on-broken-pipe

The tracking issue for this feature is: #97889

Note: The ui for this feature was previously an attribute named #[unix_sigpipe = "..."].

Overview

The -Zon-broken-pipe=... compiler flag can be used to specify how libstd shall setup SIGPIPE on Unix platforms before invoking fn main(). This flag is ignored on non-Unix targets. The flag can be used with three different values or be omitted entirely. It affects SIGPIPE before fn main() and before children get exec()'ed:

-Zon-broken-pipe not used

If -Zon-broken-pipe is not used, libstd will behave in the manner it has since 2014, before Rust 1.0. SIGPIPE will be set to SIG_IGN before fn main() and result in EPIPE errors which are converted to std::io::ErrorKind::BrokenPipe.

When spawning child processes, SIGPIPE will be set to SIG_DFL before doing the underlying exec() syscall.

-Zon-broken-pipe=kill

Set the SIGPIPE handler to SIG_DFL before invoking fn main(). This will result in your program getting killed if it tries to write to a closed pipe. This is normally what you want if your program produces textual output.

When spawning child processes, SIGPIPE will not be touched. This normally means child processes inherit SIG_DFL for SIGPIPE.

Example

fn main() {
    loop {
        println!("hello world");
    }
}

$ rustc -Zon-broken-pipe=kill main.rs
$ ./main | head -n1
hello world

-Zon-broken-pipe=error

Set the SIGPIPE handler to SIG_IGN before invoking fn main(). This will result in ErrorKind::BrokenPipe errors if you program tries to write to a closed pipe. This is normally what you want if you for example write socket servers, socket clients, or pipe peers.

When spawning child processes, SIGPIPE will not be touched. This normally means child processes inherit SIG_IGN for SIGPIPE.

Example

fn main() {
    loop {
        println!("hello world");
    }
}

$ rustc -Zon-broken-pipe=error main.rs
$ ./main | head -n1
hello world
thread 'main' panicked at library/std/src/io/stdio.rs:1118:9:
failed printing to stdout: Broken pipe (os error 32)
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

-Zon-broken-pipe=inherit

Leave SIGPIPE untouched before entering fn main(). Unless the parent process has changed the default SIGPIPE handler from SIG_DFL to something else, this will behave the same as -Zon-broken-pipe=kill.

When spawning child processes, SIGPIPE will not be touched. This normally means child processes inherit SIG_DFL for SIGPIPE.