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{{task|Programming environment operations}}
;Task:
Spawn a new [[process]] which can run simultaneously with, and independently of, the original parent process.
<br><br>
=={{header|Ada}}==
{{libheader|POSIX}}
<syntaxhighlight lang="ada">with Ada.Text_IO,
POSIX.Process_Identification,
POSIX.Unsafe_Process_Primitives;
procedure Fork is
use Ada.Text_IO,
POSIX.Process_Identification,
POSIX.Unsafe_Process_Primitives;
begin
if Fork = Null_Process_ID then
Put_Line ("This is the new process.");
else
Put_Line ("This is the original process.");
end if;
exception
when others =>
Put_Line ("Something went wrong.");
end Fork;</syntaxhighlight>
=={{header|Aikido}}==
<syntaxhighlight lang="aikido">
var pid = fork()
switch (pid) {
case <0:
println ("fork error")
break
case 0:
println ("child")
break
default:
println ("parent")
break
}
</syntaxhighlight>
=={{header|ALGOL 68}}==
Line 5 ⟶ 47:
{{works with|ALGOL 68G|Any - tested with release mk15-0.8b.fc9 - "fork" is not part of the standard's prelude.}}
<syntaxhighlight lang="algol68">main:
(
INT pid;
Line 16 ⟶ 57:
print("ERROR: Something went wrong")
FI
)</syntaxhighlight>
Output:
<pre>
Line 23 ⟶ 63:
This is the original process
</pre>
=={{header|AutoHotkey}}==
<syntaxhighlight lang="autohotkey">MsgBox, 4, Fork, Start another process?
IfMsgBox, Yes
Run, %
MsgBox, 0, Fork, Stop this process.</syntaxhighlight>
=={{header|BASIC}}==
==={{header|BaCon}}===
<syntaxhighlight lang="freebasic">' Fork
pid = FORK
IF pid = 0 THEN
PRINT "I am the child, my PID is:", MYPID
ENDFORK
ELIF pid > 0 THEN
PRINT "I am the parent, pid of child:", pid
REPEAT
PRINT "Waiting for child to exit"
SLEEP 50
UNTIL REAP(pid)
ELSE
PRINT "Error in fork"
ENDIF</syntaxhighlight>
{{out}}
<pre>prompt$ bacon fork.bac
Converting 'fork.bac'... done, 14 lines were processed in 0.004 seconds.
Compiling 'fork.bac'... cc -c fork.bac.c
cc -o fork fork.bac.o -lbacon -lm
Done, program 'fork' ready.
prompt$ ./fork
I am the parent, pid of child:12733
Waiting for child to exit
I am the child, my PID is:12733</pre>
==={{header|FreeBASIC}}===
In Windows without using windows.bi, we can use a vbscript command.
<syntaxhighlight lang="freebasic">
Function script(s As String) As String
Dim As String g = _
"Set WshShell = WScript.CreateObject(""WScript.Shell"")" + _
Chr(13,10) + "Return = WshShell.Run("""+s+" "",1,0)"
Return g
End Function
Function guardaArchivo(nombreArchivo As String, p As String) As String
Dim As Long n = Freefile
If Open (nombreArchivo For Binary Access Write As #n) = 0 Then
Put #n,,p
Close
Else
Print "No se puede guardar " + nombreArchivo : Sleep : End
End If
Return nombreArchivo
End Function
Sub ejecutaScript(nombreArchivo As String)
Shell "cscript.exe /Nologo " + nombreArchivo
End Sub
Var g = script("notepad.exe") '<< ejecuta este .exe (notepad como demo)
guardaArchivo("script.vbs",g)
ejecutaScript("script.vbs")
Dim As String s
Print "Hola"
Input "Teclee algo: ", s
Print s
Kill "script.vbs"
Sleep
</syntaxhighlight>
==={{header|Run BASIC}}===
You can run a program until that program executes a wait statement.
Once the program waits,you can use it's functions.
<syntaxhighlight lang="runbasic">run "someProgram.bas",#handle
render #handle ' this runs the program until it waits
' both the parent and child are running
' --------------------------------------------------------
' You can also call a function in the someProgram.bas program.
' For example if it had a DisplayBanner Funciton.
#handle DisplayBanner("Welcome!")</syntaxhighlight>
==={{header|Visual Basic .NET}}===
{{trans|C#}}
<syntaxhighlight lang="vbnet">Module Module1
Sub Fork()
Console.WriteLine("Spawned Thread")
End Sub
Sub Main()
Dim t As New System.Threading.Thread(New Threading.ThreadStart(AddressOf Fork))
t.Start()
Console.WriteLine("Main Thread")
t.Join()
End Sub
End Module</syntaxhighlight>
=={{header|Batch File}}==
While you cannot fork into asynchronous subroutines conventionally, there are workarounds involving the <code>start</code> command.
<syntaxhighlight lang="dos">
@echo off
if "%1" neq "" goto %1 || echo Not a valid subroutine
echo Starting mySubroutine1
start "" "%~n0" mySubroutine1
echo.
echo Starting mySubroutine2 6 3
start "" "%~n0" mySubroutine2 6 3
echo.
echo Starting mySubroutine3
start "" "%~n0" mySubroutine3
echo.
:: We wait here for the subroutines to run, but they are running asynchronously
timeout /t 1
for /l %%i in (1,1,3) do (
for /f "tokens=*" %%j in (output%%i.txt) do (
set output%%i=%%j
del output%%i.txt
)
)
echo.
echo.
echo Return values
echo ----------------------------
echo mySubroutine1: %output1%
echo mySubroutine2: %output2%
echo mySubroutine3: %output3%
pause>nul
exit
:mySubroutine1
echo This is the result of subroutine1 > output1.txt
exit
:mySubroutine2
set /a result=%2+%3
echo %result% > output2.txt
exit
:mySubroutine3
echo mySubroutine1 hasn't been run > output3.txt
if exist output1.txt echo mySubroutine1 has been run > output3.txt
exit
</syntaxhighlight>
Output:
<pre>
Starting mySubroutine1
Starting mySubroutine2 6 3
Starting mySubroutine3
Waiting for 0 seconds, press a key to continue ...
