$0 inconsistency?

misterperl has asked for the wisdom of the Perl Monks concerning the following question:

Replies are listed 'Best First'.
Re: $0 consistent! by LanX (Saint) on Apr 13, 2022 at 13:47 UTC
It's exactly what you ran, which depends on your current working directory. `d:\tmp>echo print $0 > test.pl d:\tmp>perl test.pl test.pl d:\tmp>cd .. d:\>perl tmp/test.pl tmp/test.pl d:\>perl tmp\test.pl tmp\test.pl d:\>perl tmp/../tmp\test.pl tmp/../tmp\test.pl d:\>` [download] update it's verbatim what was called, even the slashes are not normalized on windows. Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery}	[reply] [d/l]
Re^2: $0 consistent! by misterperl (Friar) on Apr 13, 2022 at 14:13 UTC
OK so when I call it I use perl -wd myscript.pl $0 has no path, and when the crontab calls it, its the full path.. Rolf- you are BRILL! TY the world makes sense again..	[reply]
Re: $0 inconsistency? by choroba (Cardinal) on Apr 13, 2022 at 17:08 UTC
If your tooling depends on the value of $0, note that $0 can be changed. `{ local $0 = 'my program'; print $0; # my program system 'ps'; # <- works even here, at least on my Linux box. } print $0; # Back to the old values. system 'ps'; # ditto` [download] `map{substr$_->[0],$_->[1]\|\|0,1}[\\|\|{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^ARGV,3]`	[reply] [d/l] [select]
Re^2: $0 inconsistency? by Perlbotics (Archbishop) on Apr 13, 2022 at 17:46 UTC
Seems Linux specifc with a 16 byte limit as explained here (Perl 5.14 delta): Assignment to $0 sets the legacy process name with prctl() on Linux	[reply]
Re^3: $0 inconsistency? by mr_mischief (Monsignor) on Apr 13, 2022 at 18:34 UTC
Eh... not quite. Setting `argv[0]` in the process should work on most POSIX systems. That change is an additional thing it does for Linux, and notes the limit for that. This is on a Mac.: `$ perl -e '$0="my really awesome process name"; sleep 60;' & [1] 73413 $ ps PID TTY TIME CMD 70164 ttys002 0:00.05 /opt/local/bin/bash 677 ttys004 0:05.06 /opt/local/bin/bash 73413 ttys004 0:00.03 my really awesome process name` [download]	[reply] [d/l] [select]
Re^2: $0 inconsistency? by misterperl (Friar) on Apr 15, 2022 at 12:59 UTC
tyvm I just copied it in case somewhere else it expected it otherwise: `$_=$0; s\|.+/\|\|;` [download] Cheers thx for the thoughtful reply!	[reply] [d/l]
Re: $0 inconsistency? by Perlbotics (Archbishop) on Apr 13, 2022 at 17:59 UTC
Sometimes, this is useful like (`$me`) for usage info (`usage: $me [ARGS]`). `use strict; use warnings; use Path::Tiny (); my $me = Path::Tiny::path( $0 )->basename(); my $abs_me = Path::Tiny::path( $0 )->realpath(); print "1) original: $0\n"; print "2) short : $me\n"; print "3) long : $abs_me\n";` [download] Result: `rp@linux:local: perl ../me.pl 1) original: ../me.pl 2) short : me.pl 3) long : /home/rp/me.pl` [download]	[reply] [d/l] [select]
Re: $0 inconsistency? $0 doc by Anonymous Monk on Apr 13, 2022 at 13:45 UTC
$0 __FILE__ resolve rel2abs findbin	[reply]
Re^2: $0 inconsistency? $0 doc by LanX (Saint) on Apr 13, 2022 at 13:51 UTC
you should try to check the validity of your links in the preview before submitting. pity, good list otherwise. Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery}	[reply]
Re^3: $0 inconsistency? $0 doc by Anonymous Monk on Apr 13, 2022 at 15:13 UTC
you should try to check the validity of your links in the preview before submitting. pity, good list otherwise. i did check. But i did miss one. Obviously this is a job for computers not fingers on a touchscreen	[reply]
Re^3: $0 inconsistency? $0 doc by misterperl (Friar) on Apr 15, 2022 at 13:02 UTC
TY all experts for your kind and gentle replies. Despite Perl programming since 1995, and hours with Damian, MJD, Larry et al, amazingly, sometimes simple things like this confound me. Expseically little-used ones like this. To all a Happy holiday or at least a great weekend :)	[reply]

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