Overriding the default order of attribute values

You can override the default order of attribute values by changing the assignment operator(=) for any attribute in the configuration file.
Table 1. Assignment operators and attribute ordering
Assignment Operator Description
-= Prepend the following values before any values determined by the default search order.
:= Replace any values determined by the default search order with the following values.
+= Append the following values after any values determined by the default search order.
For example, assume that the XLC_USR_CONFIG environment variable is set to point to the custom user-defined configuration file at ~/userconfig2.
Custom user-defined configuration file ~/userconfig2 Default configuration file vac.cfg
xlc_prepend: use=xlc
            options-=<B1>
xlc_replace: use=xlc
            options:=<B2>
xlc_append: use=xlc
            options+=<B3>

DEFLT: use=DEFLT
      options=<D>
xlc: use=DEFLT
    options=<B>  

DEFLT:
    options=<C>
The stanzas in the preceding configuration files use the following option sets, in the following orders:
  1. stanza xlc uses B, D, and C
  2. stanza xlc_prepend uses B1, B, D, and C
  3. stanza xlc_replace uses B2
  4. stanza xlc_append uses B, D, C, and B3

You can also use assignment operators to specify an attribute more than once. For example:

Figure 1. Using additional assignment operations
xlc: 
    use=xlc
    options-=-Isome_include_path
    options+=some options