AIX 4.X Hints, Tips, and Reference

Working with /etc/inittab
Manipulating /etc/services
The RS/6000 LED
Manipulating crontab
Manipulating /etc/exports
Bos Install and NIM

Working with /etc/inittab

The inittab file provides the init program with instructions for creating and running initialization processes. The init program reads the inittab file each time init is invoked. The file typically contains instructions for the default initialization, the creation and control of processes at each run level, and the getty command, which controls the activation of terminal lines.

For more detailed information and examples, see the man pages for the appropriate commands.

There are several AIX commands to manipulate the /etc/inittab file without directly editing it. While it is possible to directly edit /etc/inittab, the supported commands for modifying the records in the file are:

lsitab - Lists records in /etc/inittab
chitab - Changes records in /etc/inittab
mkitab - Adds records to /etc/inittab
rmitab - Removes records from /etc/inittab

It is possible to render a system inoperable and recoverable only by network boot by messing up the /etc/inittab file. Be careful!

lsitab { -a | Identifier }

The lsitab command displays a record in the /etc/inittab file. You can display all of the records in the /etc/inittab file, or use the Identifier parameter to display a specific record. The Identifier parameter is a 14-character field that uniquely identifies an object. The -a flag specifies to list all records in the /etc/inittab file.

To list entry 'hardmon' in /etc/inittab:

lsitab hardmon

chitab { [ Identifier ] : [ RunLevel ] : [ Action ] : [ Command ] }

The chitab command changes a record in the /etc/inittab file. The Identifier:Run Level:Action:Command parameter string is the new entry to the /etc/inittab file. You can search for a specific record by using fields in the Identifier portion of the parameter string. The command finds the specified Identifier and changes that record.

mkitab [ -i Identifier ] { [ Identifier ] : [ RunLevel ] : [ Action ] : [ Command ] }

The mkitab command adds a record to the /etc/inittab file. The Identifier:RunLevel:Action:Command parameter string specifies the new entry to the /etc/inittab file. You can insert a record after a specific record using the -i Identifier flag. The command finds the field specified by the Identifier parameter and inserts the new record after the one identified by the -i Identifier flag.

To create entry 'hardmon' in /etc/inittab:

mkitab "hardmon:2:once:/usr/bin/startsrc -s hardmon"

rmitab Identifier

The rmitab command removes an /etc/inittab record. You can specify a record to remove by using the Identifier parameter. The Identifier parameter specifies a field of one to fourteen characters used to uniquely identify an object. If the Identifier field is not unique, the command is unsuccessful.

To remove entry 'hardmon' in /etc/inittab:

rmitab hardmon

BOS Install and NIM tips

The BOS install scripts are found in /usr/lpp/bosinst. The more interesting script is bi_main. This controls almost all of the install process from a CD or if installing over a network, after NIM is out of the way.

One of the more useful install debugging techniques is turning on the bos install -x option so you can see the script commands as they happen. In order to do this, you will have to have access to the front panel key.

The procedure to enable the bos install debug output is as follows: Boot your system in install mode (from CD, Tape, or Network) When the 'c40' led is displayed, turn key to SECURE Wait for the led to display 'eee', then turn key to SERVICE Wait for the led to display 'ddd', then turn key to NORMAL

To do this on an SP system, a bit more setup is involved. The following procedure does not take into account the ability to have more than one version of AIX installed on the SP complex.

Deallocate resources that might be in use: unallnimres
Remove the /tftpboot/spot* files on the boot/install server: rm /tftpboot/spot_*
Get the spot and lpp_source names:
lnsim -t spot (SPOT_NAME) lsnim -t lpp_source (LPPSOURCE_NAME)
Your AIX_LEVEL is everything following the '_' in the spot and lpp_source names.
Edit the /spdata/sys1/install/
/spot/
/usr/lpp/bosinst/bi_main:
- Find the '0xeee' string and change the sleep call after it from 3 seconds to 30 seconds.
- Find the '0xddd' string and change the sleep call after it from 3 seconds to 30 seconds.
- Find the '0xA40' string and add a line below it: 'sleep 30'.
- Save the changes (after backing up the original, of course).
Rebuild your boot images by issuing: nim -o cust -a lpp_source=

