intro(1) DG/UX 5.4.2 intro(1)
NAME
intro - introduction to commands and application programs
DESCRIPTION
This section describes, in alphabetical order, publicly-accessible
commands.
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 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
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intro(1) DG/UX 5.4.2 intro(1)
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.
DIAGNOSTICS
Upon termination, each command returns two 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(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.
SEE ALSO
getopts(1), exit(2), wait(2), getopt(3C).
NOTES
Many commands do not adhere to the aforementioned syntax.
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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