$*PROGRAM-NAME is not assignable / does not change process's name

[p6rt]

Migrated from rt.perl.org#132194 (status was 'open')

Searchable as RT132194$

[p6rt]

From @zoffixznet

Opening a ticket, per https://github.com/perl6/roast/issues/339

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$*PROGRAM-NAME is supposed to be a replacement for Perl 5's $0, but it doesn't work that way.

What I'd expect to work​:

use v6; $*PROGRAM-NAME = 'foo'; say `ps $$`; =output Cannot modify an immutable Str (test.pl)   in block \ at test.pl line 2 What should happen​:

use v5.26; $0 = "foo"; say `ps $$`; __DATA__ # PID TTY STAT TIME COMMAND # 5875 pts/1 S+ 0​:00 foo

[p6rt]

From @geekosaur

On Sun, Oct 1, 2017 at 12​:35 PM, Zoffix Znet \perl6\-bugs\-followup@&#8203;perl\.org wrote​:

$*PROGRAM-NAME is supposed to be a replacement for Perl 5's $0, but it doesn't work that way.

What I'd expect to work​:

use v6; $*PROGRAM-NAME = 'foo';

This is not portable and not reliable --- although it will probably work on the limited set of systems moarvm/rakudo currently run on. But the linked ticket is not quite right either​: even on Unix-likes that support it, the result would be shown by 'ps' as something like 'foo [moarvm]' (exact format will depend on OS and/or 'ps' implementation). This is forced for security-related reasons, and you can't override the process's execname to control the part in brackets.

-- brandon s allbery kf8nh sine nomine associates allbery.b@​gmail.com ballbery@​sinenomine.net unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net

[p6rt]

The RT System itself - Status changed from 'new' to 'open'

[p6rt]

From @AlexDaniel

I wonder if this needs a separate sub or variable instead of adding secret functionality to $*PROGRAM-NAME.

On 2017-10-01 09​:52​:19, allbery.b@​gmail.com wrote​:

On Sun, Oct 1, 2017 at 12​:35 PM, Zoffix Znet \perl6\-bugs\-followup@&#8203;perl\.org wrote​:

$*PROGRAM-NAME is supposed to be a replacement for Perl 5's $0, but it doesn't work that way.

What I'd expect to work​:

use v6; $*PROGRAM-NAME = 'foo';

This is not portable and not reliable --- although it will probably work on the limited set of systems moarvm/rakudo currently run on. But the linked ticket is not quite right either​: even on Unix-likes that support it, the result would be shown by 'ps' as something like 'foo [moarvm]' (exact format will depend on OS and/or 'ps' implementation). This is forced for security-related reasons, and you can't override the process's execname to control the part in brackets.