test

<B>Digital的Unix操作系统VAX 4.2源码</B>

.PP
This is a test of the refer program.
Because the bibliography supplied by Bell Labs
contains nothing but programming references, 
that will be the subject here.
.PP
For serious programmers, there are several
indispensable reference works.
The book describing the C programming language
is an excellent starting place for those
who already know another language such as Pascal or Fortran.
.[
kernighan ritchie prentice-hall
%P 34-39
.]
It is rich with examples of programs that work,
probably the most valuable resource a programming book can provide.
.PP
When learning the Unix system,
it will be necessary to have a reference guide
such as the Programmer's Manual.
Section 1 is useful for everyone,
but only programmers need sections 2 through 8.
.[
thompson ritchie seventh
%O The version 6 manual is outdated by now.
.]
Be sure to get the Version 7 edition,
if you have a Version 7 installation.
.PP
One of the strong suits of the Unix system is the ability
to build parsers and compilers for new languages.
Several tools are provided to this end,
most notably \fIlex\fP and \fIyacc\fP.
For an introduction to the theory involved,
see the book by Aho and Ullman on LALR parsing.
.[
aho ullman addison-wesley
.]
Several of the most unusual Unix software tools,
such as \fIeqn\fP, \fIawk\fP, and \fBbc\fP,
were developed with the aid of \fIyacc\fP.
Of course, the reference of last resort is
.[
thompson ritchie seventh
.]
as mentioned above.