File protections (or "modes") control who may or may not use your files.
The means for controlling these protections differ significantly between
NFS and AFS.  Nearly all user directories are now on AFS.  For information
on how file permissions work in AFS, read the stock answer titled "How
permissions work in AFS" under the "AFS" topic.  The remainder of this
answer is specific to protection-handling in the NFS (and UFS)
environments ONLY.

You can control the protections of your files with the 'chmod' ("change
mode") command.

The form of the command is:

	chmod mode filename

...where 'mode' is a file protection mode number (explained below), and
'filename' is the name of the file to change.

The mode consists of three octal digits, representing the access allowed for
yourself, for your 'group', and for everyone (in that order).  The value of
each octal digit represents the type(s) of access that is allowed.  To compute
each digit, add up the weights from this table:

	Type of access			     Weight
	------------------------------------ ------
	ability to read the file		4
	ability to write the file		2
	ability to execute (run) the file	1

So, if you have a file named 'foo' that you want to be readable and writeable
by only you, use this command:

	chmod 600 foo

If you to give other people the ability to read the file, use this command:

	chmod 644 foo

If you change the protection of a directory (instead of a normal file), you
should usually make it executable.  A private directory would have a mode of
700.  A directory that others can read would have a mode of 755.

For an explanation of these permissions, please see the answer "Explanation
of NFS/UFS file permissions" under the "NFS/UFS" topic.