# Appendix B. Reference Information

#### Contents:

Invocation Options
Built-in Commands and Keywords
Predefined Aliases
Built-in Shell Variables
Test Operators
Options
Typeset Options
Arithmetic
Emacs Mode Commands
vi Control Mode Commands
Using getopts

This appendix contains reference lists for invocation options, built-in commands and keywords, predefined aliases, built-in shell variables, test operators, shell options, typeset options, arithmetic, emacs-mode commands, and vi-mode control commands. Furthermore, it describes how to use the full facilities of the built-in getopts command.

## B.1. Invocation Options

Here is a list of the options you can use when invoking the Korn shell. In addition to these, any set option can be used on the command line; see the table on options later in this appendix. Login shells are usually invoked with the options -i (interactive), -s (read from standard input), and -m (enable job control).

Option | Meaning
--- | ---
`-c` `string` | Execute string, then exit.
`-D` | Print all `$"`...`"` strings in the script. This is for use in creating a database of locale-specific translations of strings in a script.
`-i` | Interactive shell. Ignore signals TERM, INTR, and QUIT.
`-r` | Restricted shell. See Chapter 10.
`-R` `filename` | Create a cross-reference database for variable and command definitions in filename. May not be compiled in.
`-s` | Read commands from the standard input. If an argument is given, this flag takes precedence (i.e., the argument won't be treated as a script name and standard input will be read).

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