Systems Programming: Shells and Processes | Schema Programming Part 28

Code on GitHub: All examples from this tutorial are available at racket-programming-series/28-systems-programming — clone the repo and follow along!

Racket is an excellent alternative to Bash or Python for gling system tasks together.

Running Commands (system)

The simplest way to run a command:

(system "ls -F") ; Returns #t if successful

Capturing Output (process)

To get the output of a command into Racket:

(match-define (list stdout stdin pid stderr control) 
              (process "ls"))

(display (port->string stdout))
(close-input-port stdout)
(close-output-port stdin)
(close-input-port stderr)

Paths and Filesystem

Racket handles cross-platform paths gracefully.

(build-path "usr" "local" "bin") 
; On Windows: "usr\local\bin"
; On Unix: "usr/local/bin"

(file-exists? "config.json")
(directory-list)

Rash: Racket as a Shell

There is even a language #lang rash that mixes Racket and Bash syntax!

#lang rash
ls -a | grep ".rkt"

Summary

Racket scripts are robust, fast, and cross-platform. You can use Racket to automate builds, manage files, or orchestration tools.