HP-UX Reference (11i v1 00/12) - 1 User Commands N-Z (vol 2)

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nis+(1) nis+(1)

Name Expansion

The NIS+ service only accepts fully qualiﬁed names. However, since such names may be unwieldy, the

NIS+ commands in section 1 employ a set of standard expansion rules that will attempt to fully qualify a

partially qualiﬁed name. This expansion is actually done by the NIS+ library function nis_getnames(3N)

which generates a list of names using the default NIS+ directory search path or the NIS_PATH environ-

ment variable. The default NIS+ directory search path includes all the names in its path.

nis_getnames() is invoked by the functions nis_lookup(3N) and nis_list(3N) when the EXPAND_NAME

ﬂag is used.

The NIS_PATH environment variable contains an ordered list of simple names. The names are separated

by the ‘:’ (colon) character. If any name in the list contains colons, the colon should be quoted as described

in the Grammar section. When the list is exhausted, the resolution function returns the error

NIS_NOTFOUND . This may mask the fact that the name existed but a server for it was unreachable. If

the name presented to the list or lookup interface is fully qualiﬁed, the EXPAND_NAME ﬂag is ignored.

In the list of names from the NIS_PATH environment variable, the ’$’ (dollar sign) character is treated

specially. Simple names that end with the label ’$’ have this character replaced by the default directory

(see nis_local_directory(3N)). Using "$" as a name in this list results in this name being replaced by the list

of directories between the default directory and the global root that contain at least two labels.

Below is an example of this expansion. Given the default directory of some.long.domain.name., and the

NIS_PATH variable set to fred.bar.:org_dir.$:$

. This path is initiallybroken up into the list:

fred.bar.

2 org_dir.$

3 $

The dollar sign in the second component is replaced by the default directory. The dollar sign in the third

component is replaced with the names of the directories between the default directory and the global root

that have at least two labels in them. The effective path value becomes:

1 fred.bar.

2a org_dir.some.long.domain.name.

3a some.long.domain.name.

3b long.domain.name.

3c domain.name.

Each of these simple names is appended to the partially qualiﬁed name that was passed to the

nis_lookup(3N) or nis_list(3N) interface. Each is tried in turn until NIS_SUCCESS is returned or the list

is exhausted.

If the NIS_PATH variable is not set, the path ‘‘$’’ is used.

The library function nis_getnames(3N) can be called from user programs to generate the list of names that

would be attempted. The program nisdefaults(1) with the -s option can also be used to show the fully

expanded path.

Concatenation Path

Normally all the entries for a certain type of information are stored within the table itself. However, there

are times when it is desirable for the table to point to other tables where entries can be found. For exam-

ple, you may want to store all the IP addresses in the host table for their own domain, and yet want to be

able to resolve hosts in some other domain without explicitly specifying the new domain name. NIS+ pro-

vides a mechanism for concatenating different but related tables with an "NIS+ Concatenation Path". With

a concatenation path, you can create a sort of ﬂat namespace from a hierarchical structure. You can also

create a table with no entries and just point the hosts or any other table to its parent domain. Note that

with such a setup, you are moving the administrative burden of managing the tables to the parent domain.

The concatenation path will slow down the request response time because more tables and more servers are

searched. It will also decrease the availability if all the servers are incapacitated for a particular directory

in the table path.

The NIS+ Concatenation Path is also referred to as the "table path". This path is set up at table creation

time through nistbladm(1). You can specify more than one table to be concatenated and they will be

searched in the given order. Note that the NIS+ client libraries, by default, will not follow the concatena-

HP-UX Release 11i: December 2000 − 3 − Section 1−−575

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