USS(5) AFS File Reference USS(5)NAMEuss - Provides instructions for the uss add command (deprecated)
CAUTIONS
The uss command suite is currently designed for cells using the
obsolete Authentication Server, and therefore is primarily useful for
sites that have not yet migrated to a Kerberos version 5 KDC. The
Authentication Server and supporting commands will be removed in a
future version of OpenAFS, which may include uss unless someone who
finds it useful converts it to work with a Kerberos version 5 KDC.
DESCRIPTION
The uss template file defines the components of an AFS user account
that the uss add command (or add instruction in a uss bulk input file)
creates. Use the -template argument to the uss add or uss bulk command
to identify the template file.
Summary of Template File Instructions
The template file can include the following instructions, each on its
own line. A more detailed description of each instruction's syntax
follows this list.
A Imposes restrictions on user passwords and authentication attempts.
D Creates a directory.
E Creates a single-line file.
F Creates a file by copying a prototype.
G Defines a directory that is one of a set of parent directories into
which the uss command interpreter evenly distributes newly created
home directories.
L Creates a hard link.
S Creates a symbolic link.
V Creates a volume, mounts it in the file space and sets the ACL on
the mount point.
X Executes a command.
If the template file is empty (zero-length), the uss add command or
"add" instruction in a bulk input file only creates an entry in the
Protection and Authentication Databases, naming them according to the
name specified with the uss add command's -user argument, or in the
bulk input file "add" instruction's username field.
The A Instruction for Setting the Default Treatment of Volumes
The "A" instruction in a uss template file enhances cell security by
imposing the following restrictions on users' password choice and
authentication attempts. For further information on these limits, see
the OpenAFS Administration Guide and the kas setfields reference page.
· Limiting the user's password lifetime. When the lifetime expires,
the user can no longer authenticate using that password, and must
change it.
· Prohibiting the reuse of the user's 20 most recently used
passwords.
· Limiting the number of consecutive times that a user can provide an
incorrect password during authentication, and for how long the
Authentication Server refuses further authentication attempts after
the limit is exceeded (referred to as an account lockout). For
regular user accounts in most cells, the recommended limit is nine
and lockout time is 25 minutes.
The instruction has the following syntax:
A <username> <lifetime> <reuse> <failures> <locktime>
where
A Indicates a security-enhancing instruction. It must be a capital
letter.
<username>
Names the Authentication Database entry on which to impose security
restrictions. Specify the value $USER to read in the username from
the uss add command's -user argument, or from the username field of
an "add" instruction in a bulk input file.
<lifetime>
Sets the number of days after the user's password is changed that
it remains valid. When the password becomes invalid (expires), the
user is unable to authenticate, but has 30 more days in which to
issue the kpasswd command to change the password (after that, only
an administrator can change it).
Specify an integer from the range 1 through 254 to specify the
number of days until expiration, the value 0 to indicate that the
password never expires, or the value $PWEXPIRES to read in the
number of days from the uss add or uss bulk command's -pwexpires
argument. If the "A" instruction does not appear in the template
file, the default is for the user's password never to expire.
<reuse>
Determines whether or not the user can change his or her password
(using the kpasswd or kas setpassword command) to one that is
similar to any of the last twenty passwords. The acceptable values
are "reuse" to allow reuse and "noreuse" to prohibit it. If the
"A" instruction does not appear in the template file, the default
is to allow password reuse.
<failures>
Sets the number of consecutive times the user can provide an
incorrect password during authentication (using the klog command or
a login utility that grants AFS tokens). When the user exceeds the
limit, the Authentication Server rejects further authentication
attempts for the amount of time specified in the <locktime> field.
Specify an integer from the range 1 through 254 to specify the
number of failures permitted, or the value 0 to indicate that there
is no limit to the number of unsuccessful attempts. If the "A"
instruction does not appear in the template file, the default is to
allow an unlimited number of failures.
<locktime>
Specifies how long the Authentication Server refuses authentication
attempts from a user who has exceeded the failure limit set in the
<failures> field.
