STREAMS Programming Guide

System Calls Used

Table 4-1 summarizes the system calls commonly used in controlling and transferring data and messages within a stream.

Table 4–1 System Calls Used

System Call 

Description 

read(2)

Reads data from a stream  

write(2)

Writes data to a stream  

ioctl(2)

Controls a stream  

getmsg(2)

Receives a message at the stream head  

getpmsg(2)

Receives a priority message at the stream head  

putmsg(2)

Sends a message downstream  

putpmsg(2)

Sends a priority message downstream  

poll(2)

Identifies files on which a user can send or receive messages, or on which certain events have occurred (historically, it was unnecessarily restricted to streams) 

pipe(2)

Creates a bidirectional channel that provides a communication path between multiple processes