Gengetopt is a tool to write command line option parsing code for C programs.
This is Edition 2.18 of the Gengetopt manual.
It documents GNU Gengetopt version 2.18.
This manual is for GNU Gengetopt (version 2.18, 4 September 2006), a tool to write command line option parsers for C programs.
Copyright © 2001 - 2006 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, with the Front-Cover Texts being “A GNU Manual,” and with the Back-Cover Texts as in (a) below. A copy of the license is included in the section entitled “GNU Free Documentation License.”(a) The FSF's Back-Cover Text is: “You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development.”
Gengetopt is a tool to generate C code to parse the command line
arguments argc and argv that are part of every C or C++
program. The generated code uses the C library function
getopt_long to perform the actual command line parsing.
This manual is written for C and C++ programmers, specifically the lazy ones. If you've written any non-trivial C program, you've had to deal with argument parsing. It isn't particularly difficult, nor is it particularly exciting. It is one of the classic programming nuisances, which is why most books on programming leave it as an exercise for the reader. Gengetopt can save you from this work, leaving you free to focus on the interesting parts of your program.
Thus your program will be able to handle command line options such as:
myprog --input foo.c -o foo.o --no-tabs -i 100 *.class
And both long options (those that start with --) and short
options (start with - and consist of only one character) can be
handled (see Terminology for further details). For standards about
short and long options you may want to take a look at the GNU Coding
Standards (http://www.gnu.org/prep/standards_toc.html).
Gengetopt can also generate a function to save the command line options into a file (see Basic Usage), and a function to read the command line options from a file (see Configuration files). Of course, these two kinds of files are compliant.
Gengetopt is free software; you are free to use, share and modify it under the terms of the GNU General Public License that accompanies this manual.
The code that Gengetopt generates is also free software; however it is licensed with a simple all-permissive license instead of the GPL or LGPL. You are free to do anything you like with the generated code, including incorporating it into or linking it with proprietary software.
Gengetopt was originally written by Roberto Arturo Tena Sanchez. It is currently maintained by Lorenzo Bettini http://www.lorenzobettini.it.
A primordial version of Terminology was written by Adam Greenblatt.
See the file INSTALL for detailed building and installation instructions; anyway if you're used to compiling Linux software that comes with sources you may simply follow the usual procedure, i.e. untar the file you downloaded in a directory and then:
cd <source code main directory>
./configure
make
make install
Note: unless you specify a different install directory by
--prefix option of
configure (e.g. ./configure --prefix=<your home>),
you must be root to run make install.
Files will be installed in the following directories:
executables/prefix/bin
docs/prefix/share/doc/gengetopt
examples/prefix/share/doc/gengetopt/examples
additional files/prefix/share/gengetopt
Default value for prefix is /usr/local
but you may change it with --prefix
option to configure.
You can download it from GNU's ftp site: ftp://ftp.gnu.org/gnu/gengetopt or from one of its mirrors (see http://www.gnu.org/prep/ftp.html).
I do not distribute Windows binaries anymore; since, they can be easily built by using Cygnus C/C++ compiler, available at http://www.cygwin.com. However, if you don't feel like downloading such compiler, you can request such binaries directly to me, by e-mail (find my e-mail at my home page) and I can send them to you.
Archives are digitally signed by me (Lorenzo Bettini) with GNU gpg (http://www.gnupg.org). My GPG public key can be found at my home page (http://www.lorenzobettini.it).
You can also get the patches, if they are available for a particular release (see below for patching from a previous version).
This project's CVS repository can be checked out through anonymous (pserver) CVS with the following instruction:
cvs -z3 -d:pserver:anonymous@cvs.savannah.gnu.org:/sources/gengetopt co gengetopt
Further instructions can be found at the address:
http://savannah.gnu.org/projects/gengetopt.
Please notice that this way you will get the latest development sources of Gengetopt, which may also be unstable. This solution is the best if you intend to correct/extend this program: you should send me patches against the latest cvs repository sources.