Specify a number of hours and minutes (hh:mm) or minutes only (mm),
from the range 01 (one minute) through "36:00" (36 hours). The
Authentication Server automatically reduces any larger value to
"36:00" and also rounds up any non-zero value to the next higher
multiple of 8.5 minutes. A value of 0 (zero) sets an infinite
lockout time; an administrator must always issue the kas unlock
command to unlock the account.
The D Instruction for Creating a Directory
The "D" instruction in a uss template file creates a directory. Its
intended use is to create a subdirectory in the user home directory
created by the "V" instruction in the template file.
Any number of "D" instructions can appear in the template file. If any
variables in the instruction take their values from the "V" instruction
(notably, the $MTPT variable), the instruction must follow the "V"
instruction in the file.
Although it is possible to use the "D" instruction to create a
directory on the local disk of the machine where the uss command is
issued, it is not recommended. The preferred method for automated
creation of directories on a local disk is the package program. Two
complications arise if the <pathname> field refers to a local disk
directory:
· The uss command prints a warning message because it cannot
associate an access control list (ACL) with a local disk directory.
It creates the directory nonetheless, and some syntactically
correct value must appear in the instruction's <ACL> field.
· To designate any user other than the issuer as the new directory's
owner, the issuer must log onto the machine as the local superuser
"root". For local disk directories, only the local superuser "root"
is allowed to issue the UNIX chown command that the uss command
interpreter invokes to change the owner from the default value (the
directory's creator, which in this case is the issuer of the uss
command). The issuer must then also use the -admin argument to the
uss add or uss bulk command to authenticate as a privileged AFS
administrator, which is required for creating the Authentication
Database and Protection Database entries that the uss command
interpreter always creates for a new account.
The instruction has the following syntax:
D <pathname> <mode> <owner> <ACL>
where
D Indicates a directory creation instruction. It must be a capital
letter.
<pathname>
Specifies the directory's full pathname. It can include variables.
Specify the read/write path to the directory, to avoid the failure
that results from attempting to create a new directory in a read-
only volume. By convention, the read/write path is indicated by
placing a period before the cell name at the pathname's second
level (for example, /afs/.abc.com). For further discussion of the
concept of read/write and read-only paths through the filespace,
see the reference page for the fs mkmount command.
<mode>
Sets the directory's UNIX mode bits. Acceptable values are the
standard three- or four-digit numbers corresponding to combinations
of permissions. Examples: 755 corresponds to "rwxr-xr-x", and 644
to "rw-r--r--". The first (owner) "x" bit must be turned on to
enable access to a directory.
<owner>
Specifies the username or UNIX user ID (UID) of the user to be
designated the directory's owner in the output from the UNIX "ls
-ld" command. If the directory resides in AFS, place the $UID
variable in this field. If the directory resides on the local disk,
this field must be the username or UID of the uss command's issuer,
unless the issuer is logged in as the local superuser "root".
<ACL>
Sets the ACL on the new directory. It must appear even if the new
directory resides on the local disk rather than in AFS, but is
ignored in that case. Provide one or more paired values, each pair
consisting of an AFS username or group name and the desired
permissions, in that order. Separate the two parts of the pair,
and each pair, with a space. The fs setacl reference page describes
the available permissions.
For an AFS directory, grant all permissions to the directory's
owner at least. Usually that is the new user, in which case the
appropriate value is "$USER all".
It is not possible to grant any permissions to the issuer of the
uss command. As the last step in account creation, the uss command
interpreter automatically deletes that person from any ACLs set
during the creation process.
The E Instruction for Creating a Single-line File
The "E" instruction in a uss template file creates a file by echoing a
specified character string into it. Its intended use is to create files
in the user home directory created by the "V" instruction in the
template file, or in a subdirectory created by a "D" instruction.
Any number of "E" instructions can appear in the template file. If the
file resides in a directory created by a "D" instruction, the "E"
instruction must follow the "D" instruction in the file.
