Trait std::os::unix::process::CommandExt [−] [src]

pub trait CommandExt {
    fn uid(&mut self, id: u32) -> &mut Command;
    fn gid(&mut self, id: u32) -> &mut Command;
    fn session_leader(&mut self, on: bool) -> &mut Command;
    fn before_exec<F>(&mut self, f: F) -> &mut Command where F: FnMut() -> Result<()> + Send + Sync + 'static;
    fn exec(&mut self) -> Error;
}

Unix-specific extensions to the std::process::Command builder

Required Methods

fn uid(&mut self, id: u32) -> &mut Command

Sets the child process's user id. This translates to a setuid call in the child process. Failure in the setuid call will cause the spawn to fail.

fn gid(&mut self, id: u32) -> &mut Command

Similar to uid, but sets the group id of the child process. This has the same semantics as the uid field.

fn session_leader(&mut self, on: bool) -> &mut Command

Deprecated since 1.9.0

: use before_exec instead

Create a new session (cf. setsid(2)) for the child process. This means that the child is the leader of a new process group. The parent process remains the child reaper of the new process.

This is not enough to create a daemon process. The init process should be the child reaper of a daemon. This can be achieved if the parent process exit. Moreover, a daemon should not have a controlling terminal. To achieve this, a session leader (the child) must spawn another process (the daemon) in the same session.

fn before_exec<F>(&mut self, f: F) -> &mut Command where F: FnMut() -> Result<()> + Send + Sync + 'static

Unstable (process_exec #31398)

Schedules a closure to be run just before the exec function is invoked.

The closure is allowed to return an I/O error whose OS error code will be communicated back to the parent and returned as an error from when the spawn was requested.

Multiple closures can be registered and they will be called in order of their registration. If a closure returns Err then no further closures will be called and the spawn operation will immediately return with a failure.

Notes

This closure will be run in the context of the child process after a fork. This primarily means that any modificatons made to memory on behalf of this closure will not be visible to the parent process. This is often a very constrained environment where normal operations like malloc or acquiring a mutex are not guaranteed to work (due to other threads perhaps still running when the fork was run).

When this closure is run, aspects such as the stdio file descriptors and working directory have successfully been changed, so output to these locations may not appear where intended.

fn exec(&mut self) -> Error1.9.0

Performs all the required setup by this Command, followed by calling the execvp syscall.

On success this function will not return, and otherwise it will return an error indicating why the exec (or another part of the setup of the Command) failed.

This function, unlike spawn, will not fork the process to create a new child. Like spawn, however, the default behavior for the stdio descriptors will be to inherited from the current process.

Notes

The process may be in a "broken state" if this function returns in error. For example the working directory, environment variables, signal handling settings, various user/group information, or aspects of stdio file descriptors may have changed. If a "transactional spawn" is required to gracefully handle errors it is recommended to use the cross-platform spawn instead.

Implementors