Determine if only one instance is running: Difference between revisions

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(Rename Perl 6 -> Raku, alphabetize, minor clean-up)
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return 0;
return 0;
}</lang>
}</lang>

=={{header|C++}}==
===Microsoft Windows===
{{works with|Windows|2000 or later}}
This line needs to be near the top of the file (or in stdafx.h, if you use one.)
<lang cpp>#include <afx.h></lang>

You need a variable of type HANDLE with the same lifetime as your program. Perhaps as a member of your CWinApp object.
<lang cpp>HANDLE mutex;</lang>

At the earliest possible point in your program, you need to initialize it and perform your check. "MyApp" should be a string unique to your application. See [http://msdn2.microsoft.com/en-us/library/ms682411.aspx here] for full details.

<lang cpp>mutex = CreateMutex( NULL, TRUE, "MyApp" );
if ( GetLastError() == ERROR_ALREADY_EXISTS )
{
// There's another instance running. What do you do?
}</lang>

Finally, near the end of your program, you need to close the mutex.
<lang cpp>CloseHandle( mutex );</lang>


=={{header|C sharp|C#}}==
=={{header|C sharp|C#}}==
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}
}
}</lang>
}</lang>

=={{header|C++}}==
===Microsoft Windows===
{{works with|Windows|2000 or later}}
This line needs to be near the top of the file (or in stdafx.h, if you use one.)
<lang cpp>#include <afx.h></lang>

You need a variable of type HANDLE with the same lifetime as your program. Perhaps as a member of your CWinApp object.
<lang cpp>HANDLE mutex;</lang>

At the earliest possible point in your program, you need to initialize it and perform your check. "MyApp" should be a string unique to your application. See [http://msdn2.microsoft.com/en-us/library/ms682411.aspx here] for full details.

<lang cpp>mutex = CreateMutex( NULL, TRUE, "MyApp" );
if ( GetLastError() == ERROR_ALREADY_EXISTS )
{
// There's another instance running. What do you do?
}</lang>

Finally, near the end of your program, you need to close the mutex.
<lang cpp>CloseHandle( mutex );</lang>


=={{header|Clojure}}==
=={{header|Clojure}}==
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(try (new ServerSocket *port* 10 (. InetAddress getLocalHost))
(try (new ServerSocket *port* 10 (. InetAddress getLocalHost))
(catch IOException e (System/exit 0))) ; port taken, so app is already running </lang>
(catch IOException e (System/exit 0))) ; port taken, so app is already running </lang>
=={{header|Delphi}}==
<lang Delphi>program OneInstance;


{$APPTYPE CONSOLE}

uses SysUtils, Windows;

var
FMutex: THandle;
begin
FMutex := CreateMutex(nil, True, 'OneInstanceMutex');
if FMutex = 0 then
RaiseLastOSError
else
begin
try
if GetLastError = ERROR_ALREADY_EXISTS then
Writeln('Program already running. Closing...')
else
begin
// do stuff ...
Readln;
end;
finally
CloseHandle(FMutex);
end;
end;
end.</lang>
=={{header|D}}==
=={{header|D}}==
===Unix Domain Socket===
===Unix Domain Socket===
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}
}
</lang>
</lang>

=={{header|Delphi}}==
<lang Delphi>program OneInstance;

{$APPTYPE CONSOLE}

uses SysUtils, Windows;

var
FMutex: THandle;
begin
FMutex := CreateMutex(nil, True, 'OneInstanceMutex');
if FMutex = 0 then
RaiseLastOSError
else
begin
try
if GetLastError = ERROR_ALREADY_EXISTS then
Writeln('Program already running. Closing...')
else
begin
// do stuff ...
Readln;
end;
finally
CloseHandle(FMutex);
end;
end;
end.</lang>


=={{header|Erlang}}==
=={{header|Erlang}}==
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canopen()
canopen()
</lang>
</lang>



=={{header|Kotlin}}==
=={{header|Kotlin}}==
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}
}
</lang>
</lang>



=={{header|Mathematica}} / {{header|Wolfram Language}}==
=={{header|Mathematica}} / {{header|Wolfram Language}}==
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sleep 60; # then your code goes here</lang>
sleep 60; # then your code goes here</lang>
=={{header|Perl 6}}==
{{works with|rakudo|2018.03}}
An old-school Unix solution, none the worse for the wear:
<lang perl6>my $name = $*PROGRAM-NAME;
my $pid = $*PID;

my $lockdir = "/tmp";
my $lockfile = "$lockdir/$name.pid";
my $lockpid = "$lockfile$pid";
my $havelock = False;

END {
unlink $lockfile if $havelock;
try unlink $lockpid;
}

my $pidfile = open "$lockpid", :w orelse .die;
$pidfile.say($pid);
$pidfile.close;

if try link($lockpid, $lockfile) {
$havelock = True;
}
else {
shell "kill -CONT `cat $lockfile` || rm $lockfile";
if try link($lockfile, $lockpid) {
$havelock = True;
}
else {
die "You can't run right now!";
}
}
note "Got lock!";
unlink $lockpid;</lang>


=={{header|Phix}}==
=={{header|Phix}}==
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(sleep 10)
(sleep 10)
</lang>
</lang>

=={{header|Raku}}==
(formerly Perl 6)
{{works with|rakudo|2018.03}}
An old-school Unix solution, none the worse for the wear:
<lang perl6>my $name = $*PROGRAM-NAME;
my $pid = $*PID;

my $lockdir = "/tmp";
my $lockfile = "$lockdir/$name.pid";
my $lockpid = "$lockfile$pid";
my $havelock = False;

END {
unlink $lockfile if $havelock;
try unlink $lockpid;
}

my $pidfile = open "$lockpid", :w orelse .die;
$pidfile.say($pid);
$pidfile.close;

if try link($lockpid, $lockfile) {
$havelock = True;
}
else {
shell "kill -CONT `cat $lockfile` || rm $lockfile";
if try link($lockfile, $lockpid) {
$havelock = True;
}
else {
die "You can't run right now!";
}
}
note "Got lock!";
unlink $lockpid;</lang>


=={{header|REXX}}==
=={{header|REXX}}==
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}</lang>
}</lang>

=={{header|Sidef}}==
=={{header|Sidef}}==
<lang ruby># For this to work, you need to explicitly
<lang ruby># For this to work, you need to explicitly
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