#shell #command #process #env #set #string #variables

command-builder

A wrapper around std::process::Command that allows combining/chaining diffrent commands

2 unstable releases

0.2.0 Aug 4, 2020
0.1.0 Jul 15, 2020

#263 in #env


Used in brew

MIT/Apache

19KB
490 lines

Command-Builder

I thought that the std::process::Command was not ergonomic to use, mostly due to it's transient nature. This crate facilitates an ergonomic and reusable/printable wrapper around the Command process. I implement Debug (which displays like a sh script) as well as the set of common logical operators (&&, ||, |, ;) to use shell commands.

Motivating Example

// I was interested in bundling a set of commands, then exporting them with certain environmental variables set. 
// For debugging purposes, I wanted to see what commands had been run . I ended up with functions like this:
fn call_brew(primary_arg: String, opts: &[String], env: &HashMap);
// This would call a command like so:
// brew install (opts)* primary_arg 
// plus the env configuration. I was also handling logic like 
if test_for_brew()? {
    call_brew()
} else {
    Err(BrewNotFound)
}
// when my mental model was 
brew 2&> /null && brew command

// The last pain point was debug. I wanted non-transient commands to exist. This would allow me to collect 
// and search previous commands. 

This library wrappes the std::process::Command with a struct that holds the information necessary to compute the command. This struct is then clonable, printable (with debug)

Using command-builder

use command_builder::{Command, Single};
let grep_for = Single::new("grep").a("ip").a("-c");
let direct_input = "lorim ipsum, spelling in latin is hard.";
let latin_file = Single::new("cat").a("file_name");
let searched_file = latin_file.pipe(grep_for);
let direct_search = grep_for.input(direct_input);
// Is the file what we expect?
searched_file.run()?.stdout() == direct_seach.run()?.stdout()
// confirm the commands were right
println!("searched_file: {:?}", searched_file);
// cat file_name | grep ip -c
println!("direct_search: {:?}", direct_search);
// grep ip -c < "lorim ipsum, spelling in latin is hard."

No runtime deps