TN0089

FUE Login Methodology

CD/OSS
Applications Support

Background: the Fermi Files

Prior to ups/upd v4.x, the Fermi User Environment (FUE) was initialized by the Fermi Files, a suite of shell scripts copied to /usr/local/bin on each system. There were many difficulties with this methodology, including:

• the scripts were bug-prone
• the csh scripts were not consistent with the sh scripts
• the scripts were part of the much larger systools product, hence were difficult to update
• even if systools itself was updated, the new fermi files needed to be copied manually to each /usr/local/bin in a cluster (which rarely happened).
• the fermi files did not work at all in non-interactive mode, so user-developed scripts had to use a different methodology for initialing FUE if the job was not interactive

.login
	/usr/local/etc/fermi .login
	set path
	# lots
	# of
	# code (broken!)
	# inside fermi.login
.cshrc
	/usr/local/etc/fermi.cshrc
	# lots
	#of
	# boken
	# inside
	# fermi.cshrc

Advantages of the New Methodology

When ups/upd were reimplemented in 1999, a new way of initialing FUE became possible. This new methodology eliminates many of the difficulties we've seen in the past:

• The maintainer no longer needs to code both csh and sh scripts. Instead, ups translates table file commands into csh or sh as appropriate. csh and sh remain in-synch with each other.
• Scripts are no longer copied to hard-coded locations. The table files are active cluster-wide as soon as the product is declared 'current'. No extra steps (and no 'root' privilege) required.
• The things that the Fermi Files used to do have been broken up into smaller, more modular pieces, which can be updated independently of the other pieces. This allows much faster turnaround. (When the new methodology was first introduced on fnalu in the summer of 1999, several bugs in the individual subproducts setterm and setxwin were found in the first few days of use. Each bug was fixed, and fnalu upgraded with the new release, within a few hours of being reported and with no intervention by sysadmin staff required. A successful proof-of-concept!).

The new methodology also has the aesthetic feature that, as with the coreFUE products themselves, users need to know only one piece of system-specific information: the SETUPS_DIR. Once you know how to initialize ups, you use setup to initialize everything else about the Fermi environment.

How to Initialize the FUE Environment

In the example below, we assume that the system contains the courtesy links /usr/local/etc/setups.[c]sh. If not, substitute the correct path to $SETUPS_DIR for /usr/local/etc in the examples below. Note that the same techniques can be used in shell scripts.

FUE initialization for csh family:

# # Typical .login snippet, near top of file: # get ups environment, and then setup the login product # if ( -f "/fnal/ups/etc/setups.csh" ) then source "/fnal/ups/etc/setups.csh" if ( { ups exist login } ) then setup login endif endif

# # Typical .cshrc snippet, near top of file: # Get ups environment, and then setup the shrc product # if ( -f "/fnal/ups/etc/setups.csh" ) then source "/fnal/ups/etc/setups.csh" endif if ( { ups exist shrc } ) then setup shrc endif

FUE initialization for sh family:

# # Typical .profile snippet, near top of file: # Get ups environment, and then setup the login product # if [ -f "/fnal/ups/etc/setups.sh" ] then . "/fnal/ups/etc/setups.sh" if ups exist login then setup login fi fi

# # Typical .shrc snippet, near top of file: # Get ups environment, and then setup the shrc product # if [ -f "/fnal/ups/etc/setups.sh" ] then . "/fnal/ups/etc/setups.sh" fi if ups exist shrc then setup shrc fi

A Picture is Worth A Thousand Words...

.login
	/usr/local/etc/setups.csh
setup login
	setup setpath	smaller modules
	setup setterm	easier to
	setup xwin	fix and
	Info	update
	# minimal login code
	# fermi .cshrc
.cshrc
	/usr/local/etc/setups.csh
setup shrc		table-file driven
	#minimal shrc code	so csh & sh always
		in synch

Converting existing systems to the new methodology

systools v6_0 relies on a new product called template_home, which contains the templates for the login scripts which are given to new accounts via cmd adduser (one of the systools utilities). The template_home scripts use the new FUE syntax; therefore, all new accounts created via "cmd adduser" will have the new FUE syntax.

However, existing accounts' login scripts will need to be converted to use the new FUE syntax.

We will soon be providing a product, convert_template_home, to assist in this conversion. It will be documented briefly here, with full documentation in the usual places.