getopt - Unix, Linux Command

getopt [options] [--] optstring parameters 

getopt [options] -o|--options optstring [options] [--] parameters 

The parameters
getopt is called with can be divided into two parts: options
which modify the way getopt will parse
(options and
-o|--options optstring in the
SYNOPSIS), and the parameters which are to be
parsed
(parameters in the
SYNOPSIS). The second part will start at the first non-option parameter
that is not an option argument, or after the first occurrence of
‘--’. If no
‘-o’ or
‘--options’ option is found in the first part, the first
parameter of the second part is used as the short options string.


If the environment variable
GETOPT_COMPATIBLE is set, or if its first parameter
is not an option (does not start with a
‘-’, this is the first format in the
SYNOPSIS), getopt will generate output that is compatible with that of other versions of
getopt(1).
It will still do parameter shuffling and recognize optional
arguments (see section
COMPATIBILITY for more information).


Traditional implementations of
getopt(1)
are unable to cope with whitespace and other (shell-specific) special characters
in arguments and non-option parameters. To solve this problem, this
implementation can generate
quoted output which must once again be interpreted by the shell (usually
by using the
eval command). This has the effect of preserving those characters, but
you must call
getopt in a way that is no longer compatible with other versions (the second
or third format in the
SYNOPSIS). To determine whether this enhanced version of
getopt(1)
is installed, a special test option
(-T) can be used.


The parameters are parsed from left to right. Each parameter is classified as a
short option, a long option, an argument to an option,
or a non-option parameter.


A simple short option is a
‘-’ followed by a short option character. If
the option has a required argument, it may be written directly after the option
character or as the next parameter (ie. separated by whitespace on the
command line). If the
option has an optional argument, it must be written directly after the
option character if present.


It is possible to specify several short options after one
‘-’, as long as all (except possibly the last) do not have required or optional
arguments.


A long option normally begins with
‘--’ followed by the long option name.
If the option has a required argument, it may be written directly after
the long option name, separated by
‘=’, or as the next argument (ie. separated by whitespace on the command line).
If the option has an optional argument, it must
be written directly after the long option name, separated by
‘=’, if present (if you add the
‘=’ but nothing behind it, it is interpreted
as if no argument was present; this is a slight bug, see the
BUGS). Long options may be abbreviated, as long as the abbreviation is not
ambiguous.


Each parameter not starting with a
‘-’, and not a required argument of
a previous option, is a non-option parameter. Each parameter after
a
‘--’ parameter is always interpreted as a non-option parameter.
If the environment variable
POSIXLY_CORRECT is set, or if the short
option string started with a
‘+’, all remaining parameters are interpreted
as non-option parameters as soon as the first non-option parameter is
found.


If there are problems parsing the parameters, for example because a
required argument is not found or an option is not recognized, an error
will be reported on stderr, there will be no output for the offending
element, and a non-zero error status is returned.


For a short option, a single
‘-’ and the option character are generated
as one parameter. If the option has an argument, the next
parameter will be the argument. If the option takes an optional argument,
but none was found, the next parameter will be generated but be empty in
quoting mode,
but no second parameter will be generated in unquoted (compatible) mode.
Note that many other
getopt(1)
implemetations do not support optional arguments.


If several short options were specified after a single
‘-’, each will be present in the output as a separate parameter.


For a long option,
‘--’ and the full option name are generated as one
parameter. This is done regardless whether the option was abbreviated or
specified with a single
‘-’ in the input. Arguments are handled as with short options.


Normally, no non-option parameters output is generated until all options
and their arguments have been generated. Then
‘--’ is generated as a
single parameter, and after it the non-option parameters in the order
they were found, each as a separate parameter.
Only if the first character of the short options string was a
‘-’, non-option parameter output is generated at the place they are found in the
input (this is not supported if the first format of the
SYNOPSIS is used; in that case all preceding occurrences of
‘-’ and
‘+’ are ignored).


Quoting is not enabled if the environment variable
GETOPT_COMPATIBLE is set, if the first form of the
SYNOPSIS is used, or if the option
‘-u’ is found.


Different shells use different quoting conventions. You can use the
‘-s’ option to select the shell you are using. The following shells are
currently supported:
‘sh’, ‘bash’, ‘csh’ and
‘tcsh’. Actually, only two ‘flavors’ are distinguished: sh-like quoting conventions
and csh-like quoting conventions. Chances are that if you use another shell
script language, one of these flavors can still be used.




If the first character is
‘+’, or if the environment variable
POSIXLY_CORRECT is set, parsing stops as soon as the first non-option parameter
(ie. a parameter that does not start with a
‘-’) is found that
is not an option argument. The remaining parameters are all interpreted as
non-option parameters.


If the first character is a
‘-’, non-option parameters are outputed at the place where they are found; in normal
operation, they are all collected at the end of output after a
‘--’ parameter has been generated. Note that this
‘--’ parameter is still generated, but it will always be the last parameter in
this mode.


If the first character of the first parameter of getopt is not a
‘-’, getopt goes into compatibility mode. It will interpret its first parameter as
the string of short options, and all other arguments will be parsed. It
will still do parameter shuffling (ie. all non-option parameters are outputed
at the end), unless the environment variable
POSIXLY_CORRECT is set.


The environment variable
GETOPT_COMPATIBLE forces
getopt into compatibility mode. Setting both this environment variable and
POSIXLY_CORRECT offers 100% compatibility for ‘difficult’ programs. Usually, though,
neither is needed.


In compatibility mode, leading
‘-’ and
‘+’ characters in the short options string are ignored.

#!/bin/bash

# read the options
TEMP=`getopt -o f:s::d:a:: --long file-name:,source::,destination:,action:: -- "$@"`
eval set -- "$TEMP"

# extract options and their arguments into variables.
while true ; do
    case "$1" in
        -f|--file-name)
            fileName=$2 ; shift 2 ;;
        -s|--source)
            case "$2" in
                "") sourceDir='.' ; shift 2 ;;
                 *) sourceDir=$2 ; shift 2 ;;
            esac ;;
        -d|--destination)
            destinationDir=$2 ; shift 2;;
        -a|--action)
            case "$2" in
                "copy"|"move") action=$2 ; shift 2 ;;
                            *) action="copy" ; shift 2 ;;
            esac ;;
        --) shift ; break ;;
        *) echo "Internal error!" ; exit 1 ;;
    esac
done

# Now take action
echo "$action file $fileName from $sourceDir to $destinationDir"

-f or --file-name: Parameter is mandatory (indicated by :)
-s or --source: Parameter is options (indicated by ::), default current directory
-d or --destination: Parameter is mandatory
-a or --action (Copy): Parameter is options default is copy

$ ./getopt.sh -f MyFile.txt -s/home -d /home/test -aMove
Move file MyFile.txt from /home to /home/test

$ ./getopt.sh --file-name MyFile.txt --source=/home --dest /home/test --act=Move
Move file MyFile.txt from /home to /home/test

$ ./getopt.sh --file-name MyFile.txt --source=/home --dest /home/test --act
Copy file MyFile.txt from /home to /home/test

$ ./getopt.sh --file-name MyFile.txt --source=/home -a Move -d
getopt: option requires an argument -- d
Copy file MyFile.txt from /home to


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