If, on the contrary, you want to get the sources of a given release,
through cvs, say, e.g., version X.Y.Z, you must specify the tag
rel_X_Y_Z when you run the cvs command or the cvs update
command.
When you compile the sources that you get through the cvs repository,
before running the configure and make commands, you
should, at least the first time, run the command:
sh reconf
This will run the autotools commands in the correct order, and also copy
possibly missing files. You should have installed recent versions of
automake and autoconf in order for this to succeed.
You will also need flex and bison.
NOTICE: This convention holds since release 2.14.
Gengetopt has been developed under GNU/Linux, using gcc (C++), and bison (yacc) and flex (lex), and ported under Win32 with Cygnus C/C++compiler, available at http://www.cygwin.com. I used the excellent GNU Autoconf and GNU Automake. I also used Autotools (ftp://ftp.ugcs.caltech.edu/pub/elef/autotools) which creates a starting source tree (according to GNU standards) with autoconf, automake starting files.
Moreover Gengen (http://www.lorenzobettini.it/software/gengen) is used for automatically generating the code that generates the command line parser.
Actually, you don't need all these tools above to build gengetopt because I provide generated sources, unless you want to develop gengetopt.
The code generated by gengetopt relies on the getopt_long
function that is usually in the standard C library; however, there may
be some implementations of the C library that don't include it; in this
case you have to link the program that uses the file generated by
gengetopt with the files getopt.c and getopt1.c and
include gnugetopt.h in your project. We obviously provide these
files in the utility files directory (<install
prefix>/share/gengetopt). These files are part of the GNU C library.
You may want to take a look at getopt_long man page.
Read also No getopt_long, for instructions on how to check whether getopt_long is part of the library and how to deal with their lacking (using autoconf and automake).
If you downloaded a patch, say gengetopt-1.3-1.3.1-patch.gz (i.e., the patch to go from version 1.3 to version 1.3.1), cd to the directory with sources from the previous version (gengetopt-1.3) and type:
gunzip -cd ../gengetopt-1.3-1.3.1.patch.gz | patch -p1
and restart the compilation process (if you had already run configure a simple make should do).
The command line options, which have to be handled by gengetopt generated function, are specified in a file (typically with .ggo extension). This file consist in lines of sentences with the following formats, commands in {} are optional1:
package <packname>
version <version>
args <command line options>
option <long> <short> <desc> \
{argtype} {typestr="<type descr>"} \
{values="<value1>","<value2>",...} \
{default="<default value>"} \
{dependon="<other option>"} \
{required} {argoptional} {multiple} \
{hidden}
option <long> <short> <desc> flag <on/off>
section "section name" {sectiondesc="optional section description"}
text "a textual sentence"
Where:
packagePACKAGE generated by autoconf.
versionVERSION generated by autoconf.
purposeargsargs2 you can specify options
that will be added to the command line options of gengetopt itself. For
instance, if you always run gengetopt on your input file with the
options --no-handle-error --string-parser -u, you can add these
options in the input file like this:
args "--no-handle-error --string-parser -u"
and remove those recurrent options from the command line.
long-) and a dot (.). No spaces
allowed. The name of the variables generated to store arguments (see
later in this section) are long options converted to be legal C variable
names. This means that . and - are both replaced by
_.
short- is specified, then no short option is considered for the long
option (thus long options with no associated short options are allowed).
desc-) and a dot (.). The first character must not be
a space. This description will be printed during the output of
--help. Wrapping will be automatically performed, and \n
is interpreted as a newline request.
argtypestring, int, short, long, float,
double, longdouble or longlong. If no type is
specified the option does not accept an argument.
typestr--help (e.g., "filename" instead
of simply STRING, or "portnumber" instead of simply
INT).
valuesdefaultdependonrequiredrequired or optional. This specifies whether such option
must be given at each program invocation. These keywords were
introduced in release 2.17. Before, you had to use the keywords
yes or no. You can still use these keywords but their use
is not advised since they are not much explicative.
argoptional= in case you use a long option, and avoid spaces if
you use short option. For instance, if the option with optional
argument is -B|--bar, use the following command line syntax:
-B15 or --bar=15, and NOT the following one -B 15
nor --bar 15.
