Re: /run and needing a --rundir for configure

[Paolo Bonzini]

Date: Sun, 08 Sep 2013 12:26:22 -0400
From: Richard Stallman <address@hidden>
To: address@hidden (Karl Berry)
Subject: Re: --rundir for coding standards

    + The directory for installing data files which the programs modify
    + while they run, that pertain to one specific machine, and which need
    + not persist longer than the execution of the program.

Those words are not clear to me.  Are these temp files?
If not, how do they differ from temp files?

Temporary files are stored until their content is consumed, so they are usually tied to a short-running process.  /run is also tied to the lifetime of a process, but usually it is long-running.  For example, it could hold:

* "state" files, like pid files for daemons

* FIFOs and AF_UNIX sockets

Another use for /run is to place mountpoints that are not persistent across reboot, for example removable devices or Hurd-style virtual filesystems (Linux implements them in FUSE, the "filesystem in userspace" module).  Putting them into /run ensures that /mnt (or an equivalent directory under the user's home directory) does not get crowded.

Paolo