The format of the Instructions file in a package archive
is as follows.

Each instruction is a line by itself.  Each instruction consists of a
single character instruction code followed by a number of fields.  Fields
do not contain spaces.

Various standard kinds of fields are:
<command>		shell command (via putpath())
<component>		archive component name (via putpath())
<mode>			octal permissions
<dmajor>, <dminor>	major and minor decimal device numbers
<uid>, <gid>		user and group names (via putpath())
<path>			path name (via putpath())

b <mode> <dmajor> <dminor> <uid> <gid> <path>
	block device
c <mode> <dmajor> <dminor> <uid> <gid> <path>
	character device
d <mode> <uid> <gid> <path>
	directory
f <component> <uid> <gid> <path>
	ordinary file (rest of the information is in the archive component)
l <path1> <path2>
	hard link -- <path2> is the link to be created.
s <path1> <path2>
	symbolic link -- <path2> is the link to be created.
r <path>
	file to be removed
x <command>
	command to be executed
X <path>
	file to be executed