By using this specification together with default you can obtain
an option that even if not explicitly specified will have the default
value, and if it is specified without an argument it will have, again,
the default value.
multiplerequired flag. See Multiple Options.
hidden--help but it can still be specified at
command line3. In case hidden options
are used, the command line option --full-help will also be
generated. This will print also the hidden options4.
on/offon or off. This is the state of the flag when the program
starts. If user specifies the option, the flag toggles.
The part that must be provided in the correct order is
option <long> <short> <desc>
while the other specifications can be given in any order5. Thus, for instance
option <long> <short> <desc> {argtype} {typestr="<type descr>"}
is the same as
option <long> <short> <desc> {typestr="<type descr>"} {argtype}
Comments begins with # in any place of the line and ends in the
end of line.
Notice that the options -h,--help and -V,--version are
added automatically; however, if you specify an option yourself that has
h as short form or help as long form, then
-h,--help is not added (and you have to handle the help option
manually). The same holds for -V,--version.
In case hidden options are used, See Hidden options, the
command line option --full-help will also be generated. This
will print also the hidden options6.
Options can be part of sections, that provide a more meaningful
descriptions of the options. A section can be defined with the
following syntax (the sectiondesc is optional) and all the options
following a section declaration are considered part of that sections:
section "section name" {sectiondesc="optional section description"}
Notice that the separation in sections is stronger than separation in
groups of mutual exclusive options (see Group options).
Furthermore, sections should not be inserted among group options (but
only externally). A section makes sense only if it is followed by some
options. If you don't specify any option after a section, that section
will not be printed at all. If you need to simply insert some text in
the output of --help, then you must use text, explained in
the next paragraph.
You can insert, among options, a textual string that will be printed in
the output of --help7:
text "\nA text description with possible line\nbreaks"
Of course, you can use this mechanism even to manually insert blank lines among options with an empty text string:
text ""
You can also specify the list of values that can be passed to an
option (in that case the option has type string). If a value
that is not in the list is passed, an error is raised. You can think of
such options as enumerated options. It is not necessary to pass
the complete value at the command line option: a non ambiguous prefix
will do. For instance, if the accepted values are
"foo","bar","foobar", then you can pass at the command line the
value "b" and the value "bar" will be selected, or the
value "foob" and the value "foobar" will be selected;
instead, passing the value "fo" will raise an ambiguity error.
Here's an example of such a file (the file is called sample1.ggo)
# file sample1.ggo
option "str-opt" s "A string option, for a filename" \
string typestr="filename" optional
text "\nA brief text description"
text " before the other options.\n"
option "my-opt" m "Another integer option, \
this time the description of the \
option should be quite long to require wrapping... possibly \
more than one wrapping :-) especially if I\nrequire a line break" \
int optional
option "int-opt" i "A int option" int required
section "more involved options" \
sectiondesc="the following options\nare more complex"
text ""
option "flag-opt" - "A flag option" flag off
option "funct-opt" F "A function option" optional
section "last option section"
option "long-opt" - "A long option" long optional
option "def-opt" - "A string option with default" \
string default="Hello" optional
option "enum-opt" - "A string option with list of values" \
values="foo","bar","hello","bye" default="hello" optional
option "secret" S "hidden option will not appear in --help" \
int optional hidden
option "dependant" D "option that depends on str-opt" \
int optional dependon="str-opt"
text "\nAn ending text."
