DanielSincere/Sh
`sh("echo 'Easily call shell commands with Sh'")`
Motivation
Bash scripts have gotten us pretty far, but it's difficult reasoning about control flow. And there's no type safety. Many command line tools already have decent interfaces, it's just the control flow of that could use some improvements. Sh solves this by relying on Swift control flow.
Installation
Add Sh as a dependency in your Package.swift
dependencies: [
.package(url: "https://github.com/FullQueueDeveloper/Sh.git", from: "1.0.0"),
]Writing scripts:
Fetching data from the shell
Here is a simple example, where we ask the shell for the date, formatted as seconds since 1970. We then parse a Foundation.TimeInterval, since it conforms to Codable. Last, we construct a Data, and print it.
import Sh import Foundation
let timeInterval = try sh(TimeInterval.self, "date +%s") let date = Date(timeIntervalSince1970: timeInterval) print("The date is \(date).")
Supposing this was in a script named Date, a shell session might look like this:
% spx Date [Sh] Running swift package --package-path SPX dump-package, decoding SwiftPackageDump [SPX] Running target named Date [Sh] Running swift run --package-path SPX Date Fetching https://github.com/FullQueueDeveloper/Sh.git from cache Fetched https://github.com/FullQueueDeveloper/Sh.git (0.24s) Computing version for https://github.com/FullQueueDeveloper/Sh.git Computed https://github.com/FullQueueDeveloper/Sh.git at 1.0.1 (0.37s) Fetching https://github.com/onevcat/Rainbow from cache Fetched https://github.com/onevcat/Rainbow (0.21s) Computed https://github.com/FullQueueDeveloper/Sh.git at 1.0.1 (0.00s) Computing version for https://github.com/onevcat/Rainbow Computed https://github.com/onevcat/Rainbow at 4.0.1 (0.30s) Creating working copy for https://github.com/onevcat/Rainbow Working copy of https://github.com/onevcat/Rainbow resolved at 4.0.1 Creating working copy for https://github.com/FullQueueDeveloper/Sh.git Working copy of https://github.com/FullQueueDeveloper/Sh.git resolved at 1.0.1 Building for debugging... [29/29] Linking Date Build complete! (4.96s) [Sh] Running date +%s, decoding Double The date is 2022-08-10 18:08:24 +0000.
And if all the package have resolved, a shell session might look like this:
% spx Date [Sh] Running swift package --package-path SPX dump-package, decoding SwiftPackageDump [SPX] Running target named Date [Sh] Running swift run --package-path SPX Date Building for debugging... Build complete! (0.08s) [Sh] Running date +%s, decoding Double The date is 2022-08-10 18:09:53 +0000.
A more substantial example might query op or lpass for a secret, or query terraform output for information about our infrastructure, or query Apple's agvtool for Apple version info of our Xcode project.
Long running scripts
This file might live in scripts/Sources/pre-commit/main.swift. Perhaps we want to run our tests, and confirm that the release build succeeds as well. Perhaps we want to see the output of swift test in our terminal so we can react to it, but we don't really care to immediately see any release build output, happy to send it to a log file.
import Sh import Foundation
try sh(.terminal, "swift test") try sh(.file("logs/build.log"), "swift build -c release")
Architecture
Sh adds convenience extensions to Foundation.Process.
Construction
Sh makes it easier to construct a Foundation.Process.
init(cmd: String, environment: [String: String] = [:], workingDirectory: String? = nil)
Run
Sh makes it easier to run a Process. The basic method runs the process, and returns whatever is in standard output as a Data?
func runReturningData() throws -> Data?
Sh adds some helper methods that build on this. runReturningTrimmedString parses the Data as a String and trims the whitespace.
try Process("echo hello").runReturningTrimmedString() // returns "hello"
Sh can also parse JSON output. Given a simple struct:
struct Simple: Decodable { let greeting: String }
We can parse the output like this:
let simple = try sh(Simple.self, #"echo '{"greeting": "hello"}'"#) print(simple.greeting) // prints "hello"
Async/await
Yes, Sh supports Swift's async/await. All methods have a corresponding async version.
Goals:
- Enable calling command line tools easily from Swift, since Swift offers a nicer type system than Bash or Zsh.
- Allow easy variable substitution in shell calls, and what was run in the shell can be announced to the terminal, for easy copy-paste
Package Metadata
Repository: DanielSincere/Sh
Stars: 11
Forks: 4
Open issues: 2
Default branch: trunk
Primary language: swift
License: MIT
README: README.md