The I/O activity of a process is primarily determined by various I/O statements that the process executes. These include statements for reading from, writing to, opening, and closing files. For an overview of I/O features available in programming languages, refer to the I/O Subsystem Programming Guide.

There are also a number of task attributes that affect various global aspects of process I/O activity. For example, you can use task attributes to establish default locations for files used by a process or to specify defaults for handling printer output produced by a process. This section introduces the functions of task attributes that affect process I/O activity and some related system commands.