Cmd

Represents a command to be executed in a child process.

Output

Represents the output of a command.

Output is a record:

{
   status : Result I32 InternalIOErr.IOErr,
   stdout : List U8,
   stderr : List U8,
}

new : Str -> Cmd

Create a new command to execute the given program in a child process.

arg : Cmd, Str -> Cmd

Add a single argument to the command. ! Shell features like variable subsitition (e.g. $FOO), glob patterns (e.g. *.txt), ... are not available.

# Represent the command "ls -l"
Cmd.new("ls")
|> Cmd.arg("-l")

args : Cmd, List Str -> Cmd

Add multiple arguments to the command. ! Shell features like variable subsitition (e.g. $FOO), glob patterns (e.g. *.txt), ... are not available.

# Represent the command "ls -l -a"
Cmd.new("ls")
|> Cmd.args(["-l", "-a"])

env : Cmd, Str, Str -> Cmd

Add a single environment variable to the command.

# Run "env" and add the environment variable "FOO" with value "BAR"
Cmd.new("env")
|> Cmd.env("FOO", "BAR")

envs : Cmd, List ( Str, Str ) -> Cmd

Add multiple environment variables to the command.

# Run "env" and add the variables "FOO" and "BAZ"
Cmd.new("env")
|> Cmd.envs([("FOO", "BAR"), ("BAZ", "DUCK")])

clear_envs : Cmd -> Cmd

Clear all environment variables, and prevent inheriting from parent, only the environment variables provided to command are available to the child.

# Represents "env" with only "FOO" environment variable set
Cmd.new("env")
|> Cmd.clear_envs
|> Cmd.env("FOO", "BAR")

output! : Cmd => Output

Execute command and capture stdout, stderr and the exit code in 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.

status! : Cmd => Result I32 [CmdStatusErr InternalIOErr.IOErr]

Execute command and inherit stdin, stdout and stderr from parent

exec! : Str, List Str => Result {} [CmdStatusErr InternalIOErr.IOErr]

Execute command and inherit stdin, stdout and stderr from parent

# Call echo to print "hello world"
Cmd.exec!("echo", ["hello world"])