rsc3/doc-schelp/HelpSource/Classes/Pipe.scrbl

88 lines
2.1 KiB
Racket

#lang scribble/manual
@(require (for-label racket))
@title{Pipe}
pipe stdin to, or stdout from, a UNIX shell command@section{related}
Classes/UnixFILE
@section{categories}
Files
@section{description}
Pipe stdin to, or stdout from, a UNIX shell command. Pipe treats the shell command as if it were a UnixFILE, and returns nil when done. See link::Classes/UnixFILE:: for details of the access methods. Pipe must be explicitly closed. Do not rely on the garbage collector to do this for you!
@section{ClassMethods}
@section{method}
new
@section{argument}
commandLine
A link::Classes/String:: representing a valid shell command.
@section{argument}
mode
A link::Classes/String:: representing the mode. Valid modes are "w" (pipe to stdin) and "r" (pipe from stdout).
@section{InstanceMethods}
@section{private}
prClose, prOpen
@section{method}
open
Open the file.
@section{argument}
commandLine
A command line link::Classes/String:: passed to popen.
@section{argument}
mode
A link::Classes/String:: passed to popen, so should be one of: "r","w"
@section{method}
close
Closes the pipe, waiting for the command to finish. You must do this explicitly before the Pipe object is garbage collected.
@section{returns}
The exit status of the command (an Integer).
@section{Examples}
@section{note}
For anyone still using macOS 10.3, UNIX commands like pipe do not work when the server is booted; quit the server, otherwise SuperCollider crashes. More recent macOS is not affected.
::
@racketblock[
// this pipes in stdout from ls
(
var p, l;
p = Pipe.new("ls -l", "r"); // list directory contents in long format
l = p.getLine; // get the first line
while({l.notNil}, {l.postln; l = p.getLine; }); // post until l = nil
p.close; // close the pipe to avoid that nasty buildup
)
::
A more time-intensive request:
]
@racketblock[
(
var p, l;
p = Pipe.new("ping -c10 sourceforge.net", "r"); // list directory contents in long format
l = p.getLine; // get the first line
while({l.notNil}, {l.postln; l = p.getLine; }); // post until l = nil
p.close; // close the pipe to avoid that nasty buildup
)
::
]