The "E" and "F" instructions have complementary advantages. The
character string echoed into the file by an "E" instruction can be
customized for each user, because it can include the standard variables
for which the uss command interpreter substitutes the values specified
by arguments to the uss add command or fields in a bulk input file add
instruction. In contrast, a file created using the "F" instruction
cannot include variables and so has the same content for all users.
However, a file created by an "E" instruction can be a single line
only, because no carriage returns (newline characters) are allowed in
the character string.
Although it is possible to use the "E" instruction to create a file on
the local disk of the machine where the uss command is issued, it is
not recommended. The preferred method for automated creation of files
on a local disk is the package program. The main complication is that
designating any user other than the issuer as the new file's owner
requires logging onto the machine as the local superuser "root". For
local disk files, only the local superuser "root" is allowed to issue
the UNIX chown command that the uss command interpreter invokes to
change the owner from the default value (the file's creator, which in
this case is the issuer of the uss command). The issuer must then also
use the -admin argument to the uss add or uss bulk command to
authenticate as a privileged AFS administrator, which is required for
creating the Authentication Database and Protection Database entries
that the uss command interpreter always creates for a new account.
The instruction has the following syntax:
E <pathname> <mode> <owner> "<contents>"
where
E Indicates a file creation instruction. It must be a capital letter.
<pathname>
Specifies the file's full pathname. It can include variables.
Specify the read/write path to the file, to avoid the failure that
results from attempting to create a new file in a read-only volume.
By convention, the read/write path is indicated by placing a period
before the cell name at the pathname's second level (for example,
/afs/.abc.com). For further discussion of the concept of read/write
and read-only paths through the filespace, see the reference page
for the fs mkmount command.
<mode>
Sets the file's UNIX mode bits. Acceptable values are the standard
three- or four-digit numbers corresponding to combinations of
permissions. Examples: 755 corresponds to "rwxr-xr-x", and 644 to
"rw-r--r--".
<owner>
Specifies the username or UNIX user ID (UID) of the user to be
designated the file's owner in the output from the UNIX "ls -l"
command. If the file resides in AFS, place the $UID variable in
this field. If the file resides on the local disk, specify the
username or UID of the uss command's issuer; otherwise, the account
creation operation halts immediately.
<contents>
Specifies the one-line character string to write into the new file.
Surround it with double quotes if it contains one or more spaces.
It cannot contain the newline character, but can contain any of the
standard variables, which the command interpreter resolves as it
creates the file.
The F Instruction for Creating a File from a Prototype
The "F" instruction in a uss template file creates a file by copying
the contents of an existing file (the <prototype>) into it. Its
intended use is to create files in the user home directory created by
the "V" instruction in the template file, or in a subdirectory created
by a "D" instruction.
Any number of "F" instructions can appear in the template file. If the
file resides in a directory created by a "D" instruction, the "F"
instruction must follow the "D" instruction in the file.
The "E" and "F" instructions have complementary advantages. A file
created using the "F" instruction has the same content for all users,
whereas a file created by an "E" instruction can be customized for each
user if it includes variables. However, a file created by an "E"
instruction can be a single line only, whereas the prototype file
copied by an "F" instruction can be any length.
Although it is possible to use the "F" instruction to create a file on
the local disk of the machine where the uss command is issued, it is
not recommended. The preferred method for automated creation of files
on a local disk is the package program. The main complication is that
designating any user other than the issuer as the new file's owner
requires logging onto the machine as the local superuser "root". For
local disk files, only the local superuser "root" is allowed to issue
the UNIX chown command that the uss command interpreter invokes to
change the owner from the default value (the file's creator, which in
this case is the issuer of the uss command). The issuer must then also
use the -admin argument to the uss add or uss bulk command to
authenticate as a privileged AFS administrator, which is required for
creating the Authentication Database and Protection Database entries
that the uss command interpreter always creates for a new account.
