The Special System Classes

The system provides three special classes in the Solaris 2.5 and later operating environments. They are:

• The sed class

  Provides a method for using sed instructions to edit files upon package installation and removal.

• The awk class

  Provides a method for using awk instructions to edit files upon package installation and removal.

• The build class

  Provides a method to dynamically construct or modify a file using Bourne shell commands.

If there are several files in a package that require special processing that can be fully defined through sed, awk, or sh commands, installation will be faster by using the system classes rather than multiple classes and their corresponding class action scripts.

The sed Class Script

The sed class provides a method to modify an existing object on the target system. The sed class action script executes automatically at installation if a file belonging to class sed exists. The name of the sed class action script should be the same as the name of the file on which the instructions will be executed.

A sed class action script delivers sed instructions in the format shown in Figure 3-1.

Figure 3-1 Format of a sed Class Action Script

# comment, which may appear on any line in the file

!install
# sed(1) instructions which will be invoked during
# installation of the object

[address [,address]] function [arguments]

  . . .

!remove

# sed(1) instructions to be invoked during the removal process

[address [,address]] function [arguments]

Two commands indicate when instructions should be executed. The sed instructions that follow the !install command are executed during package installation and those that follow the !remove command are executed during package removal. It does not matter which order these commands are used in the file.

For more information on sed instructions, see the sed(1) man page. For examples of sed class action scripts, see Chapter 5, Package Creation Case Studies.

The awk Class Script

The awk class provides a method to modify an existing object on the target system. Modifications are delivered as awk instructions in an awk class action script.

The awk class action script is executed automatically at installation if a file belonging to class awk exists. Such a file contains instructions for the awk class script in the format shown in Figure 3-2.

Figure 3-2 Format of an awk Class Action Script

# comment, which may appear on any line in the file

!install

# awk(1) program to install changes

 . . . (awk program)

!remove

# awk1(1) program to remove changes

 . . . (awk program)

Two commands indicate when instructions should be executed. The awk instructions that follow the !install command are executed during package installation, and those that follow the !remove command are executed during package removal. It does not matter in which order these commands are used in the file.

The name of the awk class action script should be the same as the name of the file on which the instructions will be executed.

The file to be modified is used as input to awk and the output of the script ultimately replaces the original object. Environment variables may not be passed to the awk command with this syntax.

For more information on awk instructions, see the awk(1) man page.

The build Class Script

The build class creates or modifies a package object file by executing Bourne shell instructions. These instructions are delivered as the package object, which runs automatically at installation if it belongs to the build class.

The name of the build class action script should be the same as the name of the file on which the instructions will be executed, and must be executable by the sh command. The script's output becomes the new version of the file as it is built or modified.

For example, if a package delivers a default file, /etc/randomtable, and if the file does not already exist on the target system, the prototype file entry might be:

e build /etc/randomtable ? ? ?

and the package object, /etc/randomtable, might look like this:

!install
# randomtable builder
if [ -f $PKG_INSTALL_ROOT/etc/randomtable ]; then
		echo "/etc/randomtable is already in place.";
	    else
		echo "# /etc/randomtable" > $PKG_INSTALL_ROOT/etc/randomtable
		echo "1121554	# first random number" >> $PKG_INSTALL_ROOT/etc/randomtable
fi

!remove
# randomtable deconstructor
if [ -f $PKG_INSTALL_ROOT/etc/randomtable ]; then
		# the file can be removed if it's unchanged
		if [ egrep "first random number" $PKG_INSTALL_ROOT/etc/randomtable ]; then
			rm $PKG_INSTALL_ROOT/etc/randomtable;
		fi
fi

See Chapter 5, Package Creation Case Studies, for another example using the build class.