In what OS and Perl version set $0 works?

[gmpassos]

I need to know in what OS and Perl versions the resource to set $0 works.

I know that it works on:

  Linux - Perl-5.8.0 ; Perl-5.8.1 ; Perl-5.8.3

And here's a test script:

  $|=1 ;

  print "$0\n" ;
  $0 = 'SET_0_WORKS' ;
  print "$0\n" ;
   
  for(0..1000) {
    sleep(1);
    print ".\n" ;
  }

To test, run it than see if 'SET_0_WORKS' appear is the process list. On Linux we type 'ps aux'.

Thanks in advance.

Also this informations can be added to the Perl docs, since we don't see any list of that there.

UPDATE:
The resource to set $0 is to change the information text of the process (let's say title) in the the process table. So, this is not just to see if $0 = foo works, but to see if the change in that variable appear in the process list. I say that because there are a lot of Windows replies saying that it works!

[Corion]

Does not work on Solaris 2.8, perl, version 5.005_03 built for sun4-solaris, neither started as perl -w tmp.pl nor as ./tmp.pl. This may be due to a kernel setting that (dis)allows setting of $0...

I modified the snippet so I can find the PID more easy for grepping:

#!/usr/bin/perl -w
$|=1 ;

print "$$: $0\n" ;
$0 = 'SET_0_WORKS' ;
print "$0\n" ;

for(0..1000) {
  sleep(1);
  print ".\n" ;
}

Under Windows NT with Perl 5.6.1, it dosen't work, as demerphq already found out.

[castaway]

Works on perl 5.6.1, AIX 4.3.3 and AIX 5.2, does not work on HP-UX 11.0.

C.

[eserte]

See the comment in perlvar about $0 on BSD.

[b10m]

Yup, here are my results:

	OpenBSD	FreeBSD
OS Version	3.4	5.2.1
Perl Version	5.8.0	5.8.0
`ps` shows	perl: SET_0_WORKS (perl)	SET_0_WORKS (perl)
`top` shows	perl	perl

(Have no NetBSD machine, sorry ;-)

[pelagic]

Does not work on cygwin version 2.78.2.9 with Perl 5.6.1 (Win NT 4.00.1381).
Does not work on Win NT 4.00.1381 with Perl 5.005_02.

[Eyck]

What's the use, it doesen't work well even when it does work: (linux,5.6) Try:

perl -le '$0="IT_WORKS";while(1) {}'&

and look at whats on top of top. That's right, 'perl', and not 'IT_WORKS', although ps aux|grep IT_WORKS seems to indicate it works. So now maybe killall IT_WORKS works? Nope, it doesen't. (To make top recognize the change, press 'c', as 'show command line')

Am I missing something?

[Fletch]

On Linux top is probably doing something akin to readlink( "/proc/##/exe" ) to get the process name, which wouldn't be changed by mucking with $0 (or by diddling argv[0] from C) since /proc is comming from the kernel's process table directly.

( Not that that makes it work, but it at least might explain the behavior. )

[rob_au]

Works on Mac OS X 10.3(.3) with Perl versions 5.6.2 and 5.8.1 (shipping default).

[CountZero]

Works on ActiveState Perl v5.8.3 built for MSWin32-x86-multi-thread running on Windows XP Pro.

[Anonymous Monk]

Are you sure? Cause I'm pretty sure sure it doesn't. the process list always shows the executable name. You cannot change this on NT.

[JamesNC]

I am on Win32 XPPro and AS 5.8.3 and it doesn't work for me.

[CountZero]

When running the program I get this output:

x:\ActiveState Komodo 2.5\Mozilla\Perl-1.pl
SET_0_WORKS

So it seems to work on my machine. Well at least it produces the expected output (as was asked to check by the OP), but that doesn't mean it DWIM.

[Anneq]

Works with ActiveState Perl v.5.8.0 on Win2K

UPDATE:

It did what I expected it to, but that was not what you were asking.

Sorry,

Anne

[gmpassos]

I have Win2k here and it doesn't work?! How you see your process table?