Return values
----------------------------
mySubroutine1: This is the result of subroutine1
mySubroutine2: 9
mySubroutine3: mySubroutine1 has been run
</pre>
=={{header|C}}==
{{libheader|POSIX}}<syntaxhighlight lang="c">#include <stdio.h>
#include <unistd.h>
#include <sys/wait.h>
#include <err.h>
int main()
{
usleep(10000);
printf("\tchild process: done\n");
} else if (pid < 0) {
err(1, "fork error");
} else {
printf("waiting for child %d...\n", (int)pid);
printf("child %d finished\n", (int)wait(0));
}
}</syntaxhighlight>output<syntaxhighlight lang="text">waiting for child 3604...
child process: done
child 3604 finished</syntaxhighlight>
=={{header|C sharp|C#}}==
<syntaxhighlight lang="csharp">using System;
using System.Threading;
namespace Fork {
class Program {
static void Fork() {
Console.WriteLine("Spawned Thread");
}
static void Main(string[] args) {
Thread t = new Thread(new ThreadStart(Fork));
t.Start();
Console.WriteLine("Main Thread");
t.Join();
Console.ReadLine();
}
}
}</syntaxhighlight>
=={{header|C++}}==
Line 55 ⟶ 291:
{{libheader|POSIX}}
<syntaxhighlight lang="cpp">#include<iostream>
#include<unistd.h>
Line 77 ⟶ 312:
return 0;
}</syntaxhighlight>
=={{header|Clojure}}==
Through its Java interop capabilities, Clojure has full access to the JRE's process creation and control facilities. The ''clojure.java.shell'' API (in Clojure 1.2; there's an equivalent in 1.1 ''clojure.contrib.shell'') uses these facilities to provide a convenient way of running a shell command in a separate process, providing its arguments, input, environment, and working dir as necessary, and capturing the process's return code and its stdout and stderr output.
<syntaxhighlight lang="clojure">(require '[clojure.java.shell :as shell])
(shell/sh "echo" "foo") ; evaluates to {:exit 0, :out "foo\n", :err ""}</syntaxhighlight>
Though this starts a separate process, the code in ''shell/sh'' blocks until the process completes. We can get other stuff done in the meantime by running the function in a separate thread with the core function ''future''. Suppose we want to find files named "needle.*" in a large directory tree ''haystack'', and do other stuff while the search proceeds. Using the Unix-like command ''find'' the code would look something like
<syntaxhighlight lang="clojure">(let [search (future (shell/sh "find" "." "-name" "needle.*" :dir haystack))]
(while (and (other-stuff-to-do?) (not (future-done? search)))
(do-other-stuff))
(let [{:keys [exit out err]} @search]
(if (zero? exit)
(do-something-with out)
(report-errors-in err))))</syntaxhighlight>
=={{header|COBOL}}==
Using libc fork
{{works with|GnuCOBOL}}
<syntaxhighlight lang="cobol"> identification division.
program-id. forking.
data division.
working-storage section.
01 pid usage binary-long.
procedure division.
display "attempting fork"
call "fork" returning pid
on exception
display "error: no fork linkage" upon syserr
end-call
evaluate pid
when = 0
display " child sleeps"
call "C$SLEEP" using 3
display " child task complete"
when < 0
display "error: fork result not ok" upon syserr
when > 0
display "parent waits for child..."
call "wait" using by value 0
display "parental responsibilities fulfilled"
end-evaluate
goback.
end program forking.</syntaxhighlight>
{{out}}
<pre>prompt$ cobc -xj forking.cob
attempting fork
parent waits for child...
child sleeps
child task complete
parental responsibilities fulfilled</pre>
=={{header|Common Lisp}}==
Line 103 ⟶ 379:
{{works with|SBCL}}
<
(cond
((zerop pid) (write-line "This is the new process."))
((plusp pid) (write-line "This is the original process."))
(t (error "Something went wrong while forking."))))</
=={{header|D}}==
<syntaxhighlight lang="d">import core.thread;
import std.stdio;
void main() {
new Thread({
writeln("Spawned thread.");
}).start;
writeln("Main thread.");
}</syntaxhighlight>
{{out}}
<pre>Main thread.
Spawned thread.</pre>
=={{header|DCL}}==
In OpenVMS DCL, spawning a subprocess creates a partially independent process. The parent and child processes share certain pooled quotas, certain shared resources, and if the parent process is deleted then the child process is too automatically.
<syntaxhighlight lang="dcl">$! looper.com procedure
$ i = 10
$ loop:
$ show time
$ wait 'p1
$ i = i - 1
$ if i .gt. 0 then $ goto loop</syntaxhighlight>
{{out}}
<pre>$ spawn /nowait /notify @looper 0::2 ! up to 8 parameters are allowed
%DCL-S-SPAWNED, process DAVID_51258 spawned ! random number suffix assigned
$
4-JUN-2015 13:13:50
show default5 13:13:52 ! display anomaly due to parent and child overwriting output
4-JUN-2015 13:13:54
USER_ROOT:[DAVID]
$
4-JUN-2015 13:13:57
4-JUN-2015 13:13:59
Interrupt ! ctrl-c is the interrupt character; all child processes are deleted immediately
$
Subprocess DAVID_51258 has completed
$</pre>
To create a more independent process requires a privilege, e.g. detach. There isn't a mechanism for passing parameters to the detached process, so we embed them in a jacket procedure (possibly created dynamically).
<syntaxhighlight lang="dcl">$! fork.com procedure
$ set noverify ! detached processes have verify on by default which clutters up the output log file
$ @looper 0::2</syntaxhighlight>
{{out}}
<pre>$ run /detach sys$system:loginout /input = fork /output = fork
%RUN-S-PROC_ID, identification of created process is 23A4195C
$ stop/id=23A4195C ! rather than just waiting the 10 loop iterations
$ type fork.log
$! fork.com procedure
$ set noverify
4-JUN-2015 13:35:47
4-JUN-2015 13:35:49
4-JUN-2015 13:35:51
4-JUN-2015 13:35:53
4-JUN-2015 13:35:55
4-JUN-2015 13:35:57</pre>
=={{header|Delphi}}==
{{libheader| System.Threading}}
{{Trans|C#}}
<syntaxhighlight lang="delphi">
program Fork_app;
{$APPTYPE CONSOLE}
uses
System.Threading;
procedure Fork;
begin
Writeln('Spawned Thread');
end;
var
t: ITask;
begin
t := TTask.Run(fork);
Writeln('Main Thread');
TTask.WaitForAll(t);
Readln;
end.</syntaxhighlight>
=={{header|Elixir}}==
<syntaxhighlight lang="elixir">defmodule Fork do
def start do
spawn(fn -> child end)
IO.puts "This is the original process"
end
def child, do: IO.puts "This is the new process"
end
Fork.start</syntaxhighlight>
{{out}}
<pre>
This is the original process
This is the new process
</pre>
=={{header|Erlang}}==
Then you can compile your code and execute it:
=={{header|Factor}}==
This works only in the terminal, if used from the UI the child process won't print.
<syntaxhighlight lang="factor">USING: unix unix.process ;
[ "Hello form child" print flush 0 _exit ] [ drop "Hi from parent" print flush ] with-fork</syntaxhighlight>
=={{header|Fexl}}==
There are many levels at which I can address this task. I'll start from the lowest possible level:
<syntaxhighlight lang="fexl">fork \pid
print "pid = ";print pid;nl;
</syntaxhighlight>
{{out}}
<pre>
pid = 10077
pid = 0
</pre>
The child process prints the 0, and the parent process prints the pid of that child, which in this case happened to be 10077.
