Where should run-time unix sockets live on Linux?

Question

I have an application that creates a lot of unix sockets to interact with all the processes it spawns at run time. I thought /run/appname would be a good place for them to live, since from what I've understood, /run should be used for information from apps that's only valid during run-time of the app.

But the I discovered

$ mkdir /run/appname
mkdir: cannot create directory '/run/appname': Permission denied

So why can a normal user not create files in /run? What is it used for? Should I just keep to /tmp?

GergA · Answer 1 · 2013-10-27T19:52:03.023

0

/run is reserved for root/system apps.

1. Contact your system admin and ask him to create a socket file for you

or

2. Put into /tmp or the specific forlder in $HOME/

edited Oct 27 '13 at 19:52

answered Oct 26 '13 at 21:04

GergA

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/usr is a bad idea. User write privileges are going to be meager or likely non-existent. – Duck Oct 27 '13 at 00:31
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And you might consider `/var/tmp/` also. But `/usr` is really a bad idea. Sometimes, it is NFS-mounted read-only! – Basile Starynkevitch Oct 27 '13 at 08:16
Of course, for a user-specific application, consider something under its `$HOME`, perhaps in `$HOME/.cache/` – Basile Starynkevitch Oct 27 '13 at 08:30
Or consider having some `$HOME/.appname` directory (of course replace `.appname` by something appropriate to your application). – Basile Starynkevitch Oct 27 '13 at 08:38
apparently there is /run/user/$user - but when should that be used instead of just /tmp? – user1273684 Nov 08 '13 at 17:41

score 0 · Accepted Answer · answered May 10 '17 at 20:19

You should put them in a subdirectory of $XDG_RUNTIME_DIR if the variable is set. See the XDG Basedir Standard: https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html

If it's not set, there are a few places to consider. Many distributions have systemd (or something) create /run/user/<user-id> when a user logs in, so it might be the best place to start looking if $XDG_RUNTIME_DIR is not set. If that fails I fall back to putting things in /tmp. You might try to create a directory within /tmp named randomly or after the username/id with your application name, chown it to the user of the app, set any appropriate permissions, then put sockets in there.

Where should run-time unix sockets live on Linux?

2 Answers2