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Description:

process runner

Process #
The process_runner package for Dart uses the ProcessManager class from
process package to allow invocation of external OS processes, and manages
the stderr and stdout properly so that you don't lose any output, and can easily
access it without needing to wait on streams.
Like dart:io and process, it supplies a rich, Dart-idiomatic API for
spawning OS processes, with the added benefit of easy retrieval of stdout and
stderr from the result of running the process, with proper waiting for the
process and stderr/stdout streams to be closed. Because it uses process, you
can supply a mocked ProcessManager to allow testing of code that uses
process_runner.
In addition to being able to launch processes separately with ProcessRunner,
it allows creation of a pool of worker processes with ProcessPool, and
manages running them with a set number of active WorkerJobs, and manages the
collection of their stdout, stderr, and interleaved stdout and stderr output.
See the example and process_runner library docs for
more information on how to use it, but the basic usage for is:
import 'package:process_runner/process_runner.dart';

Future<void> main() async {
ProcessRunner processRunner = ProcessRunner();
ProcessRunnerResult result = await processRunner.runProcess(['ls']);

print('stdout: ${result.stdout}');
print('stderr: ${result.stderr}');

// Print interleaved stdout/stderr:
print('combined: ${result.output}');
}
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For the ProcessPool, also see the example,
but it basically looks like this:
import 'package:process_runner/process_runner.dart';

Future<void> main() async {
ProcessPool pool = ProcessPool(numWorkers: 2);
final List<WorkerJob> jobs = <WorkerJob>[
WorkerJob(['ls'], name: 'Job 1'),
WorkerJob(['df'], name: 'Job 2'),
];
await for (final WorkerJob job in pool.startWorkers(jobs)) {
print('\nFinished job ${job.name}');
}
}
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Or, if you just want the answer when it's done:
import 'package:process_runner/process_runner.dart';

Future<void> main() async {
ProcessPool pool = ProcessPool(numWorkers: 2);
final List<WorkerJob> jobs = <WorkerJob>[
WorkerJob(['ls'], name: 'Job 1'),
WorkerJob(['df'], name: 'Job 2'),
];
List<WorkerJob> finishedJobs = await pool.runToCompletion(jobs);
for (final WorkerJob job in finishedJobs) {
print("${job.name}: ${job.result.stdout}");
}
}
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process_runner utility #
The example can also be installed and run as a useful command-line utility. You can install it using:
dart pub global activate process_runner
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And you can run it with:
dart pub global run process_runner
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The above steps will work on any Dart-supported platform.
Of course, you can also just compile the example into a native executable and move it to a directory in your PATH:
dart compile exe bin/process_runner.dart -o process_runner
mv process_runner /some/bin/dir/in/your/path
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The usage for the utility is as follows:
process_runner [--help] [--quiet] [--report] [--stdout] [--stderr]
[--run-in-shell] [--working-directory=<working directory>]
[--jobs=<num_worker_jobs>] [--command="command" ...]
[--source=<file|"-"> ...]:
-h, --help Print help for process_runner.
-q, --quiet Silences the stderr and stdout output of the
commands. This is a shorthand for "--no-stdout
--no-stderr".
-r, --report Print progress on the jobs to stderr while running.
--[no-]stdout Prints the stdout output of the commands to stdout in
the order they complete. Will not interleave lines
from separate processes. Has no effect if --quiet is
specified.
(defaults to on)
--[no-]stderr Prints the stderr output of the commands to stderr in
the order they complete. Will not interleave lines
from separate processes. Has no effect if --quiet is
specified
(defaults to on)
--run-in-shell Run the commands in a subshell.
--[no-]fail-ok If set, allows continuing execution of the remaining
commands even if one fails to execute. If not set,
("--no-fail-ok") then process will just exit with a
non-zero code at completion if there were any jobs
that failed.
-j, --jobs Specify the number of worker jobs to run
simultaneously. Defaults to the number of processor
cores on the machine.
--working-directory Specify the working directory to run in.
(defaults to ".")
-c, --command Specify a command to add to the commands to be run.
Commands specified with this option run before those
specified with --source. Be sure to quote arguments
to --command properly on the command line.
-s, --source Specify the name of a file to read commands from, one
per line, as they would appear on the command line,
with spaces escaped or quoted. Specify "--source -"
to read from stdin. More than one --source argument
may be specified, and they will be concatenated in
the order specified. The stdin ("--source -")
argument may only be specified once.
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