At the next level up, we can define a "spawn" function which makes it easy to fork a child process and interact with its stdin, stdout, and stderr:
<syntaxhighlight lang="fexl">
# (spawn child_fn next)
# Fork the child function as a process and return its pid, stdin, stdout, and
# stderr.
\spawn =
(
### Use error-checking versions of system routines
\pipe =
(\next
pipe \status\read\write
long_lt status 0 (die "pipe failed");
next read write
)
\dup2 =
(\oldfd\newfd\next
dup2 oldfd newfd \status
long_lt status 0 (die "dup2 failed");
next
)
\fdopen =
(\fd\mode\next
fdopen fd mode next;
die "fdopen failed"
)
\fork =
(\next
fork \pid
long_lt pid 0 (die "fork failed");
next pid
)
# Now here's the spawn function itself.
\child_fn\next
# First flush the parent's stdout and stderr to avoid any pending output
# accidentally getting pushed into the child's input. I've noticed this
# can happen when your script output is sent to a file or pipe instead of
# a console.
get_stdout \fh fflush fh \_
get_stderr \fh fflush fh \_
# Now create a series of pipes, each with a read and write side.
pipe \r_in\w_in
pipe \r_out\w_out
pipe \r_err\w_err
fork \pid
long_eq pid 0
(
# Child process.
# Duplicate one side of each pipe into stdin, stdout, and stderr
# as appropriate.
dup2 r_in 0;
dup2 w_out 1;
dup2 w_err 2;
# Close unused file handles. They're all unused because we duped the
# ones we need. Also, we must close w_in or the child hangs waiting
# for stdin to close.
close r_in; close w_in;
close r_out; close w_out;
close r_err; close w_err;
# Now run the child function, which can use stdin, stdout, and stderr
# normally.
child_fn
)
(
# Parent process. Open the opposite side of each pipe into three new
# file handles.
fdopen w_in "w" \child_in
fdopen r_out "r" \child_out
fdopen r_err "r" \child_err
# Close unused file handles. We don't close the ones we fdopened
# because they are still in play (i.e. fdopen does not dup).
close r_in;
close w_out;
close w_err;
# Return the child's pid, stdin, stdout, and stderr.
next pid child_in child_out child_err
)
)
</syntaxhighlight>
Next, we define a test_pipe function to test the whole apparatus:
<syntaxhighlight lang="fexl">
\test_pipe =
(\next
print "== test_pipe";nl;
### Handy
# Echo entire contents of stream fh to stdout.
\file_print ==
(\fh\next
fgetc fh \ch
long_lt ch 0 next;
putchar ch;
file_print fh next
)
# Show a stream with a descriptive label.
\show_stream =
(\label\fh\next
print "[ ";print label;print ":";nl;
file_print fh;
print "]";nl;
next
)
### Here is a child function to try with spawn.
\child_fn =
(\next
print "Hello from child.";nl;
get_stdin \stdin
show_stream "input from parent" stdin;
print "Good bye from child.";nl;
die "Oops the child had an error!";
next
)
# Spawn the child.
spawn child_fn \pid\child_in\child_out\child_err
# Now we can communicate with the child through its three file handles.
print "Hello from parent, child pid = ";print pid;print ".";nl;
# Say something to the child.
(
# Override print routines for convenience.
\print = (fwrite child_in)
\nl = (print NL)
# Start talking.
print "Hello child, I am your parent!";nl;
print "OK, nice talking with you.";nl;
);
print "The parent is now done talking to the child.";nl;
# Now show the child's stdout and stderr streams.
show_stream "output from child" child_out;
show_stream "error from child" child_err;
# Wait for child to finish.
wait \pid\status
# LATER shift and logical bit operators
# LATER WEXITSTATUS and other wait macros
\status = (long_div status 256)
print "Child ";print pid;print " exited with status ";
print status;print ".";nl;
print "Good bye from parent.";nl;
print "test_pipe completed successfully.";nl;
next
)
</syntaxhighlight>
Finally we call the test function:
<syntaxhighlight lang="fexl">test_pipe;</syntaxhighlight>
{{out}}
<pre>
== test_pipe
Hello from parent, child pid = 10391.
The parent is now done talking to the child.
[ output from child:
Hello from child.
[ input from parent:
Hello child, I am your parent!
OK, nice talking with you.
]
Good bye from child.
]
[ error from child:
Oops the child had an error!
]
Child 10391 exited with status 1.
Good bye from parent.
test_pipe completed successfully.
</pre>
=={{header|Furor}}==
<syntaxhighlight lang="furor">
#g
."Kezd!\n"
§child fork sto childpid
@childpid wait
@childpid ."child pid ez volt: " printnl
end
child: ."Én a child vagyok!\n"
#d 3.14 printnl
2 sleep
end
{ „childpid” }
</syntaxhighlight>
{{out}}
<pre>
Kezd!
Én a child vagyok!
+3.14000000000000
child pid ez volt: 2123
</pre>
=={{header|Peri}}==
<syntaxhighlight lang="Peri">
###sysinclude standard.uh
###sysinclude system.uh
#g
."Start!\n"
§child fork sto childpid
@childpid wait
@childpid ."This was the child pid: " printnl
end
child: ."I am the child!\n"
#d 3.14 printnl
2 sleep
end
{ „childpid” }
</syntaxhighlight>
{{out}}
<pre>
Start!
I am the child!
+3.14000000000000
This was the child pid: 6261
</pre>
=={{header|Go}}==
This program prints its own pid, then runs a copy of itself if given any argument on the command line. When it does so, it prints the pid of the child process it started. Output should show this pid matching the child's self reported pid.
Note that on Unix like systems <code>os.StartProcess</code> is a wrapper around <code>syscal.ForkExec</code> (which as the name implies, safely calls <code>fork</code> and <code>exec</code> system calls).
The [https://golang.org/pkg/os/exec <code>os/exec</code>] package offers a higher level interface and may be simpler in some situations.
For the purpose of this task though, there is little difference.
<syntaxhighlight lang="go">package main
import (
"fmt"
"os"
)
func main() {
fmt.Printf("PID: %v\n", os.Getpid())
if len(os.Args) < 2 {
fmt.Println("Done.")
return
}
cp, err := os.StartProcess(os.Args[0], nil,
&os.ProcAttr{Files: []*os.File{nil, os.Stdout}},
)
if err != nil {
fmt.Println(err)
}
// Child process running independently at this point.
// We have its PID and can print it.
fmt.Printf("Child's PID: %v\n", cp.Pid)
if _, err = cp.Wait(); err != nil {
fmt.Println(err)
}
}</syntaxhighlight>
{{out}}
<pre>PID: 28044
Child's PID: 28045
PID: 28045
Done.</pre>
=={{header|Groovy}}==
Like Java, Groovy controls the standard I/O streams of its child processes. Unlike Java, Groovy provides convenience methods on the Process class to make this burden somewhat easier to manage. This sample code launches the child process and then ties that process's regular and error output streams into the Groovy program's own such streams. This allows us to verify simply that the parent and child processes are running independently.
