parallel in a shell script using promises.

Bash promise

Bash promise is a micro bash library composed of 6 functions allowing to execute tasks in parallel in a bash script using promise-like API.

#!/bin/bash

source promises.sh

# Init the library
init_promises

# Run a promise: promise_run <...command>
promise_run echo "start A"
  promise_then echo "Success A"
  promise_catch echo "Failure A"

See more examples

API

init_promises

Initialize the promise library.
This function should be called before using the library.

It can be called with "strict" to terminate the script and every child commands if any promise fail.
This behavior is similar to set -e.

#!/bin/sh

init_promises

# equivalent to set -e
init_promises "strict"

promise_run

Run a command in parallel and returns a promise ID.

The command is gathered with the $@ special variable.

You have to wait the promise fulfillement with either await_promise or await_promises. Otherwise the script will exit before the command execution is over.

#!/bin/sh

promise_run tar cfj /lib.tar.xz /lib

promise_then

Execute a command when the promise is resolved and returns the promise ID.
A promise is marked as resolved when the promise command returns a 0 exit code.

This method should be chain after a call to promise_run or promise_catch.

The command is gathered with the $@ special variable.

#!/bin/sh

promise_run tar cfj lib.tar.xz /lib
  promise_then scp lib.tar.xz aschen.ovh:lib.tar.xz

promise_catch

Execute a command when the promise is rejected and returns the promise ID.
A promise is marked as rejected when the promise command returns a non zero exit code.

This method should be chain after a call to promise_run or promise_then.

The command is gathered with the $@ special variable.

#!/bin/sh

promise_run tar cfj lib.tar.xz /lib
  promise_catch curl aschen.ovh/webhook?backup_fail

await_promises

Wait for every promise fulfillment.

#!/bin/sh

promise_run tar xf lib.tar.xz /lib
promise_run tar xf var.tar.xz /var
promise_run tar xf usr.tar.xz /usr

await_promises

await_promise

Wait for a promise fulfillment.
This method should be called after a call to promise_run, promise_then or promise_catch.

#!/bin/sh

promise_run tar xf lib.tar.xz /lib
await_promise