A hack highly depending on the OS, in other words: It works on my Linux x86_64 computer. Your mileage may vary.

> perl -E 'open my $f,"<","/etc/hosts"; system "/bin/ls","-lF",qq[/pro
+c/$$/fd]' < /etc/passwd
total 0
lr-x------ 1 alex users 64 Apr  4 20:17 0 -> /etc/passwd
lrwx------ 1 alex users 64 Apr  4 20:17 1 -> /dev/pts/0
lrwx------ 1 alex users 64 Apr  4 20:17 2 -> /dev/pts/0
lr-x------ 1 alex users 64 Apr  4 20:17 3 -> /etc/hosts
lr-x------ 1 alex users 64 Apr  4 20:17 4 -> pipe:[2099383]

>
[download]

See also:

• https://linux.die.net/man/5/proc
• https://www.kernel.org/doc/Documentation/filesystems/proc.txt

Alexander