For the subprocess this example uses Cygwin's bash shell and commands running under MS Windows.
<syntaxhighlight lang="groovy">println "BEFORE PROCESS"
Process p = Runtime.runtime.exec('''
C:/cygwin/bin/sh -c "
/usr/bin/date +'BEFORE LOOP: %T';
for i in 1 2 3 4 ; do
/usr/bin/sleep 1;
/usr/bin/echo \$i;
done;
/usr/bin/date +'AFTER LOOP: %T'"
''')
p.consumeProcessOutput(System.out, System.err)
(0..<8).each {
Thread.sleep(500)
print '.'
}
p.waitFor()
println "AFTER PROCESS"</syntaxhighlight>
Output:
<pre>BEFORE PROCESS
BEFORE LOOP: 12:36:07
..1
..2
..3
..4
AFTER LOOP: 12:36:11
AFTER PROCESS</pre>
=={{header|Haskell}}==
<syntaxhighlight lang="haskell">import System.Posix.Process
main = do
forkProcess (putStrLn "This is the new process")
putStrLn "This is the original process"</syntaxhighlight>
=={{header|HicEst}}==
<syntaxhighlight lang="hicest">SYSTEM( RUN )
WRITE(Messagebox='?Y', IOStat=ios) "Another Fork?"
IF(ios == 2) ALARM(999) ! quit immediately
! assume this script is stored as 'Fork.hic'
SYSTEM(SHell='Fork.hic')
BEEP("c e g 'c")
WRITE(Messagebox="!") "Waiting ..."
ALARM(999) ! quit immediately </syntaxhighlight>
=={{header|Icon}} and {{header|Unicon}}==
<syntaxhighlight lang="icon">procedure main()
if (fork()|runerr(500)) = 0 then
write("child")
else {
delay(1000)
write("parent")
}
end</syntaxhighlight>
Notes:
* Fork should not fail. If an error 500 is generated there is a problem.
* Fork is not supported under windows. Multitasking should be used instead.
=={{header|J}}==
This example works by calling fork in a shared object library of Ubuntu 14.04.1 LTS . The verb given to adverb Fork evaluates in the child process.
<syntaxhighlight lang="j">
load'dll'
Fork =: (('Error'"_)`('Parent'"_)`)(@.([: >: [: * '/lib/x86_64-linux-gnu/libc-2.19.so __fork > x' cd [: i. 0&[))</syntaxhighlight>
The child process explicitly exits remaining as a zombie until the parent terminates.
<pre>
NB. interactive session demonstrating Fork
Time =: 6!:
SLEEP =: 3
sleep =: SLEEP Time
([:exit 0:[:smoutput'child'[sleep)Fork 50 NB. start the child
parent
i._2 3 4 NB. interactive computations continue in the parent process
12 13 14 15
16 17 18 19
20 21 22 23
0 1 2 3
4 5 6 7
8 9 10 11
NB. zzzzz 50 seconds elapse, the child finishes.
child
</pre>
=={{header|Java}}==
{{trans|NetRexx}}
<syntaxhighlight lang="java">
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
public class RFork {
public static void main(String[] args) {
ProcessBuilder pb;
Process pp;
List<String> command;
Map<String, String> env;
BufferedReader ir;
String currentuser;
String line;
try {
command = Arrays.asList("");
pb = new ProcessBuilder(command);
env = pb.environment();
currentuser = env.get("USER");
command = Arrays.asList("ps", "-f", "-U", currentuser);
pb.command(command);
pp = pb.start();
ir = new BufferedReader(new InputStreamReader(pp.getInputStream()));
line = "Output of running " + command.toString() + " is:";
do {
System.out.println(line);
} while ((line = ir.readLine()) != null);
}
catch (IOException iox) {
iox.printStackTrace();
}
return;
}
}
</syntaxhighlight>
{{out}}
<pre>
Output of running [ps, -f, -U, developer] is:
UID PID PPID C STIME TTY TIME CMD
502 74079 1 0 8:13PM ?? 0:00.02 /sbin/launchd
...
502 74047 74045 0 8:13PM ttys000 0:00.05 bash
502 74198 74047 0 8:18PM ttys000 0:00.21 /usr/bin/java -cp .:.. RFork
502 74199 74047 0 8:18PM ttys000 0:00.00 tee data/RForkJ.log
0 74200 74198 0 8:18PM ttys000 0:00.00 ps -f -U developer
...
</pre>
=={{header|Julia}}==
<syntaxhighlight lang="julia">println("Parent running.")
@async(begin sleep(1); println("This is the child process."); sleep(2); println("Child again.") end)
sleep(2)
println("This is the parent process again.")
sleep(2)
println("Parent again.")
</syntaxhighlight>{{output}}<pre>
Parent running.
This is the child process.
This is the parent process again.
Child again.
Parent again.
</pre>
=={{header|Kotlin}}==
{{trans|NetRexx}}
<syntaxhighlight lang="scala">// version 1.1.51
import java.io.InputStreamReader
import java.io.BufferedReader
import java.io.IOException
fun main(args: Array<String>) {
try {
val pb = ProcessBuilder()
val currentUser = pb.environment().get("USER")
val command = listOf("ps", "-f", "U", currentUser)
pb.command(command)
val proc = pb.start()
val isr = InputStreamReader(proc.inputStream)
val br = BufferedReader(isr)
var line: String? = "Output of running $command is:"
while(true) {
println(line)
line = br.readLine()
if (line == null) break
}
}
catch (iox: IOException) {
iox.printStackTrace()
}
}</syntaxhighlight>
Sample output (Ubuntu 14.04):
<pre>
Output of running [ps, -f, U, user1] is:
UID PID PPID C STIME TTY STAT TIME CMD
user1 1401 1387 0 00:13 ? Ss 0:00 init --user
.....
user1 2687 2425 0 00:21 pts/8 Sl+ 0:00 java -jar fork.jar
user1 2699 2687 0 00:21 pts/8 R+ 0:00 ps -f U user1
</pre>
=={{header|Lasso}}==
Lasso is multithreaded by design.
You can fork of an independent thread at anytime using split_thread. The second thread will inherit all local variables declared before it is split.
