| fai-class(1) | fai-class(1) |
fai-class - define classes using files and scripts.
fai-class [OPTION] DIRECTORY CLASSFILE
This command is only called internally by FAI and not directly by the user.
fai-class executes scripts in DIRECTORY to define classes. All classes are written to CLASSFILE, each class on a separate line. Use absolute paths for both arguments. All scripts or executables matching "^[0-9][0-9]*" (they start with two digits) are executed in alphabetical order. They can define classes by writing the names of the classes to stdout. Classes can be separated by spaces or written one on a line. All lines that start with a "#" are comment lines and are ignored.
Shell scripts that end in ".sh" are sourced and can define classes by setting the variable $newclasses. This is useful for scripts where you can't control stdout. Variables that are defined in these scripts are available to other scripts in DIRECTORY, but they are not exported to the shell that calls fai-class. Those scripts can define variables by writing definitions to the file $LOGDIR/additional.var, which will be sourced in the following task.
All scripts can define additional classes by writing the classes to the file $LOGDIR/additional-classes. These classes are defined after all scripts are executed. This temporary file will be removed after use.
The order of the classes is important because it defines the priority of the classes from low to high. First, the class DEFAULT is defined. Then all scripts are executed to define classes. After that, the classes from the file $LOGDIR/additional-classes are added. Then, all classes in the file with the hostname are added. Then classes defined by the variable ADDCLASSES are used. This variable must be a comma separated list of classes. You can define this variable on the kernel command line.
Finally, the class with the hostname and LAST are defined.
It's important that each line in a file containing a class name ends with a newline. If the newline is missing on the last line of a file, this class can't be added.
The exit code of every script is written to the file status.log in LOGDIR.
In FAI, fai-class is used in the following way:
# fai-class /fai/class /tmp/fai/FAI_CLASSES
Then the list of all classes is assigned to the variable classes.
classes=`cat /tmp/fai/FAI_CLASSES`
This is the script 01alias:
#! /bin/sh
catnc() { # cat but no comment lines
grep -v "^#" $1
}
# echo architecture in upper case
dpkg --print-architecture | tr /a-z/ /A-Z/
uname -s | tr /a-z/ /A-Z/
# all hosts named ant?? use the classes in file anthill
case $HOSTNAME in
ant??) catnc anthill ;;
esac
# a Beowulf cluster; all nodes except the master node
# use classes from file class/atoms
case $HOSTNAME in
atom00) echo BEOWULF_MASTER ;;
atom??) catnc atoms ;;
esac
# if host belongs to class C subnet 123.45.6.0 use class NET_6
case $IPADDR in
123.45.6.*) echo NET_6 ;;
esac
Another EXAMPLE:
The script 24nis:
#! /bin/sh
# add NIS and the NIS domain name if YPDOMAIN is defined
if [ -n "$YPDOMAIN" ];then
echo "NIS $YPDOMAIN" | tr /.a-z-/ /_A-Z_/
else
echo NONIS
fi
You can define classes on the kernel command line by appening this to the kernel:
ADDCLASSES=CLASS1,CLASSX,CLASS3
All class names should be written in uppercase letters (except the class of the hostname). Do not use a dash, use an underscore. Only executable scripts in DIRECTORY are used. CLASSFILE is removed before writing to it. Scripts should not directly write to CLASSFILE. LOGDIR should not be writable for everybody.
This program is part of FAI (Fully Automatic Installation). The FAI homepage is http://fai-project.org.
Written by Thomas Lange <lange@informatik.uni-koeln.de>
| 23 September 2015 | FAI 4 |