Creating, modifying, and deleting objects and attributes

You can create, modify, and delete objects and attributes, as shown in the following table:

If you want to: Do this:
Create a new object Create a file with the name of the object. The new object will come into existence with no attributes. You can then write attributes to the object, as required.
Delete an object Delete the object file.
Create a new attribute Write the attribute to the object file.
Modify an attribute Write the new attribute value to the object file. Note that there's no need to lseek() to the attribute's position in the file first; seeking has no meaning in PPS.
Delete all existing attributes Open the object with O_TRUNC.
Delete one attribute Prefix its name with a minus sign, then call write(). For example: 
// Delete the "url" attribute
sprintf( ppsobj, "-url\n" ); 
write( ppsobj-fd, ppsobj, strlen( ppsobj ) );
CAUTION:
Note the following about deleting attributes:
  • Calling ftruncate() on an object file deletes all the object's attributes, whatever the value of the length argument.
  • A simple Bourne shell redirection instruction (such as echo attr::hello > /pps/object) entered from the command line opens an object with O_TRUNC and deletes all attributes.
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