<syntaxhighlight lang="lasso">local(mydata = 'I am data one')
split_thread => {
loop(2) => {
sleep(2000)
stdoutnl(#mydata)
#mydata = 'Oh, looks like I am in a new thread'
}
}
loop(2) => {
sleep(3000)
stdoutnl(#mydata)
#mydata = 'Aha, I am still in the original thread'
}</syntaxhighlight>
Output:
<pre>I am data one
I am data one
Oh, looks like I am in a new thread
Aha, I am still in the original thread
</pre>
=={{header|LFE}}==
{{trans|Erlang}}
You can run this in the REPL as-is:
<syntaxhighlight lang="lisp">
(defun start ()
(spawn (lambda () (child))))
(defun child ()
(lfe_io:format "This is the new process~n" '()))
</syntaxhighlight>
=={{header|Lua}}==
{{libheader|POSIX}}
<syntaxhighlight lang="lua">local posix = require 'posix'
local pid = posix.fork()
if pid == 0 then
print("child process")
elseif pid > 0 then
print("parent process")
else
error("unable to fork")
end</syntaxhighlight>
=={{header|Mathematica}}/{{header|Wolfram Language}}==
This code will run a standalone Mathematica kernel, putting the result of a command in a temporary file:
<syntaxhighlight lang="mathematica">commandstring = First[$CommandLine] <> " -noprompt -run \"Put[Factorial[20],ToFileName[$TemporaryDirectory,ToString[temp1]]];Quit[]\""
->"MathKernel -noprompt -run \"Put[Factorial[20],ToFileName[$TemporaryDirectory,ToString[temp1]]];Quit[]\""
Run[commandstring]
->0</syntaxhighlight>
=={{header|NetRexx}}==
<syntaxhighlight lang="netrexx">/* NetRexx */
options replace format comments java crossref symbols binary
runSample(arg)
return
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method runSample(arg) private static
do
pb = ProcessBuilder([String ''])
env = pb.environment()
currentuser = String env.get('USER')
command = Arrays.asList([String 'ps', '-f', '-U', currentuser])
pb.command(command)
pp = pb.start()
ir = BufferedReader(InputStreamReader(pp.getInputStream()))
line = String 'Output of running' command.toString() 'is:'
loop label w_ until line = null
say line
line = ir.readLine()
end w_
catch iox = IOException
iox.printStackTrace()
end
return
</syntaxhighlight>
{{out}}
<pre>
Output of running [ps, -f, -U, nrxuser] is:
UID PID PPID C STIME TTY TIME CMD
501 277 1 0 21Aug13 ?? 0:32.05 /sbin/launchd
...
0 366 291 0 21Aug13 ttys001 0:00.02 login -pfl nrxuser /bin/bash -c exec -la bash /bin/bash
501 368 366 0 21Aug13 ttys001 0:00.16 -bash
501 72276 368 0 6:28PM ttys001 0:00.23 /usr/bin/java -cp .:.. RFork
501 72277 368 0 6:28PM ttys001 0:00.00 tee data/RFork.log
0 72278 72276 0 6:28PM ttys001 0:00.00 ps -f -U nrxuser
0 380 291 0 21Aug13 ttys002 0:00.02 login -pfl nrxuser /bin/bash -c exec -la bash /bin/bash
...
</pre>
=={{header|NewLISP}}==
<syntaxhighlight lang="newlisp">(let (pid (fork (println "Hello from child")))
(cond
((nil? pid) (throw-error "Unable to fork"))
('t (wait-pid pid))))</syntaxhighlight>
=={{header|Nim}}==
<syntaxhighlight lang="nim">import posix
var pid = fork()
if pid < 0:
echo "Error forking a child"
elif pid > 0:
echo "This is the parent process and its child has id ", pid, '.'
# Further parent stuff.
else:
echo "This is the child process."
# Further child stuff.</syntaxhighlight>
{{out}}
<pre>This is the parent process and its child has id 8506.
This is the child process.</pre>
=={{header|OCaml}}==
<
let pid = Unix.fork ();;
if pid > 0 then
print_endline "This is the original process"
else
print_endline "This is the new process";;</
=={{header|ooRexx}}==
===version 1 using REPLY===
<syntaxhighlight lang="oorexx">sub=.fork~new
sub~sub
Call syssleep 1
Do 3
Say 'program ' time()
Call syssleep 1
End
::class fork
:: method sub
Reply
Do 6
Say 'subroutine' time()
Call syssleep 1
End</syntaxhighlight>
{{out}}
<pre>subroutine 10:53:27
program 10:53:28
subroutine 10:53:29
program 10:53:35
subroutine 10:53:38
program 10:53:40
subroutine 10:53:40
subroutine 10:53:41
subroutine 10:53:42</pre>
===version 2 using START===
<syntaxhighlight lang="oorexx">sub=.fork~new
sub~start('start_working')
Call syssleep 1
Do 3
Say 'program ' time()
Call syssleep 1
End
::class fork
:: method start_working
Do 6
Say 'subroutine' time()
Call syssleep 1
End</syntaxhighlight>
{{out}}
<pre>subroutine 14:55:10
program 14:55:11
subroutine 14:55:11
subroutine 14:55:12
program 14:55:12
program 14:55:13
subroutine 14:55:13
subroutine 14:55:14
subroutine 14:55:15</pre>
=={{header|Oz}}==
Mozart's support for distributed programming is quite unique. We can send code accross the network and share data by lexical scoping. It doesn't matter whether we create the process on the local machine (as in this example) or on some remote computer as long as we have ssh access (or some similar method) and Mozart is installed.
<syntaxhighlight lang="oz">declare
ParentVar1 = "parent data"
ParentVar2
functor RemoteCode
export
result:Result
import QTk at 'x-oz://system/wp/QTk.ozf'
define
Result
%% Show a simple window. When it is closed by the user, set Result.
Window =
{QTk.build
td(action:proc {$} Result = 42 end %% on close
label(text:"In child process: "#ParentVar1))} %% read parent process variable
{Window show}
!ParentVar2 = childData %% write to parent process variable
{Wait Result}
end
%% create a new process on the same machine
RM = {New Remote.manager init(host:localhost)}
%% execute the code encapsulated in the given functor
RemoteModule = {RM apply(RemoteCode $)}
in
%% retrieve data from child process
{Show RemoteModule.result} %% prints 42
%% exit child process
{RM close}
{Show ParentVar2} %% print "childData"</syntaxhighlight>
=={{header|PARI/GP}}==
This is a PARI implementation which uses <code>fork()</code> via PARI's <code>pari_daemon</code>. Of course <code>fork()</code> could be used directly.
<syntaxhighlight lang="c">void
foo()
{
if (pari_daemon())
pari_printf("Original\n");
else
pari_printf("Fork\n");
}</syntaxhighlight>
=={{header|Perl}}==
Line 138 ⟶ 1,242:
In the child code, you may have to re-open database handles and such.
<
if ($pid = fork()) {
# parent code
Line 162 ⟶ 1,266:
warn '[' . localtime() . "] Unable to fork - $!";
exit(0);
}</
Obviously you could do a Fork in a lot less lines, but this code covers all the bases.
