Rust shell - shell script written in rust.

This is not an officially supported Google product

Rust shell is a helper library for std::process::Command to write shell script like tasks in rust. The library only works with unix-like operation systems.

Run command

run! macro creates a ShellCommand instance which you can run by run() method.

#[macro_use] extern crate shell;

// Run command by cmd! macro
cmd!("echo Hello rust shell!").run().unwrap();

// Contain white space or non-alphabetical characters
cmd!("echo \"%$#\"").run().unwrap();

// Pass an argument
let name = "shell";
cmd!("echo Hello rust {}!", name).run().unwrap();

// Extract environment variable
cmd!("echo HOME is $HOME").run().unwrap();

ShellResult

The return value of ShellCommand#run() is ShellResult which is Ok(_) only when the command successfully runs and its execution code is 0, so you can use ? operator to check if the command successfully exits or not.

#[macro_use] extern crate shell;
use shell::ShellResult;

fn shell_function() -> ShellResult {
  cmd!("echo Command A").run()?;
  cmd!("echo Command B").run()?;
  shell::ok()
}

Output string

ShellCommand has a shorthand to obtain stdout as UTF8 string.

#[macro_use] extern crate shell;

assert_eq!(cmd!("echo OK").stdout_utf8().unwrap(), "OK\n");

Spawn

ShellCommand has spawn() method which runs the command asynchronously and returns ShellChild.

#[macro_use] extern crate shell;
extern crate libc;
use shell::ShellResultExt;

// Wait
let child = cmd!("sleep 2").spawn().unwrap();
child.wait().unwrap();

// Signal
let child = cmd!("sleep 2").spawn().unwrap();
child.signal(libc::SIGINT);
let result = child.wait();
assert!(result.is_err(), "Should be error as it exits with a signal");
assert!(result.status().is_ok(), "Still able to obtain status");

Thread

If you would like to run a sequence of commands asynchronously, shell::spawn creates a thread as well as std::thread::spawn but it returns ShellHandle wrapping std::thread::JoinHandle.

ShellHandle#signal() is used to send a signal to processes running on the thread. It also stops launching a new process by ShellComamnd::run() on that thread.

#[macro_use] extern crate shell;
extern crate libc;
use shell::ShellResult;
use shell::ShellResultExt;

let handle = shell::spawn(|| -> ShellResult {
  cmd!("sleep 3").run()
});
handle.signal(libc::SIGINT);
let result = handle.join().unwrap();
assert!(result.is_err(), "Should be error as it exits with a signal");
assert!(result.status().is_ok(), "Still able to obtain status");

Signal handling

trap_signal_and_wait_children() starts watching SIGINT and SIGTERM, and waits all child processes before exiting the process when receiving these signals. The function needs to be called before launching any new thread.

extern crate shell;
shell::trap_signal_and_wait_children().unwrap();

Access underlaying objects

ShellComamnd wraps std::process::Command and ShellChild wraps std::process::Child. Both underlaying objects are accessible via public fields.

#[macro_use] extern crate shell;
use std::process::Stdio;
use std::io::Read;

// Access std::process::Command.
let mut shell_command = cmd!("echo OK");
{
  let mut command = &mut shell_command.command;
  command.stdout(Stdio::piped());
}

// Access std::process::Child.
let shell_child = shell_command.spawn().unwrap();
{
  let mut lock = shell_child.0.write().unwrap();
  let mut child = &mut lock.as_mut().unwrap().child;
  let mut str = String::new();
  child.stdout.as_mut().unwrap().read_to_string(&mut str);
}
shell_child.wait().unwrap();

License

Apatch 2 License

google/rust-shell