getopt/trunk/getopt.1

.TH GETOPT "1" "June 2012" "Linux" "User Commands"
.SH NAME
getopt \- parse command options (enhanced)
.SH SYNOPSIS
.BI getopt
.I optstring parameters
.br
.B getopt
.RI [ options ]
.RB [ \-\- ]
.I optstring parameters
.br
.B getopt
.RI [ options ]
.BR \-o | \-\-options
.I optstring
.RI [ options ]
.RB [ \-\- ]
.I parameters
.SH DESCRIPTION
.B getopt
is used to break up
.RI ( parse )
options in command lines for easy parsing by shell procedures, and to
check for legal options.  It uses the
.SM GNU
.BR getopt (3)
routines to do this.
.PP
The parameters
.B getopt
is called with can be divided into two parts: options which modify
the way
.B getopt
will do the parsing
.RI "(the " options
and the
.I optstring
in the
.BR SYNOPSIS ),
and the parameters which are to be parsed
.RI ( parameters
in the
.BR SYNOPSIS ).
The second part will start at the first non\-option parameter that is
not an option argument, or after the first occurrence of
.RB ' \-\- '.
If no
.RB ' \-o '
or
.RB ' \-\-options '
option is found in the first part, the first parameter of the second
part is used as the short options string.
.PP
If the environment variable
.B GETOPT_COMPATIBLE
is set, or if the first \fIparameter\fR is not an option (does not start
with a
.RB ' \- ',
the first format in the
.BR SYNOPSIS ),
.B getopt
will generate output that is compatible with that of other versions of
.BR getopt (1).
It will still do parameter shuffling and recognize optional arguments
(see section
.B COMPATIBILITY
for more information).
.PP
Traditional implementations of
.BR 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
.B eval
command).  This has the effect of preserving those characters, but
you must call
.B getopt
in a way that is no longer compatible with other versions (the second
or third format in the
.BR SYNOPSIS ).
To determine whether this enhanced version of
.BR getopt (1)
is installed, a special test option
.RB ( \-T )
can be used.
.SH OPTIONS
.TP
.BR \-a , " \-\-alternative"
Allow long options to start with a single
.RB ' \- '.
.TP
.BR \-h , " \-\-help"
Display help text and exit.  No other output is generated.
.TP
.BR \-l , " \-\-longoptions \fIlongopts\fP"
The long (multi\-character) options to be recognized.  More than one
option name may be specified at once, by separating the names with
commas.  This option may be given more than once, the
.I longopts
are cumulative.  Each long option name in
.I longopts
may be followed by one colon to indicate it has a required argument,
and by two colons to indicate it has an optional argument.
.TP
.BR \-n , " \-\-name \fIprogname\fP"
The name that will be used by the
.BR getopt (3)
routines when it reports errors.  Note that errors of
.BR getopt (1)
are still reported as coming from getopt.
.TP
.BR \-o , " \-\-options \fIshortopts\fP"
The short (one\-character) options to be recognized.  If this option
is not found, the first parameter of
.B getopt
that does not start with a
.RB ' \- '
(and is not an option argument) is used as the short options string.
Each short option character in
.I shortopts
may be followed by one colon to indicate it has a required argument,
and by two colons to indicate it has an optional argument.  The first
character of shortopts may be
.RB ' + '
or
.RB ' \- '
to influence the way options are parsed and output is generated (see
section
.B SCANNING MODES
for details).
.TP
.BR \-q , " \-\-quiet"
Disable error reporting by getopt(3).
.TP
.BR  \-Q , " \-\-quiet\-output"
Do not generate normal output.  Errors are still reported by
.BR getopt (3),
unless you also use
.BR \-q .
.TP
.BR \-s , " \-\-shell \fIshell\fP"
Set quoting conventions to those of \fIshell\fR.
If the \fB\-s\fR option is not given, the
.SM BASH
conventions are used.  Valid arguments are currently
.RB ' sh '
.RB ' bash ',
.RB ' csh ',
and
.RB ' tcsh '.
.TP
.BR \-u , " \-\-unquoted"
Do not quote the output.  Note that whitespace and special
(shell\-dependent) characters can cause havoc in this mode (like they
do with other
.BR getopt (1)
implementations).
.TP
.BR \-T , " \-\-test"
Test if your
.BR getopt (1)
is this enhanced version or an old version.  This generates no
output, and sets the error status to 4.  Other implementations of
.BR getopt (1),
and this version if the environment variable
.B GETOPT_COMPATIBLE
is set, will return
.RB ' \-\- '
and error status 0.
