Re: perl -d myprog autostarts - but only in one specific directory

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Re^2: perl -d myprog autostarts - but only in one specific directory by bliako (Monsignor) on Jan 18, 2022 at 15:19 UTC
I can replicate on Linux. With an empty `con` dir in current dir, debugger does not break until program exits. If `./con` is a file, it writes to it and enters some kind of never-ending loop, as you say. `strace perl -d a.pl` shows this: `newfstatat(AT_FDCWD, "con", ..., ...)` Then, if `con` is found, it is opened with `openat(AT_FDCWD, "con", O_RDWR\|O_CREAT\|O_TRUNC\|O_CLOEXEC, 0666)` and it is writing to it. `perl a.pl` does not look for `con` The flag `AT_FDCWD` has the meaning of "relative to current dir", i.e. where you execute from and not where script is located. documentation mentions it: `If there is a TTY, we have to determine who it belongs to before we ca +n proceed. If this is a slave editor or graphical debugger (denoted b +y the first command-line switch being '-emacs'), we shift this off an +d set $rl to 0 (XXX ostensibly to do straight reads). We then determine what the console should be on various systems: Cygwin - We use stdin instead of a separate device. Windows or MSDOS - use con. AmigaOS - use CONSOLE:. VMS - use sys$command. Unix - use /dev/tty.` [download] Question is: why on Unix `con` has a role? And I find this in source of `perl5db.pl`: `elsif ( $^O eq 'dos' or -e "con" or $^O eq 'MSWin32' ) { $console = "con"; }` [download] `-e "con"` short-circuits the Unix check further down (if file or dir "con" exists in current dir): `if( -e '/dev/tty')`. Surely a bug AFAICS. bw, bliako	[reply] [d/l] [select]
Re^3: perl -d myprog autostarts - but only in one specific directory by choroba (Archbishop) on Jan 18, 2022 at 17:27 UTC
> Surely a bug AFAICS. AFAICF = as far as I can fix :-) `map{substr$_->[0],$_->[1]\|\|0,1}[\\|\|{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^ARGV,3]`	[reply] [d/l]
Re^4: perl -d myprog autostarts - but only in one specific directory by bliako (Monsignor) on Jan 18, 2022 at 19:34 UTC
I don't think the fix will work. I made a comment below. Thanks, I did not know it was that simple	[reply]
Re^5: perl -d myprog autostarts - but only in one specific directory by pryrt (Monsignor) on Jan 18, 2022 at 20:05 UTC
Re^6: perl -d myprog autostarts - but only in one specific directory by bliako (Monsignor) on Jan 18, 2022 at 21:35 UTC
Some notes below your chosen depth have not been shown here
Re^2: perl -d myprog autostarts - but only in one specific directory by ibm1620 (Pilgrim) on Jan 18, 2022 at 22:43 UTC
Holy smokes. That was it. I deleted con/ and all is well. Incidentally, I don't see any evidence that anything was written into the directory, which just contained a small perl program whose purpose I no longer recall. Thank you all.	[reply]
Re^2: perl -d myprog autostarts - but only in one specific directory by bliako (Monsignor) on Jan 19, 2022 at 13:35 UTC
I did not know of that CON thingy and your mention let me to investigate it. ++	[reply]


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