Rust by Example

43 Child processes

The ProcessOutput struct represents the output of a finished child process. And the Command struct is a process builder.

#![feature(io)] use std::old_io::process::{Command,ProcessOutput}; fn main() { // Initial command `rustc` let mut cmd = Command::new("rustc"); // append the "--version" flag to the command cmd.arg("--version"); // The `output` method will spawn `rustc --version`, wait until the process // finishes and return the output of the process match cmd.output() { Err(why) => panic!("couldn't spawn rustc: {}", why.desc), // Destructure `ProcessOutput` Ok(ProcessOutput { error: err, output: out, status: exit }) => { // Check if the process succeeded, i.e. the exit code was 0 if exit.success() { // `out` has type `Vec<u8>`, convert it to a UTF-8 `$str` let s = String::from_utf8_lossy(&out); print!("rustc succeeded and stdout was:\n{}", s); } else { // `err` also has type `Vec<u8>` let s = String::from_utf8_lossy(&err); print!("rustc failed and stderr was:\n{}", s); } }, } }

(You are encouraged to try the previous example with an incorrect flag passed to rustc)