intro.1

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)intro.1	8.1	9/11/90
.\" SCCSID: @(#)intro.1	8.1	9/11/90
.TH intro 1
.SH Name
intro \- introduction to commands
.SH Description
.NXR "intro(1) keyword"
This section describes publicly accessible commands in alphabetic order.
Certain distinctions of purpose are made in the headings:
.TP 10
(1)
Commands of general utility.
.TP
(1c)
Commands for communication with other systems.
.TP
(1g)
Commands used primarily for graphics and computer-aided design.
.TP
(1int)
Commands used for internationalization.  For more information
see 
.MS internat 1int .
.TP
(1mh)
Commands specific to the Message Handler.
.TP
(1ncs)
Commands used for NCS (Network Computing System).
.TP
(1sh5)
Commands interpreted by the sh5 (System V Release 2) shell.
.TP
(1yp)
Commands specific to the Yellow Pages (YP) service.
.PP
.NT Note
Commands related to system maintenance used to appear in
section 1 reference pages and were distinguished by (1m) at the top of the
page.  These reference pages now appear in section 8.
.SH Diagnostics
.NXR "diagnostics" "explained"
Upon termination each command returns two bytes of status,
one supplied by the system giving the cause for
termination and, in the case of normal termination,
one supplied by the program.  For more information, see
.MS wait 1
and 
.MS exit 2 .
The former byte is 0 for normal termination; the latter
is customarily 0 for successful execution.  
A nonzero status indicates a problem such as erroneous parameters,
or bad or inaccessible data.
It is called variously exit code, exit status, or
return code, and is described only where
special conventions are involved.
.NXR "exit status" "defined"
.NXR "return code" "exit status"
.NXR "exit code" "exit status"