.TP
.BR \-V , " \-\-version"
Display version information and exit.  No other output is generated.
.SH PARSING
This section specifies the format of the second part of the
parameters of
.B getopt
(the
.I parameters
in the
.BR SYNOPSIS ).
The next section
.RB ( OUTPUT )
describes the output that is generated.  These parameters were
typically the parameters a shell function was called with.  Care must
be taken that each parameter the shell function was called with
corresponds to exactly one parameter in the parameter list of
.B getopt
(see the
.BR EXAMPLES ).
All parsing is done by the GNU
.BR getopt (3)
routines.
.PP
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.
.PP
A simple short option is a
.RB ' \- '
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 (i.e. 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.
.PP
It is possible to specify several short options after one
.RB ' \- ',
as long as all (except possibly the last) do not have required or
optional arguments.
.PP
A long option normally begins with
.RB ' \-\- '
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
.RB ' = ',
or as the next argument (i.e. 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
.RB ' = ',
if present (if you add the
.RB ' = '
but nothing behind it, it is interpreted as if no argument was
present; this is a slight bug, see the
.BR BUGS ).
Long options may be abbreviated, as long as the abbreviation is not
ambiguous.
.PP
Each parameter not starting with a
.RB ' \- ',
and not a required argument of a previous option, is a non\-option
parameter.  Each parameter after a
.RB ' \-\- '
parameter is always interpreted as a non\-option parameter.  If the
environment variable
.B POSIXLY_CORRECT
is set, or if the short option string started with a
.RB ' + ',
all remaining parameters are interpreted as non\-option parameters as
soon as the first non\-option parameter is found.
.SH OUTPUT
Output is generated for each element described in the previous
section.  Output is done in the same order as the elements are
specified in the input, except for non\-option parameters.  Output
can be done in
.I compatible
.RI ( unquoted )
mode, or in such way that whitespace and other special characters
within arguments and non\-option parameters are preserved (see
.BR QUOTING ).
When the output is processed in the shell script, it will seem to be
composed of distinct elements that can be processed one by one (by
using the shift command in most shell languages).  This is imperfect
in unquoted mode, as elements can be split at unexpected places if
they contain whitespace or special characters.
.PP
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.
.PP
For a short option, a single
.RB ' \- '
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
.BR getopt (1)
implementations do not support optional arguments.
.PP
If several short options were specified after a single
.RB ' \- ',
each will be present in the output as a separate parameter.
.PP
For a long option,
.RB ' \-\- '
and the full option name are generated as one parameter.  This is
done regardless whether the option was abbreviated or specified with
a single
.RB ' \- '
in the input.  Arguments are handled as with short options.
.PP
Normally, no non\-option parameters output is generated until all
options and their arguments have been generated.  Then
.RB ' \-\- '
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
.RB ' \- ',
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
.B SYNOPSIS
is used; in that case all preceding occurrences of
.RB ' \- '
and
.RB ' + '
are ignored).
.SH QUOTING
In compatible mode, whitespace or 'special' characters in arguments
or non\-option parameters are not handled correctly.  As the output
is fed to the shell script, the script does not know how it is
supposed to break the output into separate parameters.  To circumvent
this problem, this implementation offers quoting.  The idea is that
output is generated with quotes around each parameter.  When this
output is once again fed to the shell (usually by a shell
.B eval
command), it is split correctly into separate parameters.
.PP
Quoting is not enabled if the environment variable
.B GETOPT_COMPATIBLE
is set, if the first form of the
.B SYNOPSIS
is used, or if the option
.RB ' \-u '
is found.
.PP
Different shells use different quoting conventions.  You can use the
.RB ' \-s '
option to select the shell you are using.  The following shells are
currently supported:
.RB ' sh ',
.RB ' bash ',
.RB ' csh '
and
.RB ' 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.
.SH "SCANNING MODES"
The first character of the short options string may be a
.RB ' \- '
or a
.RB ' + '
to indicate a special scanning mode.  If the first calling form in
the
.B SYNOPSIS
is used they are ignored; the environment variable
.B POSIXLY_CORRECT
is still examined, though.
.PP
If the first character is
.RB ' + ',
or if the environment variable
.B POSIXLY_CORRECT
is set, parsing stops as soon as the first non\-option parameter
(i.e. a parameter that does not start with a
.RB ' \- ')
is found that is not an option argument.  The remaining parameters
are all interpreted as non\-option parameters.
