The combination of nsswitch.conf file status message and action option determines what the routine does at each step. The combination of status and action make up the search criteria.
You can change default search criteria by explicitly specifying some other criteria by using the STATUS=action syntax shown above. For example, the default action for a NOTFOUND condition is to continue the search to the next source. For example, to specify for networks, the search should stop in a NOTFOUND condition, edit the networks line of the switch file. The line would read as follows.
networks: nis [NOTFOUND=return] files
The networks: nis [NOTFOUND=return] files line specifies a nondefault criterion for the NOTFOUND status. Nondefault criteria are delimited by square brackets.
In this example, the search routine behaves as follows:
If the networks map is available, and contains the needed information, the routine returns with a SUCCESS status message.
If the networks map is not available, the routine returns with an UNAVAIL status message. By default, the routine continues to search the appropriate /etc file.
If the networks map is available and found, but the map does not contain the needed information, the routine returns with a NOTFOUND message. But, instead of continuing on to search the appropriate /etc file, which would be the default behavior, the routine stops searching.
If the networks map is busy, the routine returns with an TRYAGAIN status message and by default continues on to search the appropriate /etc file.
Lookups in the nsswitch.conf file are done in the order in which items are listed. However, password updates are done in reverse order, unless otherwise specified by using the passwd -r repository command. See The Switch File and Password Information for more information.