Computer Tips - What permissions should the /tmp folder have and how do I set it?

Date: 2011mar8
OS: Linux

Q.  What permissions should the /tmp folder have and how do I set it?

A.  On a properly set up system

ls -ld /tmp /var/tmp

will yield

drwxrwxrwt. 13 root root 40960 Mar  8 11:47 /tmp/
drwxrwxrwt.  2 root root  4096 Mar  8 01:11 /var/tmp/

If your folders (directories) don't have these permissions, correct them like
this:

chmod a+rwxt /tmp /var/tmp

The t is a special flag for temporary folders.  Chmod's man page says:

The  restricted  deletion  flag  or  sticky  bit is a single bit, whose
interpretation depends on the file type.  For directories, it  prevents
unprivileged  users  from  removing or renaming a file in the directory
unless they  own  the  file  or  the  directory;  this  is  called  the
restricted  deletion  flag  for the directory, and is commonly found on
world-writable directories like /tmp.  For regular files on some  older
systems,  the  bit saves the program's text image on the swap device so
it will load more quickly when run; this is called the sticky bit.