.PP
If the first character is a
.RB ' \- ',
non\-option parameters are outputted at the place where they are
found; in normal operation, they are all collected at the end of
output after a
.RB ' \-\- '
parameter has been generated.  Note that this
.RB ' \-\- '
parameter is still generated, but it will always be the last
parameter in this mode.
.SH COMPATIBILITY
This version of
.BR getopt (1)
is written to be as compatible as possible to other versions.
Usually you can just replace them with this version without any
modifications, and with some advantages.
.PP
If the first character of the first parameter of getopt is not a
.RB ' \- ',
.B 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 (i.e. all
non\-option parameters are output at the end), unless the
environment variable
.B POSIXLY_CORRECT
is set.
.PP
The environment variable
.B GETOPT_COMPATIBLE
forces
.B getopt
into compatibility mode.  Setting both this environment variable and
.B POSIXLY_CORRECT
offers 100% compatibility for 'difficult' programs.  Usually, though,
neither is needed.
.PP
In compatibility mode, leading
.RB ' \- '
and
.RB ' + '
characters in the short options string are ignored.
.SH RETURN CODES
.B getopt
returns error code
.B 0
for successful parsing,
.B 1
if
.BR getopt (3)
returns errors,
.B 2
if it does not understand its own parameters,
.B 3
if an internal error occurs like out\-of\-memory, and
.B 4
if it is called with
.BR \-T .
.SH EXAMPLES
Example scripts for (ba)sh and (t)csh are provided with the
.BR getopt (1)
distribution, and are optionally installed in
.BR /usr/local/share/getopt/
or
.BR /usr/share/getopt/ .
.SH ENVIRONMENT
.IP POSIXLY_CORRECT
This environment variable is examined by the
.BR getopt (3)
routines.  If it is set, parsing stops as soon as a parameter is
found that is not an option or an option argument.  All remaining
parameters are also interpreted as non\-option parameters, regardless
whether they start with a
.RB ' \- '.
.IP GETOPT_COMPATIBLE
Forces
.B getopt
to use the first calling format as specified in the
.BR SYNOPSIS .
.SH BUGS
.BR getopt (3)
can parse long options with optional arguments that are given an
empty optional argument (but can not do this for short options).
This
.BR getopt (1)
treats optional arguments that are empty as if they were not present.
.PP
The syntax if you do not want any short option variables at all is
not very intuitive (you have to set them explicitly to the empty
string).
.SH AUTHOR
.MT frodo@frodo.looijaard.name
Frodo Looijaard
.ME
.SH "SEE ALSO"
.BR getopt (3),
.BR bash (1),
.BR tcsh (1).
.SH AVAILABILITY
You can download the latest getopt from
.UR http://frodo.looijaard.name/project/getopt
the author's home page
.UE .
It is also part of the util-linux package which is available from
.UR ftp://\:ftp.kernel.org\:/pub\:/linux\:/utils\:/util-linux/
Linux Kernel Archive
.UE .
1	frodo	365	.TH GETOPT "1" "June 2012" "Linux" "User Commands"
2	frodo	259	.SH NAME
3			getopt \- parse command options (enhanced)
4			.SH SYNOPSIS
5	frodo	365	.BI getopt
6	frodo	324	.I optstring parameters
7			.br
8			.B getopt
9			.RI [ options ]
10			.RB [ \-\- ]
11			.I optstring parameters
12			.br
13			.B getopt
14			.RI [ options ]
15			.BR \-o \| \-\-options
16			.I optstring
17			.RI [ options ]
18			.RB [ \-\- ]
19			.I parameters
20	frodo	259	.SH DESCRIPTION
21			.B getopt
22	frodo	324	is used to break up
23	frodo	259	.RI ( parse )
24	frodo	365	options in command lines for easy parsing by shell procedures, and to
25			check for legal options. It uses the
26	frodo	259	.SM GNU
27	frodo	324	.BR getopt (3)
28	frodo	259	routines to do this.
29	frodo	365	.PP
30	frodo	324	The parameters
31	frodo	259	.B getopt
32	frodo	365	is called with can be divided into two parts: options which modify
33			the way
34			.B getopt
35			will do the parsing
36			.RI "(the " options
37			and the
38	frodo	324	.I optstring
39			in the
40			.BR SYNOPSIS ),
41	frodo	365	and the parameters which are to be parsed
42	frodo	259	.RI ( parameters
43	frodo	324	in the
44			.BR SYNOPSIS ).
