Function std.process.pipeProcess

pipeProcess and pipeShell are convenient wrappers around spawnProcess and spawnShell, respectively, and automate the task of redirecting one or more of the child process' standard streams through pipes. Like the functions they wrap, these functions return immediately, leaving the child process to execute in parallel with the invoking process. It is recommended to always call wait on the returned ProcessPipes.pid, as detailed in the documentation for wait.

The args/program/command, env and config parameters are forwarded straight to the underlying spawn functions, and we refer to their documentation for details.

Prototypes

ProcessPipes pipeProcess(
  const(char[][]) args,
  Redirect redirect = cast(Redirect)7,
  const(string[string]) env = cast(const(string[string]))null,
  Config config = cast(Config)0,
  const(char[]) workDir = null
) @safe;

ProcessPipes pipeProcess(
  const(char[]) program,
  Redirect redirect = cast(Redirect)7,
  const(string[string]) env = cast(const(string[string]))null,
  Config config = cast(Config)0,
  const(char[]) workDir = null
) @safe;

Parameters

Returns

A ProcessPipes object which contains std.stdio.File handles that communicate with the redirected streams of the child process, along with a Pid object that corresponds to the spawned process.

Throws

ProcessException on failure to start the process.
std.stdio.StdioException on failure to redirect any of the streams.

Example

// my_application writes to stdout and might write to stderr
auto pipes = pipeProcess("my_application", Redirect.stdout | Redirect.stderr);
scope(exit) wait(pipes.pid);

// Store lines of output.
string[] output;
foreach (line; pipes.stdout.byLine) output ~= line.idup;

// Store lines of errors.
string[] errors;
foreach (line; pipes.stderr.byLine) errors ~= line.idup;


// sendmail expects to read from stdin
pipes = pipeProcess(["/usr/bin/sendmail", "-t"], Redirect.stdin);
pipes.stdin.writeln("To: you");
pipes.stdin.writeln("From: me");
pipes.stdin.writeln("Subject: dlang");
pipes.stdin.writeln("");
pipes.stdin.writeln(message);

// a single period tells sendmail we are finished
pipes.stdin.writeln(".");

// but at this point sendmail might not see it, we need to flush
pipes.stdin.flush();

// sendmail happens to exit on ".", but some you have to close the file:
pipes.stdin.close();

// otherwise this wait will wait forever
wait(pipes.pid);