Another example using [http://search.cpan.org/perldoc?Proc::Fork Proc::Fork] module:
<syntaxhighlight lang="perl">use Proc::Fork;
run_fork {
child {
# child code ...
}
parent {
# parent code ...
}
};</syntaxhighlight>
Or:
<syntaxhighlight lang="perl">use Proc::Fork;
# parent code ...
run_fork {
child {
# child code ...
}
};
# parent code continues ...</syntaxhighlight>
More complex example with retries and error handling:
<syntaxhighlight lang="perl">use Proc::Fork;
run_fork {
child {
# child code ...
}
parent {
# parent code ...
}
retry {
# retry code ...
}
error {
# error handling ...
}
};</syntaxhighlight>
=={{header|Phix}}==
Phix has create_thread which creates a separate thread, with its own call stack, but sharing common data (like most fork examples here).<br>
To run something completely independently, use system() or system_exec(), depending on whether you want a shell and/or to wait for a result.
<!--<syntaxhighlight lang="phix">(notonline)-->
<span style="color: #008080;">without</span> <span style="color: #008080;">js</span>
<span style="color: #008080;">procedure</span> <span style="color: #000000;">mythread</span><span style="color: #0000FF;">()</span>
<span style="color: #0000FF;">?</span><span style="color: #008000;">"mythread"</span>
<span style="color: #000000;">exit_thread</span><span style="color: #0000FF;">(</span><span style="color: #000000;">0</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
<span style="color: #004080;">atom</span> <span style="color: #000000;">hThread</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">create_thread</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">routine_id</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"mythread"</span><span style="color: #0000FF;">),{})</span>
<span style="color: #0000FF;">?</span><span style="color: #008000;">"main carries on"</span>
<span style="color: #000000;">wait_thread</span><span style="color: #0000FF;">(</span><span style="color: #000000;">hThread</span><span style="color: #0000FF;">)</span>
<!--</syntaxhighlight>-->
or
<!--<syntaxhighlight lang="phix">(notonline)-->
<span style="color: #008080;">without</span> <span style="color: #008080;">js</span>
<span style="color: #7060A8;">system</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"calc"</span><span style="color: #0000FF;">)</span>
<!--</syntaxhighlight>-->
=={{header|PHP}}==
{{trans|C}}
<
$pid = pcntl_fork();
if ($pid == 0)
Line 176 ⟶ 1,339:
else
echo "ERROR: Something went wrong\n";
?></
=={{header|PicoLisp}}==
<syntaxhighlight lang="picolisp">(unless (fork) # In child process
(println *Pid) # Print the child's PID
(bye) ) # and terminate</syntaxhighlight>
=={{header|PL/I}}==
<syntaxhighlight lang="pl/i">
ATTACH SOLVE (X) THREAD (T5);
</syntaxhighlight>
=={{header|Pop11}}==
{{omit from|PureBasic}}
=={{header|Python}}==
{{works with|Python|2.5}}
<
pid = os.fork()
Line 195 ⟶ 1,369:
# parent code
else:
# child code</
=={{header|R}}==
Two examples. The first is a higher level interface to fork system call. The second is a lower level interface for forking.
<syntaxhighlight lang="r">
p <- parallel::mcparallel({
Sys.sleep(1)
cat("\tChild pid: ", Sys.getpid(), "\n")
TRUE
})
cat("Main pid: ", Sys.getpid(), "\n")
parallel::mccollect(p)
p <- parallel:::mcfork()
if (inherits(p, "masterProcess")) {
Sys.sleep(1)
cat("\tChild pid: ", Sys.getpid(), "\n")
parallel:::mcexit(, TRUE)
}
cat("Main pid: ", Sys.getpid(), "\n")
unserialize(parallel:::readChildren(2))</syntaxhighlight>
Output:
<pre>
Main pid: 331042
Child pid: 331052
$`331052`
[1] TRUE
Main pid: 331042
Child pid: 331054
[1] TRUE
</pre>
=={{header|Racket}}==
Looks like there are two popular things that people do for this task, so here
are both. First, run some subprocess independently of Racket:
<syntaxhighlight lang="racket">
#lang racket
(define-values [P _out _in _err]
(subprocess (current-output-port) (current-input-port) (current-error-port)
(find-executable-path "du") "-hs" "/usr/share"))
;; wait for process to end, print messages as long as it runs
(let loop () (unless (sync/timeout 10 P) (printf "Still running...\n") (loop)))
</syntaxhighlight>
Output:
<pre>
Still running...
Still running...
Still running...
...snip...
15G /usr/share
</pre>
Second, using fork() in its raw form, which is doable in racket, but as unsafe as you'd expect it to be:
<syntaxhighlight lang="racket">
#lang racket
(require ffi/unsafe)
(define fork (get-ffi-obj 'fork #f (_fun -> _int)))
(printf ">>> fork() => ~s\n" (fork))
</syntaxhighlight>
Output:
<pre>
>>> fork() => 23834
>>> fork() => 0
</pre>
=={{header|Raku}}==
(formerly Perl 6)
{{Works with|rakudo|2016.06}}
<syntaxhighlight lang="raku" line>use NativeCall;
sub fork() returns int32 is native { ... }
if fork() -> $pid {
print "I am the proud parent of $pid.\n";
}
else {
print "I am a child. Have you seen my mommy?\n";
}</syntaxhighlight>
{{out}}
<pre>I am the proud parent of 17691.
I am a child. Have you seen my mommy?</pre>
=={{header|REXX}}==
This function '''only''' works with Regina REXX.
<syntaxhighlight lang="rexx">child = fork()</syntaxhighlight>
=={{header|Ruby}}==
<
if pid
# parent code
else
# child code
end</
or
<
# child code
end
# parent code</
=={{header|
This uses the nix(0.15) crate. The code has been tested on Linux, OS X.
<syntaxhighlight lang="rust">use nix::unistd::{fork, ForkResult};
use std::process::id;
fn main() {
match fork() {
Ok(ForkResult::Parent { child, .. }) => {
println!(
"This is the original process(pid: {}). New child has pid: {}",
id(),
child
);
}
Ok(ForkResult::Child) => println!("This is the new process(pid: {}).", id()),
Err(_) => println!("Something went wrong."),
}
}
</syntaxhighlight>output<syntaxhighlight lang="text">This is the original process(pid: 88637). New child has pid: 88651
This is the new process(pid: 88651).
