---
title: Temporary Disk Space
---


There are several places where users can temporarily store data.

### Note

Temporary storage locations are not backed up and may be removed without
notice.

## /tmp

Files put in the `/tmp` directory are only accessible on the machine on
which they were created and are automatically wiped everytime the
computer is rebooted. Files may also be deleted with little or no
warning if resources become scarce. However, if you need a large amount
of disk space for a short amount of time, `/tmp` provides a solution
which does not need any staff intervention. Remember that there is no
guarantee that files stored in `/tmp` are safe. Do not use `/tmp` for
data that that is difficult or expensive to re-create.

No special permissions are required to use `/tmp`. To reference your
files using `/tmp`, use '`/tmp`' as the prefix to the name of the file,
for example '`/tmp/myfile`'. If you are storing more than a handful of
files, reduce the clutter by using a subdirectory of /tmp named with
your account name, for example '`/tmp/username/myfile`'.

The limit to the amount of storage a user can take up is the physical
limitation of the partition. However, if `/tmp` is full, editors,
compilers, and many other programs will not work or behave erratically.
To find out how much space is available in /tmp on your system, type
'**df -k /tmp**'. Do not use `/tmp` if less than 30% of the space is
available. Remove files when they are no longer needed.

## /var/tmp, /Users/Shared

The `/var/tmp` directory functions similarly to `/tmp`, however, files
are not automatically removed after the machine is rebooted. This
directory does get erased, however, whenever the workstation needs to be
reinstalled or reconfigured. Otherwise, the same policies that apply to
`/tmp` apply to `/var/tmp`.

The `/Users/Shared` directory functions identically to `/var/tmp`,
except it is only found on our Macintosh computers.

## /var/tmp/scratch

The `/var/tmp/scratch` directory exists on some workstations that have
secondary disks. This directory functions similarly to `/var/tmp`,
however, it does not get erased when the computer is reinstalled or
reconfigured.

## /scratch/public

Directories under `/scratch/public` can be used for projects requiring
large files that are modified frequently. The scratch directories exist
on the file server and not on the local workstations, however if space
becomes limited we may automatically compress/gzip files or (if time
permitting) ask users to either remove or archive files that are no
longer needed in order to make room for other users needs. Files that
are not actively being used and are compressible should be stored in a
compressed format.