Shell scripting in Swift

George Lyon

Last update: Sep 15, 2022

Related tags

Command Line Shwift

Overview

Shwift

Shell-scripting in Swift

DISCLAIMER: Shwift depends on Swift's incoming concurrency features. As such, it requires a recent Swift toolchain, and changes in the toolchain may break provided functionality without notice. This project was last seen working with the 2021-05-04 toolchain in Xcode.

Overview

Shwift aims to provide a full-featured framework for creating shell-script-like tools using Swift. We are particularly excited about the prospect of building scripts using swift-argument-parser.

Shwift is built around two salient design points. Firstly, we want running a shell command to behave as similarly as possible to invoking a regular Swift function. For instance, we should be able to set a breakpoint on a line containing try await echo("Foo") | sed("s/Foo/Bar/"), and stepping over this line should log Bar to the standard out. Second we want piping between executables and native Swift code to be as low-friction as possible . Indeed, in the earlier example echo is a builtin implemented in Swift. We also aim to offer more sophisticated builtins for interfacing with shell scripts. The first of these is process which allows the user to process as much input as they need and return a Swift value.

We recommend looking at Sample.swift for a few examples of how this can be used.

Comments

NIO provides basic async/await API already

https://github.com/GeorgeLyon/Shwift/blob/8fb57012a1555cdd62243ac6504018f9b6fcddd5/Sources/Shwift/NIO.swift#L5

They are :). If you import _NIOConcurrency, then you should be able to just use try await channel.close(). EventLoopFuture also has func get() async throws, and EventLoopPromise can be fulfilled with an async computation.

--> https://github.com/apple/swift-nio/blob/main/Sources/_NIOConcurrency/AsyncAwaitSupport.swift

opened by weissi 1
Dust off documentation and clean up some API

This commit adds a bunch of documentation to various parts of Shwift.

It also tweaks a few APIs, most notably removing the API for reading values from Environment. This is because Environment is only designed to pass an environment to a command-line tool, and not as a dictionary of environment variables (for instance, it uses a linear scan to get values from the environment when it needs to).

opened by GeorgeLyon 0
Add `Process.launch` which returns after exec

Process.launch returns a Task which represents the running executable. This task can be cancelled and awaited like any other Swift Task. Cancellation sends SIGTERM to the child.

opened by GeorgeLyon 0
Come up with better API for abstracting file descriptors

Currently, projects which use Shwift end up with some awkwardly nested structures when using Output and Input as file descriptors. This feels especially bloated when dealing with "null" inputs like nullDevice. We can probably do better.

opened by GeorgeLyon 0
Command hangs when piped to a builtin which does not read from the input

Uncommenting the following test demonstrates the issue: https://github.com/GeorgeLyon/Shwift/blob/8c9e74c1b091e019b85805fc84706760fce54fcc/Tests/ShellTests/Shell%20Tests.swift#L108-L114

opened by GeorgeLyon 0

Releases(2.0.0)

2.0.0(Oct 3, 2022)

This 2.0 release does not profoundly change the API of Shwift or Script. It does remove a (likely unused) public API to read a value from an Environment.

As an added bonus, Shwift is cleaned up for Swift 5.7 and much of the documentation has been improved.
Source code(tar.gz)
Source code(zip)
1.2.1(Jan 11, 2022)
What's Changed

Add public init for Recorder by @GeorgeLyon in https://github.com/GeorgeLyon/Shwift/pull/12

Full Changelog: https://github.com/GeorgeLyon/Shwift/compare/1.2.0...1.2.1
Source code(tar.gz)
Source code(zip)
1.2.0(Jan 11, 2022)
What's Changed

Add Recorable Output by @GeorgeLyon in https://github.com/GeorgeLyon/Shwift/pull/11

Full Changelog: https://github.com/GeorgeLyon/Shwift/compare/1.1.0...1.2.0
Source code(tar.gz)
Source code(zip)
1.1.0(Dec 29, 2021)
What's Changed

Prefer CancellationError to uncaught SIGTERM by @GeorgeLyon in https://github.com/GeorgeLyon/Shwift/pull/8

Add Process.launch which returns after exec by @GeorgeLyon in https://github.com/GeorgeLyon/Shwift/pull/9

Full Changelog: https://github.com/GeorgeLyon/Shwift/compare/1.0.2...1.0.3
Source code(tar.gz)
Source code(zip)
1.0.2(Dec 10, 2021)
What's Changed

Add pipe variant where destination is PipableCommand by @GeorgeLyon in https://github.com/GeorgeLyon/Shwift/pull/7

Also format tests by @GeorgeLyon in https://github.com/GeorgeLyon/Shwift/pull/6

Full Changelog: https://github.com/GeorgeLyon/Shwift/compare/1.0.1...1.0.2
Source code(tar.gz)
Source code(zip)
1.0.1(Dec 10, 2021)
What's Changed

Fix throwing on nonzero exit status by @GeorgeLyon in https://github.com/GeorgeLyon/Shwift/pull/5

Full Changelog: https://github.com/GeorgeLyon/Shwift/compare/1.0.0...1.0.1
Source code(tar.gz)
Source code(zip)