Intro(C)                      06 January 1993                       Intro(C)


 Name

    Intro - introduces UNIX commands

 Description

    This section describes the use of the individual commands available in
    the UNIX Operating System.  Each individual command is labeled with
    either a C, or a CP for easy reference from other volumes.  The letter
    ``C'' stands for ``command''.  The letter ``P'' stands for commands that
    come with the optional Development System (Programming).  For example,
    date(C) indicates a reference to a discussion of the date command in the
    C section; cc(CP) indicates a reference to a discussion of the cc command
    in the Development System.  The Development System is an optional supple-
    mental package to the standard Operating System.

    The ``ADM'' Administration section contains miscellaneous information
    including considerable system maintenance information.  Other reference
    sections include the ``M'' Miscellaneous section, the ``S'' System Ser-
    vices section, the ``HW'' Hardware section, and the ``F'' File Format
    section.

 Syntax

    Unless otherwise noted, commands described in the ``Syntax'' section of a
    manual page accept options and other arguments according to the following
    syntax and should be interpreted as explained below.

       name [-option...] [cmdarg...]

    where:

    [ ]          Surround an option or cmdarg that is not mandatory.

    ...          Indicates multiple occurrences of the option or cmdarg.

    name         The name of an executable file.

    option       This is always preceded by a ``-'' and may be in one of the
                 two following forms:

                 noargletter  A single letter representing an option without
                              an option-argument.  Note that more than one
                              noargletter option can be grouped after one
                              ``-'' (Rule 5 in the following text).

                 argletter    A single letter representing an option requir-
                              ing an option-argument.

    optarg       An option-argument (character string) satisfying a preceding
                 argletter.  Note that groups of optargs following an
                 argletter must be separated by commas or separated by white
                 space and quoted (Rule 8 below).

    cmdarg       Pathname (or other command argument) not beginning with
                 ``-'', or ``-'' by itself indicating the standard input.

    Command syntax standard: rules

    These command syntax rules are not followed by all current commands, but
    all new commands use them.  getopts(C) should be used by all shell pro-
    cedures to parse positional parameters and to check for legal options.
    It supports rules 3-10 below.  The enforcement of the other rules must be
    done by the command itself.

    1.   Command names (name above) must be between two and nine characters
         long.

    2.   Command names must include only lowercase letters and digits.

    3.   Option names (option above) must be one character long.

    4.   All options must be preceded by ``-''.

    5.   Options with no arguments may be grouped after a single ``-''.

    6.   The first option-argument (optarg above) following an option must be
         preceded by white space.

    7.   Option-arguments cannot be optional.

    8.   Groups of option-arguments following an option must either be
         separated by commas or separated by white space and quoted (for
         example, -o xxx,z,yy or -o "xxx z yy").

    9.   All options must precede operands (cmdarg above) on the command
         line.

    10.  ``--'' may be used to indicate the end of the options.

    11.  The order of the options relative to one another should not matter.

    12.  The relative order of the operands (cmdarg above) may affect their
         significance in ways determined by the command with which they
         appear.

    13.  ``-'' preceded and followed by white space should only be used to
         mean standard input.

 See also

    getopts(C), exit(S), getopt(S) and wait(S).

 Diagnostics

    Upon termination, each command returns 2 bytes of status, one supplied by
    the system and giving the cause for termination, and (in the case of
    ``normal'' termination) one supplied by the program (see wait(S) and
    exit(S)).  The former byte is 0 for normal termination; the latter is
    customarily 0 for successful execution and non-zero to indicate troubles
    such as erroneous parameters, bad or inaccessible data.  It is called
    variously ``exit code'', ``exit status'', or ``return code'', and is
    described only where special conventions are involved.

 Notes

    Not all commands adhere to the syntax described here.