Struct std::process::Command

Constructs a new Command for launching the program at path program, with the following default configuration:

• No arguments to the program
• Inherit the current process’s environment
• Inherit the current process’s working directory
• Inherit stdin/stdout/stderr for spawn or status, but create pipes for output

Builder methods are provided to change these defaults and otherwise configure the process.

If program is not an absolute path, the PATH will be searched in an OS-defined way.

The search path to be used may be controlled by setting the PATH environment variable on the Command, but this has some implementation limitations on Windows (see issue #37519).

Examples

Basic usage:

use std::process::Command;

Command::new("sh")
        .spawn()
        .expect("sh command failed to start");

Adds an argument to pass to the program.

Only one argument can be passed per use. So instead of:

.arg("-C /path/to/repo")

usage would be:

.arg("-C")
.arg("/path/to/repo")

To pass multiple arguments see args.

Note that the argument is not passed through a shell, but given literally to the program. This means that shell syntax like quotes, escaped characters, word splitting, glob patterns, substitution, etc. have no effect.

Examples

Basic usage:

use std::process::Command;

Command::new("ls")
        .arg("-l")
        .arg("-a")
        .spawn()
        .expect("ls command failed to start");

Adds multiple arguments to pass to the program.

To pass a single argument see arg.

Note that the arguments are not passed through a shell, but given literally to the program. This means that shell syntax like quotes, escaped characters, word splitting, glob patterns, substitution, etc. have no effect.

Examples

Basic usage:

use std::process::Command;

Command::new("ls")
        .args(["-l", "-a"])
        .spawn()
        .expect("ls command failed to start");

Inserts or updates an environment variable mapping.

Note that environment variable names are case-insensitive (but case-preserving) on Windows, and case-sensitive on all other platforms.

Examples

Basic usage:

use std::process::Command;

Command::new("ls")
        .env("PATH", "/bin")
        .spawn()
        .expect("ls command failed to start");

Adds or updates multiple environment variable mappings.

Examples

Basic usage:

use std::process::{Command, Stdio};
use std::env;
use std::collections::HashMap;

let filtered_env : HashMap<String, String> =
    env::vars().filter(|&(ref k, _)|
        k == "TERM" || k == "TZ" || k == "LANG" || k == "PATH"
    ).collect();

Command::new("printenv")
        .stdin(Stdio::null())
        .stdout(Stdio::inherit())
        .env_clear()
        .envs(&filtered_env)
        .spawn()
        .expect("printenv failed to start");

Removes an environment variable mapping.

Examples

Basic usage:

use std::process::Command;

Command::new("ls")
        .env_remove("PATH")
        .spawn()
        .expect("ls command failed to start");

Clears the entire environment map for the child process.

Examples

Basic usage:

use std::process::Command;

Command::new("ls")
        .env_clear()
        .spawn()
        .expect("ls command failed to start");

Sets the working directory for the child process.

Platform-specific behavior

If the program path is relative (e.g., "./script.sh"), it’s ambiguous whether it should be interpreted relative to the parent’s working directory or relative to current_dir. The behavior in this case is platform specific and unstable, and it’s recommended to use canonicalize to get an absolute program path instead.

Examples

Basic usage:

use std::process::Command;

Command::new("ls")
        .current_dir("/bin")
        .spawn()
        .expect("ls command failed to start");

Configuration for the child process’s standard input (stdin) handle.

Defaults to inherit when used with spawn or status, and defaults to piped when used with output.

Examples

Basic usage:

use std::process::{Command, Stdio};

Command::new("ls")
        .stdin(Stdio::null())
        .spawn()
        .expect("ls command failed to start");

Configuration for the child process’s standard output (stdout) handle.

Defaults to inherit when used with spawn or status, and defaults to piped when used with output.

Examples

Basic usage:

use std::process::{Command, Stdio};

Command::new("ls")
        .stdout(Stdio::null())
        .spawn()
        .expect("ls command failed to start");

Configuration for the child process’s standard error (stderr) handle.

Defaults to inherit when used with spawn or status, and defaults to piped when used with output.

Examples

Basic usage:

use std::process::{Command, Stdio};

Command::new("ls")
        .stderr(Stdio::null())
        .spawn()
        .expect("ls command failed to start");

Executes the command as a child process, returning a handle to it.

By default, stdin, stdout and stderr are inherited from the parent.

Examples

Basic usage:

use std::process::Command;

Command::new("ls")
        .spawn()
        .expect("ls command failed to start");

Executes the command as a child process, waiting for it to finish and collecting all of its output.

By default, stdout and stderr are captured (and used to provide the resulting output). Stdin is not inherited from the parent and any attempt by the child process to read from the stdin stream will result in the stream immediately closing.

Examples

use std::process::Command;
use std::io::{self, Write};
let output = Command::new("/bin/cat")
                     .arg("file.txt")
                     .output()
                     .expect("failed to execute process");

println!("status: {}", output.status);
io::stdout().write_all(&output.stdout).unwrap();
io::stderr().write_all(&output.stderr).unwrap();

assert!(output.status.success());

Executes a command as a child process, waiting for it to finish and collecting its status.

By default, stdin, stdout and stderr are inherited from the parent.

Examples

use std::process::Command;

let status = Command::new("/bin/cat")
                     .arg("file.txt")
                     .status()
                     .expect("failed to execute process");

println!("process finished with: {}", status);

assert!(status.success());

Returns the path to the program that was given to Command::new.

Examples

use std::process::Command;

let cmd = Command::new("echo");
assert_eq!(cmd.get_program(), "echo");

Returns an iterator of the arguments that will be passed to the program.

This does not include the path to the program as the first argument; it only includes the arguments specified with Command::arg and Command::args.

Examples

use std::ffi::OsStr;
use std::process::Command;

let mut cmd = Command::new("echo");
cmd.arg("first").arg("second");
let args: Vec<&OsStr> = cmd.get_args().collect();
assert_eq!(args, &["first", "second"]);

Returns an iterator of the environment variables that will be set when the process is spawned.

Each element is a tuple (&OsStr, Option<&OsStr>), where the first value is the key, and the second is the value, which is None if the environment variable is to be explicitly removed.

This only includes environment variables explicitly set with Command::env, Command::envs, and Command::env_remove. It does not include environment variables that will be inherited by the child process.

Examples

use std::ffi::OsStr;
use std::process::Command;

let mut cmd = Command::new("ls");
cmd.env("TERM", "dumb").env_remove("TZ");
let envs: Vec<(&OsStr, Option<&OsStr>)> = cmd.get_envs().collect();
assert_eq!(envs, &[
    (OsStr::new("TERM"), Some(OsStr::new("dumb"))),
    (OsStr::new("TZ"), None)
]);

Returns the working directory for the child process.

This returns None if the working directory will not be changed.

Examples

use std::path::Path;
use std::process::Command;

let mut cmd = Command::new("ls");
assert_eq!(cmd.get_current_dir(), None);
cmd.current_dir("/bin");
assert_eq!(cmd.get_current_dir(), Some(Path::new("/bin")));