CODEWITHSUNDEEP
rust
Daniel YC Lin
Daniel YC Lin

Reputation: 15992

call shell run pipeline failed in rust's Command.output

I'm trying to get result from call shell and grep the result. But it failed, in shell, it works.

use std::process::Command;

fn main() {
    let result = Command::new("sh")
        .arg("-c")
        .arg("last")                // by this line it works
        // .arg("last | grep 'still logged in'")  // by this line, it will return 256 code
        .output()
        .expect("'last' command failed to start");
    println!("{:?}", result);
}

Upvotes: 2

Views: 138

Answers (1)

Chayim Friedman
Chayim Friedman

Reputation: 70840

https://doc.rust-lang.org/stable/std/process/struct.ExitStatus.html

An ExitStatus represents every possible disposition of a process. On Unix this is the wait status. It is not simply an exit status (a value passed to exit).

See I used wait(&status) and the value of status is 256, why?. grep returns 1 as no match was found, and this becomes an exist status of 256.

If you want the exit code, call output.status.code(). This correctly returns Some(1).

Upvotes: 2

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