The simplest way to use gengetopt is to pass this file as the standard input, i.e.:
gengetopt < sample1.ggo
By default gengetopt generates cmdline.h and cmdline.c. Otherwise we can specify these names with a command line option:
gengetopt < sample1.ggo --file-name=cmdline1 --unamed-opts
The option --unamed-opts allows the generated command line parser
to accept also names, without an option (for instance you can pass a
file name without an option in front of it, and also use wildcards, such
as *.c, foo*.? and so on). These are also called
parameters (see Terminology). You can specify an optional
description for these additional names (default is FILES).
In cmdline1.h you'll find the generated C struct:
/* cmdline1.h */
/* File autogenerated by gengetopt version 2.18rc */
#ifndef CMDLINE1_H
#define CMDLINE1_H
/* If we use autoconf. */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
#ifndef CMDLINE_PARSER_PACKAGE
#define CMDLINE_PARSER_PACKAGE "sample1"
#endif
#ifndef CMDLINE_PARSER_VERSION
#define CMDLINE_PARSER_VERSION "2.0"
#endif
struct gengetopt_args_info
{
const char *help_help; /* Print help and exit help description. */
const char *full_help_help; /* Print help, including hidden options, and exit help description. */
const char *version_help; /* Print version and exit help description. */
char * str_opt_arg; /* A string option, for a filename. */
char * str_opt_orig; /* A string option, for a filename original value given at command line. */
const char *str_opt_help; /* A string option, for a filename help description. */
int my_opt_arg; /* Another integer option, this time the description of the option should be quite long to require wrapping... possibly more than one wrapping :-) especially if I\nrequire a line break. */
char * my_opt_orig; /* Another integer option, this time the description of the option should be quite long to require wrapping... possibly more than one wrapping :-) especially if I\nrequire a line break original value given at command line. */
const char *my_opt_help; /* Another integer option, this time the description of the option should be quite long to require wrapping... possibly more than one wrapping :-) especially if I\nrequire a line break help description. */
int int_opt_arg; /* A int option. */
char * int_opt_orig; /* A int option original value given at command line. */
const char *int_opt_help; /* A int option help description. */
int flag_opt_flag; /* A flag option (default=off). */
const char *flag_opt_help; /* A flag option help description. */
const char *funct_opt_help; /* A function option help description. */
long long_opt_arg; /* A long option. */
char * long_opt_orig; /* A long option original value given at command line. */
const char *long_opt_help; /* A long option help description. */
char * def_opt_arg; /* A string option with default (default='Hello'). */
char * def_opt_orig; /* A string option with default original value given at command line. */
const char *def_opt_help; /* A string option with default help description. */
char * enum_opt_arg; /* A string option with list of values (default='hello'). */
char * enum_opt_orig; /* A string option with list of values original value given at command line. */
const char *enum_opt_help; /* A string option with list of values help description. */
int secret_arg; /* hidden option will not appear in --help. */
char * secret_orig; /* hidden option will not appear in --help original value given at command line. */
const char *secret_help; /* hidden option will not appear in --help help description. */
int dependant_arg; /* option that depends on str-opt. */
char * dependant_orig; /* option that depends on str-opt original value given at command line. */
const char *dependant_help; /* option that depends on str-opt help description. */
int help_given ; /* Whether help was given. */
int full_help_given ; /* Whether full-help was given. */
int version_given ; /* Whether version was given. */
int str_opt_given ; /* Whether str-opt was given. */
int my_opt_given ; /* Whether my-opt was given. */
int int_opt_given ; /* Whether int-opt was given. */
int flag_opt_given ; /* Whether flag-opt was given. */
int funct_opt_given ; /* Whether funct-opt was given. */
int long_opt_given ; /* Whether long-opt was given. */
int def_opt_given ; /* Whether def-opt was given. */
int enum_opt_given ; /* Whether enum-opt was given. */
int secret_given ; /* Whether secret was given. */
int dependant_given ; /* Whether dependant was given. */
char **inputs ; /* unamed options */
unsigned inputs_num ; /* unamed options number */
} ;
extern const char *gengetopt_args_info_purpose;
extern const char *gengetopt_args_info_usage;
