.\" Copyright (C) Caldera International Inc. 2001-2002.  All rights reserved.
.\" 
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are
.\" met:
.\" 
.\" Redistributions of source code and documentation must retain the above
.\" copyright notice, this list of conditions and the following
.\" disclaimer.
.\" 
.\" Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 
.\" All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" 
.\" This product includes software developed or owned by Caldera
.\" International, Inc.  Neither the name of Caldera International, Inc.
.\" nor the names of other contributors may be used to endorse or promote
.\" products derived from this software without specific prior written
.\" permission.
.\" 
.\" USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA
.\" INTERNATIONAL, INC.  AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
.\" DISCLAIMED.  IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE LIABLE
.\" FOR ANY DIRECT, INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
.\" OR OTHERWISE) RISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
.\" IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\" 
.\" $FreeBSD: head/share/doc/psd/04.uprog/p1 96925 2002-05-19 06:13:52Z grog $
.\"
.\"	@(#)p1	8.1 (Berkeley) 6/8/93
.\"
.if n .ls 2
.if t .tr |\(or
.NH
INTRODUCTION
.PP
This paper describes how to write
programs 
that interface with the
.UC UNIX
operating system in a non-trivial way.
This includes programs that use files by name,
that use pipes,
that invoke other commands as they run,
or that attempt to catch interrupts and other signals
during execution.
.PP
The document collects material which is scattered
throughout several sections of
.I
The
.UC UNIX
Programmer's Manual
.R
[1]
for Version 7
.UC UNIX .
There is no attempt to be complete;
only generally useful material is dealt with.
It is assumed that you will be programming in C,
so you must be able to read the language
roughly up to the level of
.I
The C Programming Language
.R
[2].
Some of the material in sections 2 through 4
is based on
topics covered more carefully there.
You should also be familiar with
.UC UNIX
itself
at least
to the level of
.I
.UC UNIX
for Beginners
.R
[3].