The instruction has the following syntax:
F <pathname> <mode> <owner> <prototype_file>
where
F Indicates a file creation instruction. It must be a capital letter.
<pathname>
Specifies the full pathname of the file to create, including the
filename. It can include variables.
Specify the read/write path to the file, to avoid the failure that
results from attempting to create a new file in a read-only volume.
By convention, the read/write path is indicated by placing a period
before the cell name at the pathname's second level (for example,
/afs/.abc.com). For further discussion of the concept of read/write
and read-only paths through the filespace, see the reference page
for the fs mkmount command.
<mode>
Sets the file's UNIX mode bits. Acceptable values are the standard
three- or four-digit numbers corresponding to combinations of
permissions. Examples: 755 corresponds to "rwxr-xr-x", and 644 to
"rw-r--r--".
<owner>
Specifies the username or UNIX user ID (UID) of the user to be
designated the file's owner in the output from the UNIX "ls -l"
command. If the file resides in AFS, place the $UID variable in
this field. If the file resides on the local disk, specify the
username or UID of the uss command's issuer; otherwise, the account
creation operation halts immediately.
<prototype_file>
Names the AFS or local disk directory that houses the prototype
file to copy. The prototype file's name must match the final
element in the <pathname> field.
The G Instruction for Even Distribution of Home Directories
The "G" instruction in a uss template file creates a directory as one
of the set of directories from which the uss command interpreter
selects when choosing a new user home directory's parent directory.
More specifically, when the $AUTO variable appears in the <mount_point>
field of a "V" instruction, the command interpreter substitutes for it
the directory defined by a "G" instruction that currently has the
fewest entries.
The instruction's intended use is to distribute user accounts evenly
among several directories, rather than using directories that reflect
divisions such as departmental affiliation. Distributing home
directories in this fashion is useful mainly in very large cells where
storing all user home directories under a single parent directory
potentially slows directory lookup, or where a workplace-based division
results in unevenly sized directories such that some users consistently
experience slower directory lookup than others. See the chapter on uss
in the OpenAFS Administration Guide for more information.
Any number of "G" instructions can appear in the template file. If the
"V" instruction includes the $AUTO variable, it must appear after all
of the "G" instructions in the file.
The instruction has the following syntax:
G <directory>
where
G Indicates an instruction that creates a directory to be considered
as a value for the $AUTO variable. It must be a capital letter.
<directory>
Specifies the directory's name as either a complete pathname or
only the directory name. The choice determines the appropriate
format for the <mount_point> field of a "V" instruction, as
discussed in the following example.
Specify the read/write path to the directory, to avoid the failure
that results from attempting to create a new mount point in a read-
only volume when the $AUTO variable is used in a "V" instruction's
<mount_point> field. By convention, the read/write path is
indicated by placing a period before the cell name at the
pathname's second level (for example, /afs/.abc.com). For further
discussion of the concept of read/write and read-only paths through
the filespace, see the reference page for the fs mkmount command.
The L and S Instructions for Creating a Link
The "L" instruction in a uss template file creates a hard link between
two files, as achieved by the standard UNIX ln command. The "S"
instruction creates a symbolic link between two files, as achieved by
the standard UNIX "ln -s" command. A full explanation of links is
beyond the scope of this document, but the basic effect is to create a
second name for an existing file, enabling access via either name.
Creating a link does not create a second copy of the file.
AFS allows hard links only if the linked files reside in the same
directory, because it becomes difficult to determine which access
control list (ACL) applies to the file if the two copies reside in
directories with different ACLs. AFS allows symbolic links between two
files that reside in different directories, or even different volumes.
The File Server uses the ACL associated with the actual file rather
than the link.
Any number of "L" and "S" instructions can appear in the template file.
If the existing file or link is to reside in a directory created by a
"D" instruction, or if the existing file was created by an "E" or "F"
instruction, the "L" or "S" instruction must follow the "D", "E", or
"F" instruction.
The instructions share the following syntax:
L <existing_file> <link>
S <existing_file> <link>
where
L Indicates a hard link creation instruction. It must be a capital
letter.