extern const char *gengetopt_args_info_help[];
extern const char *gengetopt_args_info_full_help[];
int cmdline_parser (int argc, char * const *argv,
struct gengetopt_args_info *args_info);
int cmdline_parser2 (int argc, char * const *argv,
struct gengetopt_args_info *args_info,
int override, int initialize, int check_required);
int cmdline_parser_file_save(const char *filename,
struct gengetopt_args_info *args_info);
void cmdline_parser_print_help(void);
void cmdline_parser_print_full_help(void);
void cmdline_parser_print_version(void);
void cmdline_parser_init (struct gengetopt_args_info *args_info);
void cmdline_parser_free (struct gengetopt_args_info *args_info);
int cmdline_parser_required (struct gengetopt_args_info *args_info,
const char *prog_name);
extern char *cmdline_parser_enum_opt_values[] ; /* Possible values for enum-opt. */
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif /* CMDLINE1_H */
The <option>_given field is set to a value different from 0 when
an argument for <option> has been specified. If the option
accepts an argument and it is not of flag type The
<option>_arg field is set to the value passed at the command
line. The <option>_arg field has the corresponding C type
specified in the file passed to gengetopt. The additional field
<option>_orig is always a string containing the original value
passed at the command line. This may be different, for instance, in
case of numerical arguments: gengetopt converts the passed value (a
string) into the corresponding numerical type; due to convertions, float
representations, etc., this may not correspond exactly to the original
value passed at command line. It can also be different when enumerated
options are used (see above): in particular the <option>_arg
field will contain a value taken from the specified list, while
<option>_orig contains the (non-ambiguous) prefix specified at
the command line.
The user can always access this original value by using
<option>_orig instead of <option>_arg, as he sees
fit8. For instance, gengetopt itselfs uses the original value when it
saves the command line options into a file (see the _file_save
function in the following). However, apart from very specific command
line processing, the user might hardly need the <option>_orig
field, and can be always safely use <option>_arg.
The <option>_help contains the string (concerning this very
option) that is printed when --help command line is given.
If it is of flag type, only the field <option>_flag
is generated.
The strings cmdline_parser_purpose and
cmdline_parser_usage contain the purpose as specified in
the input file and the generated “usage” string as printed when
--help command line is given. Finally, the string array
cmdline_parser_help contains the strings (one for each option)
printed when --help command line is given (this array is
terminated by a null string element). If hidden options are used also
the cmdline_parser_full_help array is available (containing also
help strings concerning hidden options). All these strings can be used
by the programmer to build a customized help output9.
Even if <option>_given is 0, the corresponding
<option>_arg is set to default value (if one has been specified
for <option>). However, in this case, the <option>_orig
is set to NULL.
Notice that by default the generated function is called
cmdline_parser (see the command line options below, to override
this name), and it takes the arguments that main receives and a
pointer to such a struct, that it will be filled. Another version,
cmdline_parser2, can be specified more arguments. Since you
typically need this second version only in conjunction with other
“kinds” of parsers such as configuration files and multiple parsers,
you can find more details about it in Configuration files.
IMPORTANT: The array passed to the parser function (that in turn
is passed to getopt_long is expected to have in the first
element (of index 0) the name of the program that was invoked. This
will be used, for instance, for printing possible errors.
cmdline_parser_free can be called to deallocate memory
allocated by the parser for string and multiple options.
cmdline_parser_init can be called to initialize the struct (it is
not mandatory, since it is done automatically by the command line
parser).
cmdline_parser_file_save10 can be used to save the command line options into a
file. The contents of this file are consistent with the configuration
files (Configuration files). Notice that if an option has a
default value, this option will be saved into the file only if it was
passed explicitly at command line (or read from a configuration file),
i.e., default values will not be saved into the file.