45	frodo	365	The second part will start at the first non\-option parameter that is
46			not an option argument, or after the first occurrence of
47			.RB ' \-\- '.
48	frodo	324	If no
49	frodo	365	.RB ' \-o '
50	frodo	324	or
51	frodo	365	.RB ' \-\-options '
52			option is found in the first part, the first parameter of the second
53			part is used as the short options string.
54			.PP
55	frodo	259	If the environment variable
56			.B GETOPT_COMPATIBLE
57	frodo	365	is set, or if the first \fIparameter\fR is not an option (does not start
58			with a
59			.RB ' \- ',
60			the first format in the
61	frodo	324	.BR SYNOPSIS ),
62	frodo	259	.B getopt
63	frodo	324	will generate output that is compatible with that of other versions of
64			.BR getopt (1).
65	frodo	365	It will still do parameter shuffling and recognize optional arguments
66			(see section
67	frodo	259	.B COMPATIBILITY
68	frodo	324	for more information).
69	frodo	365	.PP
70	frodo	259	Traditional implementations of
71			.BR getopt (1)
72	frodo	365	are unable to cope with whitespace and other (shell\-specific)
73			special characters in arguments and non\-option parameters. To solve
74			this problem, this implementation can generate quoted output which
75			must once again be interpreted by the shell (usually by using the
76	frodo	259	.B eval
77	frodo	365	command). This has the effect of preserving those characters, but
78	frodo	324	you must call
79	frodo	259	.B getopt
80	frodo	324	in a way that is no longer compatible with other versions (the second
81			or third format in the
82			.BR SYNOPSIS ).
83	frodo	259	To determine whether this enhanced version of
84			.BR getopt (1)
85			is installed, a special test option
86	frodo	324	.RB ( \-T )
87	frodo	259	can be used.
88			.SH OPTIONS
89	frodo	324	.TP
90			.BR \-a , " \-\-alternative"
91			Allow long options to start with a single
92	frodo	365	.RB ' \- '.
93	frodo	324	.TP
94			.BR \-h , " \-\-help"
95	frodo	365	Display help text and exit. No other output is generated.
96	frodo	324	.TP
97			.BR \-l , " \-\-longoptions \fIlongopts\fP"
98	frodo	365	The long (multi\-character) options to be recognized. More than one
99			option name may be specified at once, by separating the names with
100			commas. This option may be given more than once, the
101	frodo	324	.I longopts
102	frodo	365	are cumulative. Each long option name in
103	frodo	324	.I longopts
104	frodo	365	may be followed by one colon to indicate it has a required argument,
105			and by two colons to indicate it has an optional argument.
106	frodo	324	.TP
107			.BR \-n , " \-\-name \fIprogname\fP"
108			The name that will be used by the
109	frodo	259	.BR getopt (3)
110	frodo	365	routines when it reports errors. Note that errors of
111	frodo	259	.BR getopt (1)
112			are still reported as coming from getopt.
113	frodo	324	.TP
114			.BR \-o , " \-\-options \fIshortopts\fP"
115	frodo	365	The short (one\-character) options to be recognized. If this option
116			is not found, the first parameter of
117	frodo	324	.B getopt
118	frodo	365	that does not start with a
119			.RB ' \- '
120	frodo	259	(and is not an option argument) is used as the short options string.
121	frodo	365	Each short option character in
122	frodo	324	.I shortopts
123	frodo	259	may be followed by one colon to indicate it has a required argument,
124	frodo	365	and by two colons to indicate it has an optional argument. The first
125			character of shortopts may be
126			.RB ' + '
127	frodo	259	or
128	frodo	365	.RB ' \- '
129			to influence the way options are parsed and output is generated (see
130			section
131	frodo	259	.B SCANNING MODES
132			for details).
133	frodo	324	.TP
134			.BR \-q , " \-\-quiet"
135	frodo	259	Disable error reporting by getopt(3).
136	frodo	324	.TP
137			.BR \-Q , " \-\-quiet\-output"
138	frodo	365	Do not generate normal output. Errors are still reported by
139	frodo	324	.BR getopt (3),
140			unless you also use
141	frodo	365	.BR \-q .
