Comment 61 for bug 269215

when you have a prompt you can check the pemissions with:
# ls -l /

you'll then see something like:

drwxr-xr-x ....... /tmp

there are three sets of permissions, first the owner of the file/directory then the group then everyone else.
if everyone can write it will read:

drwxrwxrwx .../tmp

you can change permissions with chmod using either letters for the permissions or a numeric code

7 means read, write and execute, 777 means everyone can rwx

doing
# chmod 777 /tmp
should do the trick