4.4BSD Edition .AU M. Kirk McKusick, Michael Karels .AU Samuel Leffler, William Joy .AU Robert Fabry .AI Computer Systems Research Group Computer Science Division Department of Electrical Engineering and Computer Science University of California, Berkeley Berkeley, CA 94720 .EH 'PSD:5-%''4.4BSD Architecture Manual' .OH '4.4BSD Architecture Manual''PSD:5-%' .AB This document summarizes the system calls provided by the 4.4BSD operating system. It does not attempt to act as a tutorial for use of the system, nor does it attempt to explain or justify the design of the system facilities. It gives neither motivation nor implementation details, in favor of brevity.

The first section describes the basic kernel functions provided to a process: process naming and protection, memory management, software interrupts, time and statistics functions, object references (descriptors), and resource controls. These facilities, as well as facilities for bootstrap, shutdown and process accounting, are provided solely by the kernel.

The second section describes the standard system abstractions for files and filesystems, communication, terminal handling, and process control and debugging. These facilities are implemented by the operating system or by network server processes. .AE

.bp +3 .sy echo -n >toc .sy echo >>toc '.L\\$1 "\\$2" \\n%' \\$2 .\} \\$2

.\} .. \\$1\\$2 .. \\$1\\$2 .. .sy echo >>toc '.Nm \\$1 \\$2 "\\$3' .. .Sh 0 "Notation and Types

The notation used to describe system calls is a variant of a C language function call, consisting of a prototype call followed by the declaration of parameters and results. An additional keyword result, not part of the normal C language, is used to indicate which of the declared entities receive results. As an example, consider the read call, as described in section .Xr 2.1.1 : cc = read(fd, buf, nbytes); result ssize_t cc; int fd; result void *buf; size_t nbytes; The first line shows how the read routine is called, with three parameters. As shown on the second line, the return value cc is a size_t and read also returns information in the parameter buf.

The descriptions of error conditions arising from each system call are not provided here; they appear in section .Xr 2 of the Programmer's Reference Manual. In particular, when accessed from the C language, many calls return a characteristic -1 value when an error occurs, returning the error code in the global variable errno. Other languages may present errors in different ways.

A number of system standard types are defined by the include file <sys/types.h> and used in the specifications here and in many C programs.