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Network Administration

Search Logic

Under the OS/390 and CMS operating systems, the data set that contains configuration information usually has a name that is derived from the equivalent UNIX filename. For example, the OS/390 data set name ETC.HOSTS is derived from the UNIX filename /etc/hosts .

The socket library uses the following search logic when searching for the data set containing configuration information:

  1. It determines the name by using an environment variable if one has been set. The name should begin with a SAS/C prefix, such as DSN: for a data set name, or HFS: for a hierarchical file system (HFS) name. If the name does not begin with a prefix, it is interpreted according to the SAS/C Library defaults, which vary from program to program. For example, the default prefix for OS/390 is DDN:, and for CMS it is CMS:. Use the DSN: prefix if you are supplying the name in DSName form.

  2. Under TSO, it searches for a data set name that is composed of the user's userid (TSO: prefix) and the name derived from the UNIX filename.

  3. It searches for a data set name derived solely from a UNIX filename. Under OS/390, the library does not perform this step if the TCPIP_PREFIX environment variable is not TCPIP. See Specifying TCPIP_PREFIX for OS/390 for a discussion of TCPIP_PREFIX .

  4. Under OS/390, it searches for a data set derived from a UNIX filename and prefixed by the TCPIP_PREFIX value.

Finding the Data Set

The socket library uses the following methods to look for each of the configuration data sets:

/etc/protocols

The socket library looks for the following data set names while searching for the OS/390 or CMS data set that is equivalent to /etc/protocols :

  1. value of ETC_PROTOCOLS environment variable, if defined

  2. //hfs:/etc/protocols OS/390 (integrated sockets only)

  3. tso-prefix.ETC.PROTO under TSO

  4. ETC.PROTO under OS/390, or ETC PROTO under CMS

  5. tcpip-prefix.ETC.PROTO under OS/390, if TCPIP_PREFIX is not blank.


/etc/services

The socket library looks for the following data set names while searching for the OS/390 or CMS data set that is equivalent to /etc/services :

  1. value of ETC_SERVICES environment variable, if defined

  2. //hfs:/etc/services OS/390 (integrated sockets only)

  3. tso-prefix.ETC.SERVICES under TSO

  4. ETC.SERVICES under OS/390, or ETC SERVICES under CMS

  5. tcpip-prefix.ETC.SERVICES under OS/390, if TCPIP_PREFIX is not blank.


/etc/hosts

The socket library looks for the following data set names while searching for the OS/390 or CMS data set that is equivalent to /etc/hosts :

  1. value of ETC_HOSTS environment variable, if defined

  2. //hfs:/etc/hosts OS/390 (integrated sockets only)

  3. tso-prefix.ETC.HOSTS under TSO

  4. ETC.HOSTS under OS/390, or ETC HOSTS under CMS

  5. tcpip-prefix.ETC.HOSTS under OS/390, if TCPIP_PREFIX is not blank.


/etc/networks

The socket library looks for the following data set names while searching for the OS/390 or CMS data set that is equivalent to /etc/networks :

  1. value of ETC_NETWORKS environment variable, if defined

  2. //hfs:/etc/networks OS/390 (integrated sockets only)

  3. tso-prefix.ETC.NETWORKS under TSO

  4. ETC.NETWORKS under OS/390, or ETC NETWORKS under CMS

  5. tcpip-prefix.ETC.NETWORKS under OS/390, if TCPIP_PREFIX is not blank.


/etc/resolv.conf

The socket library looks for the following data set names while searching for the OS/390 or CMS data set that is equivalent to /etc/resolv.conf :

  1. value of ETC_RESOLV_CONF environment variable, if defined

  2. //hfs:/etc/resolv.conf OS/390 (integrated sockets only)

  3. tso-prefix.ETC.RESOLV.CONF under TSO

  4. ETC.RESOLV.CONF under OS/390, or ETC RESOLV under CMS

  5. tcpip-prefix.ETC.RESOLV.CONF under OS/390, if TCPIP_PREFIX is not blank.


/etc/rpc

The socket library looks for the following data set names while searching for the OS/390 or CMS data set that is equivalent to /etc/rpc :

  1. value of ETC_RPC environment variable, if defined.

  2. //hfs:/etc/rpc OS/390 (integrated sockets only)

  3. tso-prefix.ETC.RPC under TSO. Under OS/390 but not under TSO, it looks for tcpip-prefix.ETC.RPC if a userid can be determined for the address space.

  4. ETC.RPC under OS/390, or ETC RPC under CMS.

  5. tcpip-prefix.ETC.RPC under OS/390, if TCPIP_PREFIX is not blank.

When the socket library finds a data set with one of the above names, the name is retained for the duration of the program's execution. You may need to restart the program for the socket library to find a different filename.


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