@erkin What do these do?
SIGINFO is a kill signal that is triggered with ^T (like how ^C triggers SIGINT) that makes the process spit out information.
A particular program that would greatly benefit from it would be dd, which must be *externally* sent SIGUSR1 to make it print I/O status.
Firmlinks are like symlinks in that they point to a file instead of an inode, but instead of just pointing to a path (valid or not), it points to the file itself, avoiding breakage.
Doors are a special file type (like named pipes or sockets) that allow for simple RPC, eschewing necessity for things like D-Bus for simple IPC operations. A Linux implementation of doors exists but it's abandoned since it was never merged.
@erkin So like a hard link?
Unlike a hard link, it's not a separate file pointing to the same inode, but a special file pointing at a file pointing at an inode instead.
@erkin Would they work on FAT32 or Windows?
@erkin Also finding it hard to find documentation on that.
I don't think any OS other than HURD implements it.
@erkin I meant documentation on it in general, HURD docs would work.
This page explains how HURD's filesystem concept works:
It's got rather novel features.
"I appreciate SDF but it's a general-purpose server and the name doesn't make it obvious that it's about art." - Eugen Rochko