Producing Debug Output for NIM BOS Installations

Creating a debug SPOT can be very useful in debugging installation problems. In order to create a debug spot, issue the following commands:

Create debug versions of the network boot images using the check operation from the VSM or the SMIT interfaces or by using the following command:

nim -o check -a debug=yes SPOTNAME
Get the address for entering the debugger using the following command:

lsnim -l SPOTNAME

where SPOTNAME is the name of your SPOT. Write down the enter_dbg address for the client you are going to boot.
Attach a tty to the client system (port 1).
Network boot the machine
After loading the debug SPOT, you will be given the debugger's '>' prompt.

st enter_dbg_value 2
Type g for go and press enter to start the boot process.

g
Use ctrl-S and ctrl-Q to stop and resume the output.
To rebuild your boot images in non-debug mode, use the following command:

nim -o check -a debug=no SPOTNAME

You will continue to get the debugger's prompt for any client booted with this SPOT until you remove debug.

To check the psspspot after PTFs installed:

nim -o sync_roots psspspot
nim -Fo check psspspot

To rebuild the psspspot resource for install:

set all nodes to disk boot:
/usr/lpp/ssp/bin/SDRChangeAttrValues Node bootp_response=disk
run setup_server to deallocate the spot image:
/usr/lpp/ssp/bin/setup_server
remove the spot image:
/usr/sbin/nim -o remove psspspot
set node response to 'install' for desired nodes
/usr/lpp/ssp/bin/SDRChangeAttrValues Node bootp_response=install
run setup_server to recreate the spot image:
/usr/lpp/ssp/bin/setup_server

Manipulating /etc/services

The chservices command adds, deletes, or changes entries in the /etc/services file. These entries are related to known services used in the DARPA Internet and also related to information used by the inetd server. The entries for the inetd server determine how the system handles Internet service requests. It is possible to edit this file directly, but the supported commands to manipulate the file are:

chservices -c - Changes entries in /etc/services
chservices -a - Adds entries to /etc/services
chservices -d - Deactivate entries in /etc/services

For additional information, see the man page for chservices(1).

Manipulating the /etc/exports file

The /etc/exports file controls the access and availability for remote hosts to mount filesystems from a host. It is possible to edit this file directly, but after editing or changing /etc/exports it is necessary to run /usr/bin/exportfs to make changes effective. Supported commands for modifying /etc/exports are:

chnfsexp - Changes the options used to export a directory to NFS clients.
lsnfsexp - Displays the characteristics of directories that are NFS exported.
mknfsexp - Exports a directory to NFS clients.
rmnfsexp - Unexports a directory from NFS clients.
exportfs - Exports and unexports directories to NFS clients.

To remove an NFS export from the /etc/exports file

/usr/sbin/rmnfsexp -d Directory [-f Exports_file] [ -I | -B | -N ]
Example: rmnfsexp /usr/local

To add an NFS export to the /etc/exports file

Example: mknfsexp

To change an NFS export entry in the /etc/exports file

/usr/sbin/chnfsexp -d Directory [ -f Exports_file ] [ -t [ { rw | ro | rm -h HostName [ ,HostName ... ] } ] ] [ -a UID ] [ -r HostName [ , HostName ... ] ] [ -c HostName , HostName ... ] ] [ -s | -n ] [ -I | -B | -N ] [ -P | -p ]
Example: chnfsexp -d /usr -t rw -c host1,host3,host29 -B

To show an NFS export entry in the /etc/exports file

/usr/sbin/lsnfsexp [ -c | -l ] [ Directory ] [-f Exports_file ]
Example: lsnfsexp /usr

To re-export entries in the /etc/exports file

/usr/sbin/exportfs [ -a ] [ -v ] [ -u ] [ -i ] [ -fFile ] [ -oOption [ ,Option ... ] ] [ Directory ]
Example: exportfs -a

The RS/6000 LED

If you have ever booted an RS/6000, you will notice the front of the box has a 3 digit number changing as the thing boots. (Of course you won't see them without additional tools on an SP2 node, but the LED is still there.) These LED codes are not random, but actually indicate what the machine is doing. Numbers in the 100's are generally POST diagnostics running. Numbers above that are AIX specific and will usually be generated from the /sbin/rc.boot script. The LED will go blank at the end of /sbin/rc.boot when control is returned to init. rc.boot is usually the second line of /etc/inittab.

