Access to z/OS UNIX Files

Programs can access the information in UNIX files through z/OS UNIX System Services (z/OS UNIX) calls, such as open(pathname), read(file descriptor), and write(file descriptor). Programs can also access the information in UNIX files through the BSAM, BPAM, QSAM, and VSAM access methods. When you use BSAM or QSAM, a UNIX file is simulated as a single-volume sequential data set. When you use VSAM, a UNIX file is simulated as an ESDS. When you use BPAM, a UNIX directory and its files are simulated as a partitioned data set directory and its members.

You can use the following types of UNIX files with the access methods:

Regular files, including files accessed through Network File System (NFS), temporary file system (TFS), HFS, or z/OS File System (zFS)
Character special files
First-in-first-out (FIFO) special files
Symbolic links

Restriction: You cannot use the following types of UNIX files with the access methods:

UNIX directories, except indirectly through BPAM
External links

Files can reside on other systems. The access method user can use NFS to access them.