</syntaxhighlight>
=={{header|Scala}}==
{{libheader|Scala}}
===A Linux version===
<syntaxhighlight lang="scala">import java.io.IOException
object Fork extends App {
val builder: ProcessBuilder = new ProcessBuilder()
val currentUser: String = builder.environment.get("USER")
val command: java.util.List[String] = java.util.Arrays.asList("ps", "-f", "-U", currentUser)
builder.command(command)
try {
val lines = scala.io.Source.fromInputStream(builder.start.getInputStream).getLines()
println(s"Output of running $command is:")
while (lines.hasNext) println(lines.next())
}
catch {
case iox: IOException => iox.printStackTrace()
}
}</syntaxhighlight>
===A Windows version===
<syntaxhighlight lang="scala">import java.io.IOException
object Fork extends App {
val command: java.util.List[String] = java.util.Arrays.asList("cmd.exe", "/C", "ECHO.| TIME")
val builder: ProcessBuilder = new ProcessBuilder(command)
try {
val lines = scala.io.Source.fromInputStream(builder.start.getInputStream).getLines()
println(s"Output of running $command is:")
while (lines.hasNext) println(lines.next())
}
catch {
case iox: IOException => iox.printStackTrace()
}
}</syntaxhighlight>
=={{header|Sidef}}==
<syntaxhighlight lang="ruby">var x = 42;
{ x += 1; say x }.fork.wait; # x is 43 here
say x; # but here is still 42</syntaxhighlight>
=={{header|Slate}}==
The following built-in method uses the cloneSystem primitive (which calls fork()) to fork code. The parent and the child both get a socket from a socketpair which they can use to communicate. The cloneSystem is currently unimplemented on windows (since there isn't a fork() system call).<syntaxhighlight lang="slate">p@(Process traits) forkAndDo: b
[| ret |
(ret := lobby cloneSystem)
first ifTrue: [p pipes addLast: ret second. ret second]
ifFalse: [[p pipes clear. p pipes addLast: ret second. b applyWith: ret second] ensure: [lobby quit]]
].</syntaxhighlight>
=={{header|Smalltalk}}==
<
|a|
a := [
Line 234 ⟶ 1,555:
"wait to avoid terminating first the parent;
a better way should use semaphores"
(Delay forSeconds: 10) wait.</
=={{header|Standard ML}}==
<
SOME pid => print "This is the original process\n"
| NONE => print "This is the new process\n";</syntaxhighlight>
=={{header|Symsyn}}==
<syntaxhighlight lang="symsyn">
| parent
ssx 'R child'
wait 'childevent'
'child is running...' []
'child will end...' []
post 'dieevent'
delay 5000
</syntaxhighlight>
<syntaxhighlight lang="symsyn">
| child
post 'childevent'
'I am child...' []
wait 'dieevent'
</syntaxhighlight>
From the command line in Windows :
>SSX parent
{{out}}
<syntaxhighlight lang="symsyn">
SSX Started...
Prog 1 parent Running @ 7/12/2020 13:29:14
1: R child
Prog 2 child Running @ 7/12/2020 13:29:14
2: I am child...
1: child is running...
1: child will end...
Prog 2 child Ended @ 7/12/2020 13:29:14
Prog 1 parent Ended @ 7/12/2020 13:29:19
SSX Ended...
</syntaxhighlight>
=={{header|Tcl}}==
Line 248 ⟶ 1,601:
Fork is one of the primitives used for process creation in Unixy systems. It creates a copy of the process that calls it, and the only difference in internal state between the original and the copy is in the return value from the fork call (0 in the copy, but the pid of the copy in the parent).
The [[SMW::off]][[:Category:Expect|Expect]][[Category:Expect]][[SMW::on]]{{#set:Uses library=Expect}}<!--{{libheader|Expect}}--> package includes a fork. So does the [[SMW::off]][[:Category:TclX|TclX]][[Category:TclX]][[SMW::on]]{{#set:Uses library=TclX}}<!--{{libheader|TclX}}--> package.
Example:
<
# or
package require Tclx
Line 270 ⟶ 1,623:
}
}
}</
In most cases though, one is not interested in spawning a copy of the process one already has, but rather wants a different process. When using POSIX APIs, this has to be done by first forking and then having the child use the exec system call to replace itself with a different program. The Tcl <code>[http://www.tcl.tk/man/tcl8.5/TclCmd/exec.htm exec]</code> command does this fork&exec combination — in part because non-Unix OSs typicallly don't have "make a copy of parent process" as an intermediate step when spawning new processes.
Line 277 ⟶ 1,630:
=={{header|Toka}}==
=={{header|UNIX Shell}}==
{{works with|Bourne Shell}}
<syntaxhighlight lang="bash">i=0
(while test $i -lt 10; do
sleep 1
echo "Child process"
i=`expr $i + 1`
done) &
while test $i -lt 5; do
sleep 2
echo "Parent process"
i=`expr $i + 1`
done</syntaxhighlight>
This uses the operator <tt>&</tt> to run the child process and the parent process at the same time. The output for the next 10 seconds is "Child process" every 1 second, and "Parent process" every 2 seconds. Both processes inherit <tt>i=0</tt>, but each process has its own <tt>i</tt> variable because processes are independent.
The original version of this code used a bash for-loop.
{{works with|bash}}
<syntaxhighlight lang="bash">(for ((i=0;i<10;i++)); do sleep 1; echo "Child process"; done) &
for ((i=0;i<5;i++)); do
sleep 2
echo "Parent process"
done</syntaxhighlight>
=={{header|UnixPipes}}==
Demonstrating a subshell getting forked, and running concurrently with the original process
=={{header|Wart}}==
<syntaxhighlight lang="wart">do (fork sleep.1
prn.1)
prn.2</syntaxhighlight>
=={{header|Wren}}==
{{trans|C}}
The ability to call C library functions such as ''fork'' may be added to Wren-cli in the next release. In the meantime, we embed the following Wren script in a minimal C host (no error checking) to complete this task.
<syntaxhighlight lang="wren">/* Fork.wren */
class C {
foreign static fork()
foreign static usleep(usec)
foreign static wait()
}
var pid = C.fork()
if (pid == 0) {
C.usleep(10000)
System.print("\tchild process: done")
} else if (pid < 0) {
System.print("fork error")
} else {
System.print("waiting for child %(pid)...")
System.print("child %(C.wait()) finished")
}</syntaxhighlight>
<br>
We now embed this in the following C program, compile and run it.
