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Creating an external link z/OS UNIX System Services User's Guide SA23-2279-00 |
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An external link is a special type of symbolic link, a file that contains the name of an object outside of the z/OS UNIX file system. Using an external link, you associate that object with a path name. For example, setlocale() searches for locale object files in the z/OS UNIX file system, but if you want to keep your locale object files in a partitioned data set, you can create an external link in the file system that points to the PDS. This will improve performance by shortening the search made by setlocale(). A file can be an external link to a sequential data set, a PDS, or a PDS member. When a file is an external link to an MVS™ data set, an NFS client user can use the path name to access the data set. To use the path name to edit, browse, or display the attributes of the data set that is the target of an external link, you must be using the Network File System feature. Working in a shell, you can create (ln) an external link, display information (ls) about the link (not the target of the link), or delete (rm) the link. These services support external links:
Figure 1. External link:
A new file. An external link has an inode number. The MVS data set does not.
To create an external link to a data set, use this command format:
In Figure 1, /u/brooks/plib/pgm1 is the name
of the new file that contains the reference to the partitioned data
set BROOKS.PLIB.PGM1.Limitations of an external link: z/OS UNIX C programs running cannot fopen() or fread() an external link. For more information, see the ln command description in z/OS UNIX System Services Command Reference. Due to NFS protocol limitations, -e does not create an external link on NFS. For more information on creating an external link on NFS, see Creating an external link in z/OS Network File System Guide and Reference. |
Copyright IBM Corporation 1990, 2014
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