142	frodo	324	.TP
143			.BR \-s , " \-\-shell \fIshell\fP"
144	frodo	365	Set quoting conventions to those of \fIshell\fR.
145			If the \fB\-s\fR option is not given, the
146	frodo	259	.SM BASH
147	frodo	365	conventions are used. Valid arguments are currently
148			.RB ' sh '
149			.RB ' bash ',
150			.RB ' csh ',
151	frodo	259	and
152	frodo	365	.RB ' tcsh '.
153	frodo	324	.TP
154			.BR \-u , " \-\-unquoted"
155	frodo	365	Do not quote the output. Note that whitespace and special
156			(shell\-dependent) characters can cause havoc in this mode (like they
157			do with other
158	frodo	259	.BR getopt (1)
159			implementations).
160	frodo	324	.TP
161			.BR \-T , " \-\-test"
162			Test if your
163			.BR getopt (1)
164	frodo	365	is this enhanced version or an old version. This generates no
165			output, and sets the error status to 4. Other implementations of
166	frodo	259	.BR getopt (1),
167			and this version if the environment variable
168			.B GETOPT_COMPATIBLE
169	frodo	365	is set, will return
170			.RB ' \-\- '
171	frodo	259	and error status 0.
172	frodo	324	.TP
173			.BR \-V , " \-\-version"
174	frodo	365	Display version information and exit. No other output is generated.
175	frodo	259	.SH PARSING
176	frodo	365	This section specifies the format of the second part of the
177			parameters of
178	frodo	259	.B getopt
179	frodo	324	(the
180			.I parameters
181			in the
182			.BR SYNOPSIS ).
183			The next section
184			.RB ( OUTPUT )
185	frodo	365	describes the output that is generated. These parameters were
186			typically the parameters a shell function was called with. Care must
187			be taken that each parameter the shell function was called with
188			corresponds to exactly one parameter in the parameter list of
189	frodo	324	.B getopt
190			(see the
191			.BR EXAMPLES ).
192			All parsing is done by the GNU
193			.BR getopt (3)
194			routines.
195	frodo	365	.PP
196			The parameters are parsed from left to right. Each parameter is
197			classified as a short option, a long option, an argument to an
198			option, or a non\-option parameter.
199			.PP
200	frodo	324	A simple short option is a
201	frodo	365	.RB ' \- '
202			followed by a short option character. If the option has a required
203			argument, it may be written directly after the option character or as
204			the next parameter (i.e. separated by whitespace on the command
205			line). If the option has an optional argument, it must be written
206			directly after the option character if present.
207			.PP
208	frodo	324	It is possible to specify several short options after one
209	frodo	365	.RB ' \- ',
210			as long as all (except possibly the last) do not have required or
211			optional arguments.
212			.PP
213	frodo	324	A long option normally begins with
214	frodo	365	.RB ' \-\- '
215			followed by the long option name. If the option has a required
216			argument, it may be written directly after the long option name,
217			separated by
218			.RB ' = ',
219			or as the next argument (i.e. separated by whitespace on the command
220			line). If the option has an optional argument, it must be written
221			directly after the long option name, separated by
222			.RB ' = ',
223	frodo	324	if present (if you add the
224	frodo	365	.RB ' = '
225			but nothing behind it, it is interpreted as if no argument was
226			present; this is a slight bug, see the
227	frodo	259	.BR BUGS ).
228			Long options may be abbreviated, as long as the abbreviation is not
229			ambiguous.
230	frodo	365	.PP
231	frodo	324	Each parameter not starting with a
232	frodo	365	.RB ' \- ',
233			and not a required argument of a previous option, is a non\-option
234			parameter. Each parameter after a
235			.RB ' \-\- '
236			parameter is always interpreted as a non\-option parameter. If the
237			environment variable
238	frodo	324	.B POSIXLY_CORRECT
239	frodo	365	is set, or if the short option string started with a
240			.RB ' + ',
241			all remaining parameters are interpreted as non\-option parameters as
242			soon as the first non\-option parameter is found.
243	frodo	259	.SH OUTPUT
244	frodo	365	Output is generated for each element described in the previous
245			section. Output is done in the same order as the elements are
246			specified in the input, except for non\-option parameters. Output
247			can be done in
248	frodo	324	.I compatible
249	frodo	259	.RI ( unquoted )
250	frodo	365	mode, or in such way that whitespace and other special characters
251			within arguments and non\-option parameters are preserved (see
252	frodo	259	.BR QUOTING ).
