intro(1)
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intro Command
introduction to commands and application programs
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DESCRIPTION
This section describes, in alphabetical order, publicly-
accessible commands. Certain distinctions of purpose are made in
the headings:
(1) Commands of general utility.
(1C) Commands for communication with other systems.
COMMAND SYNTAX
Unless otherwise noted, commands described in this section accept
options and other arguments according to the following syntax:
name [option(s)] [cmdarg(s)]
name The name of an executable file.
option - noargletter(s) or,
- argletter<>optarg
where <> is optional white space.
noargletter A single letter representing an option without an
argument.
argletter A single letter representing an option requiring an
argument.
optarg Argument (character string) satisfying preceding
argletter.
cmdarg Path name (or other command argument) not beginning
with - or, - by itself indicating the standard
input.
Command Syntax Standard: Rules
All new commands will follow the syntax rules below. Because
existing commands have been developed at various times by various
people, some commands will not follow the rules below.
Getopts(1) should be used by all shell procedures to parse
positional parameters and to check for legal options. Getopts(1)
supports Rules 3-10 below. The command itself must enforce the
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other rules.
1. Command names (name above) must be between two and nine
characters long.
2. Command names must include only lower-case 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 (e.g., -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(1).
exit(2), wait(2), getopt(3C) in the Programmer's Reference for
the DG/UX System
DIAGNOSTICS
Upon termination, each command returns two bytes of status, one
supplied by the system and giving the cause for termination, and
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(in the case of normal termination) one supplied by the program
(see wait(2) and exit(2)). 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, or other inability to cope with the
task at hand. It is called variously "exit code," "exit status,"
or "return code," and is described only where special conventions
are involved.
BUGS
Many commands do not adhere to the aforementioned syntax.
WARNINGS
Some commands produce unexpected results when processing files
containing null characters. These commands often treat text
input lines as strings and therefore become confused upon
encountering a null character (the string terminator) within a
line.
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