<syntaxhighlight lang="c">#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
#include "wren.h"
void C_fork(WrenVM* vm) {
pid_t pid = fork();
wrenSetSlotDouble(vm, 0, (double)pid);
}
void C_usleep(WrenVM* vm) {
useconds_t usec = (useconds_t)wrenGetSlotDouble(vm, 1);
usleep(usec);
}
void C_wait(WrenVM* vm) {
pid_t pid = wait(NULL);
wrenSetSlotDouble(vm, 0, (double)pid);
}
WrenForeignMethodFn bindForeignMethod(
WrenVM* vm,
const char* module,
const char* className,
bool isStatic,
const char* signature) {
if (strcmp(module, "main") == 0) {
if (strcmp(className, "C") == 0) {
if (isStatic && strcmp(signature, "fork()") == 0) return C_fork;
if (isStatic && strcmp(signature, "usleep(_)") == 0) return C_usleep;
if (isStatic && strcmp(signature, "wait()") == 0) return C_wait;
}
}
return NULL;
}
static void writeFn(WrenVM* vm, const char* text) {
printf("%s", text);
}
char *readFile(const char *fileName) {
FILE *f = fopen(fileName, "r");
fseek(f, 0, SEEK_END);
long fsize = ftell(f);
rewind(f);
char *script = malloc(fsize + 1);
fread(script, 1, fsize, f);
fclose(f);
script[fsize] = 0;
return script;
}
int main(int argc, char **argv) {
WrenConfiguration config;
wrenInitConfiguration(&config);
config.writeFn = &writeFn;
config.bindForeignMethodFn = &bindForeignMethod;
WrenVM* vm = wrenNewVM(&config);
const char* module = "main";
const char* fileName = "Fork.wren";
char *script = readFile(fileName);
wrenInterpret(vm, module, script);
wrenFreeVM(vm);
free(script);
return 0;
}</syntaxhighlight>
{{out}}
Sample output:
<pre>
waiting for child 15274...
child process: done
child 15274 finished
</pre>
=={{header|X86-64 Assembly}}==
===UASM 2.52===
<syntaxhighlight lang="asm">
option casemap:none
windows64 equ 1
linux64 equ 3
ifndef __THREAD_CLASS__
__THREAD_CLASS__ equ 1
if @Platform eq windows64
option dllimport:<kernel32>
CreateThread proto :qword, :qword, :qword, :qword, :dword, :qword
HeapAlloc proto :qword, :dword, :qword
HeapFree proto :qword, :dword, :qword
ExitProcess proto :dword
GetProcessHeap proto
option dllimport:<none>
exit equ ExitProcess
elseif @Platform eq linux64
pthread_create proto :qword, :qword, :qword, :qword
malloc proto :qword
free proto :qword
exit proto :dword
endif
printf proto :qword, :vararg
CLASS thread
CMETHOD createthread
ENDMETHODS
tid dq ?
hThread dq ?
ENDCLASS
METHOD thread, Init, <VOIDARG>, <>
mov rax, thisPtr
ret
ENDMETHOD
METHOD thread, createthread, <VOIDARG>, <>, lpCode:qword, arg:qword
local z:qword,x:qword
mov rbx, thisPtr
assume rbx:ptr thread
mov z, lpCode
mov x, 0
.if arg != 0
mov x, arg
.endif
if @Platform eq windows64
invoke CreateThread, 0, 0, z, x, 0, addr [rbx].tid
.if rax == 0
mov rax, -1
ret
.endif
elseif @Platform eq linux64
invoke pthread_create, addr [rbx].tid, 0, z, x
.if rax != 0
mov rax, -1
ret
.endif
endif
mov [rbx].hThread, rax
assume rbx:nothing
ret
ENDMETHOD
METHOD thread, Destroy, <VOIDARG>, <>
;; We should close all thread handles here..
;; But I don't care. In this example, exit does it for me. :]
ret
ENDMETHOD
endif ;;__THREAD_CLASS__
thChild proto
.data
.code
main proc
local pThread:ptr thread
mov pThread, _NEW(thread)
invoke printf, CSTR("--> Main thread spwaning child thread...",10)
lea rax, thChild
pThread->createthread(rax, 0)
_DELETE(pThread)
;; Just a loop so Exit doesn't foobar the program.
;; No reason to include and call Sleep just for this.. -.-
mov rcx, 20000
@@:
add rax, 1
loop @B
invoke exit, 0
ret
main endp
thChild proc
invoke printf, CSTR("--> Goodbye, World! from a child.... thread.",10)
mov rax, 0
ret
thChild endp
end
</syntaxhighlight>
===NASM===
I've written a subroutine that prints out any positive value. It lives on my desktop and you can't find it on rosetta code.
I've also written a sleep subroutine and you can find that in the Sleep task on this site.
<syntaxhighlight lang="x86asm">
; x86_64 linux nasm
%include "/home/james/Desktop/ASM_LIB/Print.asm"
%include "/home/james/Desktop/ASM_LIB/Sleep.asm"
section .data
parent: db "Parent: "
child: db "Child: "
newLine: db 10
section .text
global _start
_start:
mov rax, 57 ; fork syscall
syscall
cmp rax, 0 ; if the return value is 0, we're in the child process
je printChild
printParent: ; else it's the child's PID, we're in the parent
mov rax, 1
mov rdi, 1
mov rsi, parent
mov rdx, 8
syscall
mov rax, 39 ; sys_getpid
syscall
mov rdi, rax
call Print_Unsigned
mov rax, 1
mov rdi, 1
mov rsi, newLine
mov rdx, 1
syscall
mov rdi, 1 ; sleep so the child process can print befor the parent exits
call Sleep ; you might not see the child output if you don't do this
jmp exit
printChild:
mov rdi, 1
call Sleep ; sleep and wait for parent to print to screen first
mov rax, 1
mov rdi, 1
mov rsi, child
mov rdx, 7
syscall
mov rax, 39 ; sys_getpid
syscall
mov rdi, rax
call Print_Unsigned
mov rax, 1
mov rdi, 1
mov rsi, newLine
mov rdx, 1
syscall
exit:
mov rax, 60
mov rdi, 0
syscall
</syntaxhighlight>
=={{header|XPL0}}==
Works on Raspberry Pi.
<syntaxhighlight lang="xpl0">int Key, Process;
[Key:= SharedMem(4); \allocate 4 bytes of memory common to both processes
Process:= Fork(1); \start one child process
case Process of
0: [Lock(Key); Text(0, "Rosetta"); CrLf(0); Unlock(Key)]; \parent process
1: [Lock(Key); Text(0, "Code"); CrLf(0); Unlock(Key)] \child process
other [Lock(Key); Text(0, "Error"); CrLf(0); Unlock(Key)];
Join(Process); \wait for child process to finish
]</syntaxhighlight>
{{out}}
<pre>
Rosetta
Code
</pre>
=={{header|zkl}}==
{{works with|Unix}}
This just tells the Unix shell to run the process in the background
<syntaxhighlight lang="zkl">zkl: System.cmd("ls &")</syntaxhighlight>
{{out}}
<pre>
0 // return code from the shell, ls has been forked
zkl: 1_2_all_freq.txt ff.zkl lua.zkl rot13.b
2hkprimes.txt fg.zkl lucas-lehmer.zkl rot13.zkl
...
</pre>
{{omit from|JavaScript}}
{{omit from|Maxima}}
{{omit from|TI-83 BASIC|Does not have concurrency or background processes.}}
{{omit from|TI-89 BASIC|Does not have concurrency or background processes.}}
{{omit from|Unlambda|Does not have concurrency or background processes.}}
{{omit from|Retro|No concurrency in the standard VM}}
{{omit from|SAS}}
{{omit from|Stata}}
{{omit from|VBA}}
{{omit from|ZX Spectrum Basic|Does not support multiple processes.}}
| |||