/tmp and /var/tmp

Posted Mar 31, 2011 12:57 UTC (Thu) by Cyberax (✭ supporter ✭, #52523)
In reply to: /tmp and /var/tmp by roblucid
Parent article: Introducing /run

That 100GB were for intermediate data in video processing. They are put in /tmp by default.

And why shouldn't they?

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/tmp and /var/tmp

Posted Mar 31, 2011 17:00 UTC (Thu) by vonbrand (subscriber, #4458) [Link] (7 responses)

Because /tmp is supposed to be off-limits for users, it being the place for system temporaries?

/tmp and /var/tmp

Posted Mar 31, 2011 17:54 UTC (Thu) by Cyberax (✭ supporter ✭, #52523) [Link] (2 responses)

Whiskey Tango Foxtrot?

Sticky bit for directories was specifically invented for the world-writable /tmp. Also, where should user processes store their temporary data (for example, if a user opens a .tgz file in Nautilus)?

/home might be on a slow NFS link, so it's an incorrect answer.

/tmp and /var/tmp

Posted Mar 31, 2011 19:43 UTC (Thu) by vonbrand (subscriber, #4458) [Link] (1 responses)

The user temporary files are supposed to go in /var/tmp

/tmp and /var/tmp

Posted Mar 31, 2011 19:56 UTC (Thu) by martinfick (subscriber, #4455) [Link]

Where do you get that rationale from? The FHS does not think so:

/tmp : Temporary files Purpose

The /tmp directory must be made available for programs that require temporary files. Programs must not assume that any files or directories in /tmp are preserved between invocations of the program. Tip Rationale

IEEE standard P1003.2 (POSIX, part 2) makes requirements that are similar to the above section. Although data stored in /tmp may be deleted in a site-specific manner, it is recommended that files and directories located in /tmp be deleted whenever the system is booted.

FHS added this recommendation on the basis of historical precedent and common practice, but did not make it a requirement because system administration is not within the scope of this standard.

/var/tmp : Temporary files preserved between system reboots Purpose

The /var/tmp directory is made available for programs that require temporary files or directories that are preserved between system reboots. Therefore, data stored in /var/tmp is more persistent than data in /tmp. Files and directories located in /var/tmp must not be deleted when the system is booted. Although data stored in /var/tmp is typically deleted in a site-specific manner, it is recommended that deletions occur at a less frequent interval than /tmp.

/tmp and /var/tmp

Posted Apr 1, 2011 15:55 UTC (Fri) by k8to (guest, #15413) [Link]

If /tmp was not for users, then the sticky bit would not have been added to unix to specifically support /tmp for users.

/tmp and /var/tmp

Posted Apr 1, 2011 17:30 UTC (Fri) by nix (subscriber, #2304) [Link] (2 responses)

Uh, GCC dumps stuff in /tmp if you don't specify -pipe. Is the compiler something normal users shouldn't run now?

(FWIW I too have never heard this before. /tmp is transient: /var/tmp is not. That's all.)

/tmp and /var/tmp

Posted Apr 2, 2011 15:15 UTC (Sat) by vonbrand (subscriber, #4458) [Link] (1 responses)

The compiler is not a "normal user", it is a system program (run by normal users under their UID, thus the sticky bit on /tmp).

/tmp and /var/tmp

Posted Apr 2, 2011 17:11 UTC (Sat) by mpr22 (subscriber, #60784) [Link]

1) I notice you're still not bothering to provide a citation for "/tmp is for the system and off-limits to ordinary applications".

2) In my world, the C compiler is an ordinary user application, so should use filesystems in the manner appropriate to ordinary user applications.