253			When the output is processed in the shell script, it will seem to be
254	frodo	365	composed of distinct elements that can be processed one by one (by
255			using the shift command in most shell languages). This is imperfect
256			in unquoted mode, as elements can be split at unexpected places if
257			they contain whitespace or special characters.
258			.PP
259	frodo	259	If there are problems parsing the parameters, for example because a
260	frodo	365	required argument is not found or an option is not recognized, an
261			error will be reported on stderr, there will be no output for the
262			offending element, and a non\-zero error status is returned.
263			.PP
264	frodo	324	For a short option, a single
265	frodo	365	.RB ' \- '
266			and the option character are generated as one parameter. If the
267			option has an argument, the next parameter will be the argument. If
268			the option takes an optional argument, but none was found, the next
269			parameter will be generated but be empty in quoting mode, but no
270			second parameter will be generated in unquoted (compatible) mode.
271	frodo	324	Note that many other
272			.BR getopt (1)
273			implementations do not support optional arguments.
274	frodo	365	.PP
275	frodo	324	If several short options were specified after a single
276	frodo	365	.RB ' \- ',
277	frodo	259	each will be present in the output as a separate parameter.
278	frodo	365	.PP
279	frodo	324	For a long option,
280	frodo	365	.RB ' \-\- '
281			and the full option name are generated as one parameter. This is
282			done regardless whether the option was abbreviated or specified with
283			a single
284			.RB ' \- '
285			in the input. Arguments are handled as with short options.
286			.PP
287			Normally, no non\-option parameters output is generated until all
288			options and their arguments have been generated. Then
289			.RB ' \-\- '
290			is generated as a single parameter, and after it the non\-option
291			parameters in the order they were found, each as a separate
292			parameter. Only if the first character of the short options string
293			was a
294			.RB ' \- ',
295			non\-option parameter output is generated at the place they are found
296			in the input (this is not supported if the first format of the
297	frodo	259	.B SYNOPSIS
298	frodo	262	is used; in that case all preceding occurrences of
299	frodo	365	.RB ' \- '
300	frodo	324	and
301	frodo	365	.RB ' + '
302	frodo	324	are ignored).
303	frodo	259	.SH QUOTING
304	frodo	365	In compatible mode, whitespace or 'special' characters in arguments
305			or non\-option parameters are not handled correctly. As the output
306			is fed to the shell script, the script does not know how it is
307			supposed to break the output into separate parameters. To circumvent
308			this problem, this implementation offers quoting. The idea is that
309			output is generated with quotes around each parameter. When this
310			output is once again fed to the shell (usually by a shell
311	frodo	324	.B eval
312	frodo	259	command), it is split correctly into separate parameters.
313	frodo	365	.PP
314	frodo	259	Quoting is not enabled if the environment variable
315			.B GETOPT_COMPATIBLE
316			is set, if the first form of the
317			.B SYNOPSIS
318			is used, or if the option
319	frodo	365	.RB ' \-u '
320	frodo	259	is found.
321	frodo	365	.PP
322			Different shells use different quoting conventions. You can use the
323			.RB ' \-s '
324			option to select the shell you are using. The following shells are
325	frodo	259	currently supported:
326	frodo	365	.RB ' sh ',
327			.RB ' bash ',
328			.RB ' csh '
329	frodo	259	and
330	frodo	365	.RB ' tcsh '.
331			Actually, only two 'flavors' are distinguished: sh\-like quoting
332			conventions and csh\-like quoting conventions. Chances are that if
333			you use another shell script language, one of these flavors can still
334			be used.
335	frodo	259	.SH "SCANNING MODES"
336			The first character of the short options string may be a
337	frodo	365	.RB ' \- '
338	frodo	259	or a
339	frodo	365	.RB ' + '
340			to indicate a special scanning mode. If the first calling form in
341			the
342	frodo	324	.B SYNOPSIS
343	frodo	259	is used they are ignored; the environment variable
344			.B POSIXLY_CORRECT
345			is still examined, though.
346	frodo	365	.PP
347	frodo	324	If the first character is
348	frodo	365	.RB ' + ',
349	frodo	324	or if the environment variable
350	frodo	259	.B POSIXLY_CORRECT
351	frodo	324	is set, parsing stops as soon as the first non\-option parameter
352	frodo	365	(i.e. a parameter that does not start with a
353			.RB ' \- ')
354			is found that is not an option argument. The remaining parameters
355			are all interpreted as non\-option parameters.