S Indicates a symbolic link creation instruction. It must be a
capital letter.
<existing_file>
Specifies the complete pathname of the existing file.
<link>
Specifies the complete pathname of the second name for the file.
Specify the read/write path to the link, to avoid the failure that
results from attempting to create a new link in a read-only volume.
By convention, the read/write path is indicated by placing a period
before the cell name at the pathname's second level (for example,
/afs/.abc.com). For further discussion of the concept of read/write
and read-only paths through the filespace, see the reference page
for the fs mkmount command.
The V Instruction for Creating and Mounting a Volume
The "V" instruction in a uss template file creates a volume on a
specified file server machine and partition and creates an entry for it
in the Volume Location Database (VLDB). It mounts the volume at a
location in the AFS file space that becomes the user's home directory,
then designates the directory's owner and sets its access control list
(ACL).
Only one "V" instruction can appear in the template file, and one must
appear if the template file contains any instructions at all (is not
empty). All other instructions are optional, except that the template
must include "G" instructions if the $AUTO variable appears in it. (The
"V" instruction is not necessarily the first line in the template. If
the template includes the $AUTO variable, then the "G" instructions
which provide values for the variable must precede it in the file.)
The instruction has the following syntax:
V <vname> <server> <partition> <quota> <mount_point> <owner> <ACL>
where
V Indicates a volume creation instruction. It must be a capital
letter.
<name>
Specifies the volume's name. To follow the convention for AFS user
volume names, specify the value "user.$USER". Provide a value for
the $USER variable via the uss add command's -user argument or the
<username> field in the bulk input file add instruction.
<server>
Names the file server machine on which to create the new user's
volume. It is best to provide the fully-qualified hostname (for
example, "fs1.abc.com"), but an abbreviated form is acceptable
provided that the cell's naming service is available to resolve it
at the time the volume is created. To read in the value from the
uss add command's -server argument, specify the value $SERVER.
<partition>
Specifies the partition on which to create the user's volume; it
must be on the file server machine named in the <server> field.
Identify the partition by its complete name (for example, /vicepa)
or use or use one of the following abbreviations.
/vicepa = vicepa = a = 0
/vicepb = vicepb = b = 1
After /vicepz (for which the index is 25) comes
/vicepaa = vicepaa = aa = 26
/vicepab = vicepab = ab = 27
and so on through
/vicepiv = vicepiv = iv = 255
To read in the value from the uss add command's -partition
argument, specify the value $PART.
<quota>
Sets the maximum number of kilobyte blocks the volume can occupy on
the file server machine's disk. Specify an integer constant if all
volumes have the same quota (1024 equals a megabyte), or use one of
the number variables ($1 through $9) to assign different values to
different volumes.
<mount_point>
Creates a mount point for the volume, which serves as the volume's
root directory. Include the $USER variable as part of the pathname
to follow the convention that user home directory names include the
username.
Specify the read/write path to the mount point, to avoid the
failure that results from attempting to create a new mount point in
a read-only volume. By convention, the read/write path is indicated
by placing a period before the cell name at the pathname's second
level (for example, /afs/.abc.com). If the $AUTO variable appears
in this field, the directories named by each "G" instruction
possibly already indicate the read/write path. For further
discussion of the concept of read/write and read-only paths through
the filespace, see the reference page for the fs mkmount command.
<owner>
Specifies the username or UNIX user ID (UID) of the user to be
designated the mount point's owner in the output from the UNIX "ls
-ld" command. To follow the convention for home directory
ownership, place the value $UID in this field.
<ACL>
Sets the ACL on the new directory. Provide one or more paired
values, each pair consisting of an AFS username or group name and
the desired permissions, in that order. Separate the two parts of
the pair, and each pair, with a space. The fs setacl reference page
describes the available permissions.
Grant all permissions to the new user at least. The appropriate
value is "$USER all".