Setting the LED

You can set the LED to any arbitrary value by using the /usr/lib/methods/showled command and supplying a hex value as an argument.
/usr/lib/methods/showled 0x123

Reading the LED

Reading the values can be a bit confusing, especially on older, true 3 digit displays. The newer SP2 nodes and desktops are able to display better. Below are what the hex a-f values will display. 0-9 are what you would expect them to be.

	'A' or 'a' in scripts appears as 'c' on LED display
	'C' or 'c' in scripts appears as 'u' on LED display
	'F' or 'f' is off

	'a'   'b'   'c'   'd'   'e'   'f'
			   _           o
         _     _    |_|   |_    |_     f
	|_     _|          _    |_     f

Some specific LED values and their meanings

611

LED 611 comes from /sbin/rc.boot when the SPOT is not available during network booting. Check that an entry in /etc/exports exists for the filesystem /spdata/sys1/install/\/spot/spot_\/usr and that the host having the problem is listed in the entry. This problem indicates a mismatch in the hostname or address between the booting machine and the SPOT server. Check that name resolution and /etc/hosts are consistent and that the initial and reliable hostnames are set properly in the SDR for an SP node.

Miscellaneous

To reconfigure/recover ethernet adapter problems:
	ifconfig en0 down
	ifconfig en0 detach
	rmdev -d -l en0
	rmdev -d -l ent0
	cfgmgr [ -v ]
	configure the interface using smitty

The 3590 tape device driver (Atape) and the 3494 tape library
device driver can be downloaded from the following site:
index.storsys.ibm.com	(drivers:deepb1u) /devdrvr
as of 05/28/98.

Older versions of bos install has a problem creating a /usr SPOT when the system
is upgraded to a higher level of AIX.  Use the lpp set of the base
installed AIX level on the SPOT server.  If impossible to do then
look at the file:  /usr/lpp/bos.sysmgt/nim/methods/c_sh_lib.
Change the lslpp arguments from 'lcIqOu' to 'lcqOu'.

AIX Quick Command Reference

To add a service to crontab:

	. /usr/lpp/ssp/install/bin/ssp_functions
	updcrontab -d 0 filename

Customizing a node with PSSP 2.2 is done by setting the
bootp response to 'customize' and rebooting the node. NOT
by doing a network boot.

mklv	-c <# copies>
	-u <# PPS for alloc>
	-s (separate pvs for alloc)
	-y

chlicense -u <# licenses>

chdev	-l aio0 -P
	-a minservers='1'
	-a maxservers='10'
	-a maxreqs='4096'
	-a kprocprio='39'
	-a autoconfig='available'

chdev -l sys0 -a maxuproc='2048'

NIM update:
	nim -o sync_roots psspspot
	nim -Fo check psspspot

inittab:  fbcheck checks for the /etc/firstboot script and runs it
	during node boot.  It then renames the firstboot script to
	fb_ so it is not rerun.  Use this script to
	customize upon reboot.

Customization of nodes:
    After netinstall of a node, the node must be customized to change
    the network interfaces, add the pssp software if not already on
    the system, configure the switch and hostnames, etc.  The script
    /spdata/sys1/install/pssp/pssp_script is run to do the customization
    of the nodes.  This script uses tftp to transfer two files from
    the control workstation that are used to further customize
    the node.  The two files are /tftpboot/script.cust and
    /tftpboot/tuning.cust.  First the tuning.cust is run, then the
    script.cust script is run.

Files to remove from nodes before install image is made:

	/var/adm/SPlogs/sysman/*
	/etc/fb_*
	/etc/niminfo
	/etc/niminfo.prev
	more...

Things to check after pssp upgrade:
	Check that the /spdata/sys1/install/pssp/pssp_script does not
	have any chmod 777 calls in it.  Change these to 755 if found.

File collection note:

	/usr/lpp/ssp/install/bin/rc.sp runs a script named filec_config
	which attempts to put the password and group files in the 
	user.admin file collection if they are not found to alredy be
	installed.  Therefore the lines for etc/passwd and etc/group and
	their related etc/security files must be in the file collection
	but commented out.