356			.PP
357	frodo	259	If the first character is a
358	frodo	365	.RB ' \- ',
359			non\-option parameters are outputted at the place where they are
360			found; in normal operation, they are all collected at the end of
361			output after a
362			.RB ' \-\- '
363			parameter has been generated. Note that this
364			.RB ' \-\- '
365			parameter is still generated, but it will always be the last
366			parameter in this mode.
367	frodo	259	.SH COMPATIBILITY
368	frodo	324	This version of
369	frodo	259	.BR getopt (1)
370	frodo	365	is written to be as compatible as possible to other versions.
371			Usually you can just replace them with this version without any
372			modifications, and with some advantages.
373			.PP
374	frodo	324	If the first character of the first parameter of getopt is not a
375	frodo	365	.RB ' \- ',
376			.B getopt
377			goes into compatibility mode. It will interpret its first
378			parameter as the string of short options, and all other arguments
379			will be parsed. It will still do parameter shuffling (i.e. all
380			non\-option parameters are output at the end), unless the
381			environment variable
382	frodo	324	.B POSIXLY_CORRECT
383	frodo	259	is set.
384	frodo	365	.PP
385	frodo	324	The environment variable
386			.B GETOPT_COMPATIBLE
387			forces
388	frodo	259	.B getopt
389	frodo	365	into compatibility mode. Setting both this environment variable and
390	frodo	259	.B POSIXLY_CORRECT
391	frodo	365	offers 100% compatibility for 'difficult' programs. Usually, though,
392	frodo	259	neither is needed.
393	frodo	365	.PP
394	frodo	324	In compatibility mode, leading
395	frodo	365	.RB ' \- '
396	frodo	324	and
397	frodo	365	.RB ' + '
398	frodo	259	characters in the short options string are ignored.
399			.SH RETURN CODES
400			.B getopt
401	frodo	324	returns error code
402			.B 0
403			for successful parsing,
404	frodo	259	.B 1
405			if
406			.BR getopt (3)
407			returns errors,
408	frodo	324	.B 2
409	frodo	259	if it does not understand its own parameters,
410			.B 3
411			if an internal error occurs like out\-of\-memory, and
412			.B 4
413	frodo	324	if it is called with
414	frodo	259	.BR \-T .
415			.SH EXAMPLES
416			Example scripts for (ba)sh and (t)csh are provided with the
417			.BR getopt (1)
418	frodo	324	distribution, and are optionally installed in
419	frodo	365	.BR /usr/local/share/getopt/
420	frodo	324	or
421	frodo	365	.BR /usr/share/getopt/ .
422	frodo	259	.SH ENVIRONMENT
423			.IP POSIXLY_CORRECT
424			This environment variable is examined by the
425			.BR getopt (3)
426	frodo	365	routines. If it is set, parsing stops as soon as a parameter is
427			found that is not an option or an option argument. All remaining
428	frodo	259	parameters are also interpreted as non\-option parameters, regardless
429	frodo	324	whether they start with a
430	frodo	365	.RB ' \- '.
431	frodo	259	.IP GETOPT_COMPATIBLE
432			Forces
433			.B getopt
434			to use the first calling format as specified in the
435			.BR SYNOPSIS .
436			.SH BUGS
437			.BR getopt (3)
438	frodo	365	can parse long options with optional arguments that are given an
439			empty optional argument (but can not do this for short options).
440			This
441	frodo	259	.BR getopt (1)
442			treats optional arguments that are empty as if they were not present.
443	frodo	365	.PP
444	frodo	259	The syntax if you do not want any short option variables at all is
445	frodo	324	not very intuitive (you have to set them explicitly to the empty
446	frodo	259	string).
447			.SH AUTHOR
448	frodo	365	.MT frodo@frodo.looijaard.name
449			Frodo Looijaard
450			.ME
451	frodo	259	.SH "SEE ALSO"
452			.BR getopt (3),
453			.BR bash (1),
454			.BR tcsh (1).
455	frodo	365	.SH AVAILABILITY
456			You can download the latest getopt from
457			.UR http://frodo.looijaard.name/project/getopt
458			the author's home page
459			.UE .
460			It is also part of the util-linux package which is available from
461			.UR ftp://\:ftp.kernel.org\:/pub\:/linux\:/utils\:/util-linux/
462			Linux Kernel Archive
463			.UE .
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