GETOPTS

Section: Misc. Reference Manual Pages (3) Updated: libbash getopts Library Manual Local index Up

BSD mandoc

NAME

getopts - libbash library for command line parameters parsing

SYNOPSIS

Ft $retval getopt_long Aq Instructions Aq Parameters

DESCRIPTION

This is a documentation for libbash getopts library, that implements getopt_long function for bash(1). For documentation of bash getopts function, please see getopts(1) ( getopts(1posix) on some systems).

Here is a table for reference:

getopts(1): (or 1posix on some systems) implemented by bash
getopts(3): implemented by libbash
getopt(1): implemented by getopt utils (part of util-linux)
getopt_long1: implemented by libbash and installed to section 1 instead of 3 to prevent collision with C man pages.
getopt(3): implemented by GNU C library.
getopt_long3: implemented by GNU C library.

I have also seen separate getopt utility which part of util-linux package.

The getopt_long function parses the command line arguments. It uses Fa Instructions as the rules for parsing the Fa Parameters .

The Instructions

A string that specifies rules for parameters parsing. The instructions string is built of a group of independent instructions, separated by a white space. Each instruction must have the following structure:

-<SingleLetter>|--<MultiLetter>-><VariableName>[:]

This structure contains three parts:

-<SingleLetter>

This is the parameter single-letter sign. For example -h

--<MultiLetter>

This is the parameter's corresponding multi-letter sign. For example --help

<VariableName>[:]

This is the name of the variable that will contain the parameter value. For example: HELP

The Variable name can represent one of two variables types:

Flag variable (not followed by `:': In this case, it will hold the value 1 if `on' (i.e. was specified on command line) and will not be defined if `off'
Value variable (followed by `:': ) In this case, the value it will hold is the string that was given as the next parameter in the Fa Parameters string (Separated by white-space or `=' ). If input contains more then one instance of the considered command line option, an array of the given parameters will be set as the value of the variable.

The Parameters

The Fa Parameters are simply the parameters you wish to parse.

RETURN VALUE

This function returns a string that contains a set of variables definitions. In order to define the variables, this string should be given as a parameter to eval function. This value is returned in the variable Fa $retval .

EXAMPLES

Parse command line parameters looking for the flags -h | --help and -v | --version and for the value -p | --path :

getopt_long '-h|--help->HELP 
              -v|--version->VERSION 
              -p|--path->PATH:' $*
eval $retval

In this example, for the parameters --help --path=/usr/ the variables that will be created are:

HELP=1
PATH=/usr/

for the parameters --help --path=/usr --path=/bin the variables that will be created are:

HELP=1
PATH=(/usr /bin)

BUGS

Values must not contain the string `__getopts__'. This string will be parsed as a single white-space.

A value should not start with an already defined multi-letter sign. If such a value exists, it will be treated as the equivalent singe-letter sign. This bug only accures when using a single-letter sign, or a multi-letter sign that are not followed by a `='.

For example: If we have a script named `foo', and we parse the parameters `-d|--dir:' and `-f|--file:', then