AFS automatically grants the system:administrators group all
permissions as well. It is not possible to grant any permissions to
the issuer of the uss command. As the last step in account
creation, the uss command interpreter automatically deletes that
user from any ACLs set during the creation process.
The X Instruction for Running a Command
The "X" instruction in a uss template file runs the indicated command,
which can be a standard UNIX or AFS command. It can include any
variables from the template file, which the uss command interpreter
resolves before passing the command on to the appropriate other command
interpreter. It must be a single line only, however (cannot contain
carriage returns or newline characters).
Any number of "X" instructions can appear in the template file. If an
instruction manipulates an element created by another instruction, it
must follow that instruction in the file.
The instruction has the following syntax:
X "<command>"
where
X Indicates a command execution instruction. It must be a capital
letter.
<command>
Specifies the command to run. Surround it with double quotes as
shown if it contains one or more spaces. It can contain any
variables from the template file, but not newline characters.
EXAMPLES
The following example A instruction sets a password lifetime of 254
days, prohibits password reuse, limits the number of consecutive failed
authentication attempts to nine and sets the corresponding locktime to
25:30 minutes (which is a multiple of 8.5 minutes). The username is
read in from the -user argument to the uss add command or from the
username field in each "add" instruction in a bulk input file.
A $USER 254 noreuse 9 25:30
The following example "D" instruction creates a directory called public
in a new user's home directory, designates the user as the directory's
owner, and grants him or her all ACL permissions.
D $MTPT/public 0755 $UID $USER all
The following example "E" instruction creates a file in the current
working directory called username.etcp. The contents are an entry
suitable for incorporating into the cell's global /etc/password file.
E $USER.etcp 0644 root "$USER:X:$UID:10:$NAME:$MTPT:/bin/csh"
The following example "F" instruction, appropriate for the ABC
Corporation cell, copies a prototype .login file into the user's home
directory.
F $MTPT/.login 0644 $UID /afs/abc.com/common/uss/skel/.login
In the following example, the State University cell's administrators
have decided to distribute user home directories evenly into three
directories. They define three "G" instructions:
G usr1
G usr2
G usr3
and then put the following value in the <mount_point> field of the "V"
instruction:
/afs/stateu.edu/$AUTO/$USER
Alternatively, if they include the entire directory pathname in the "G"
instruction:
G /afs/stateu.edu/usr1
G /afs/stateu.edu/usr2
G /afs/stateu.edu/usr3
then the <mount_point> field of the "V" instruction specifies only the
following:
$AUTO/$USER
The following example "L" instruction creates a hard link between the
files mail and mbox in the user's home directory.
L $MTPT/mbox $MTPT/mail
The following example "S" instruction, appropriate for the ABC
Corporation cell, links the file Mail/outgoing in the user's home
directory to the file /afs/abc.com/common/mail/outgoing.
S /afs/abc.com/common/mail/outgoing $MTPT/Mail/outgoing
The following example "V" instruction creates a volume called
"user.username" on the /vicepa partition of the specified file server
machine, assigning it a quota of 3000 kilobyte blocks. The mount point
is under /afs/abc.com/usr and matches the username (the value of the
$USER variable). The user owns the home directory and has all access
rights to it. The instruction appears on two lines only for legibility;
it must appear on a single line in the template file.
V user.$USER $SERVER.abc.com /vicepa 3000 \
/afs/abc.com/usr/$USER $UID $USER all
The following example "X" instruction mounts the backup version of the
user's volume at the OldFiles subdirectory.
X "fs mkm /afs/abc.com/usr/$USER/OldFiles user.$USER.backup"
SEE ALSOuss_bulk(5), fs_mkmount(1), uss_add(8)COPYRIGHT
IBM Corporation 2000. <http://www.ibm.com/> All Rights Reserved.
This documentation is covered by the IBM Public License Version 1.0.
It was converted from HTML to POD by software written by Chas Williams
and Russ Allbery, based on work by Alf Wachsmann and Elizabeth Cassell.
OpenAFS 2013-10-09 USS(5)