And here's how these functions can be used inside the main program:
/* main1.cc */
/* we try to use gengetopt generated file in a C++ program */
/* we don't use autoconf and automake vars */
#include <iostream>
#include "stdlib.h"
#include "cmdline1.h"
using std::cout;
using std::endl;
int
main (int argc, char **argv)
{
gengetopt_args_info args_info;
cout << "This one is from a C++ program" << endl ;
cout << "Try to launch me with some options" << endl ;
cout << "(type sample1 --help for the complete list)" << endl ;
cout << "For example: ./sample1 *.* --funct-opt" << endl ;
/* let's call our cmdline parser */
if (cmdline_parser (argc, argv, &args_info) != 0)
exit(1) ;
cout << "Here are the options you passed..." << endl;
for ( unsigned i = 0 ; i < args_info.inputs_num ; ++i )
cout << "file: " << args_info.inputs[i] << endl ;
if ( args_info.funct_opt_given )
cout << "You chose --funct-opt or -F." << endl ;
if ( args_info.str_opt_given )
cout << "You inserted " << args_info.str_opt_arg << " for " <<
"--str-opt option." << endl ;
if ( args_info.int_opt_given )
cout << "This is the integer you input: " <<
args_info.int_opt_arg << "." << endl;
if (args_info.flag_opt_given)
cout << "The flag option was given!" << endl;
cout << "The flag is " << ( args_info.flag_opt_flag ? "on" : "off" ) <<
"." << endl ;
if (args_info.enum_opt_given) {
cout << "enum-opt value: " << args_info.enum_opt_arg << endl;
cout << "enum-opt (original specified) value: "
<< args_info.enum_opt_orig << endl;
}
if (args_info.secret_given)
cout << "Secret option was specified: " << args_info.secret_arg
<< endl;
cout << args_info.def_opt_arg << "! ";
cout << "Have a nice day! :-)" << endl ;
cmdline_parser_free (&args_info); /* release allocated memory */
return 0;
}
Now you can compile main1.cc and the cmdline1.c generated
by gengetopt and link all together to obtain sample1 executable:
gcc -c cmdline1.c
g++ -c main1.cc
g++ -o sample1 cmdline1.o main1.o
(Here we assume that getopt_long is included in the standard C library;
see Installation and No getopt_long).
Now let's try some tests with this program:
$ ./sample1 -s "hello" --int-opt 1234
This one is from a C++ program
Try to launch me with some options
(type sample1 --help for the complete list)
For example: ./sample1 *.* --funct-opt
Here are the options you passed...
You inserted hello for --str-opt option.
This is the integer you input: 1234.
The flag is off.
Have a nice day! :-)
You can also pass many file names to the command line (this also shows how flags work):
$ ./sample1 *.h -i -100 -x
This one is from a C++ program
Try to launch me with some options
(type sample1 --help for the complete list)
For example: ./sample1 *.* --funct-opt
Here are the options you passed...
file: cmdline1.h
file: cmdline2.h
file: cmdline.h
file: getopt.h
This is the integer you input: -100.
The flag is on.
Have a nice day! :-)
And if we try to omit the --int-opt (or -i), which is
required, we get an error:
$ ./sample1
This one is from a C++ program
Try to launch me with some options
(type sample1 --help for the complete list)
For example: ./sample1 *.* --funct-opt
sample1: `--int-opt' (`-i') option required!
Now, let's test the enumerated options, notice the use of a prefix for
specifying an acceptable value, and the difference between the actual
passed value and the one recorded in <option>_arg:
$ ./sample1 -i 10 --enum-opt h
...
enum-opt value: hello
enum-opt (original specified) value: h
...
While the next one raises an ambiguity error (between "bar"
and "bye"):
$ ./sample1 -i 10 --enum-opt b
...
./sample1: ambiguous argument, "b", for option `--enum-opt'
Here is the output of --help:
sample1 2.0
Usage: sample1 -iINT|--int-opt=INT [-h|--help] [-V|--version]
-sfilename|--str-opt=filename -mINT|--my-opt=INT [--flag-opt]
[-F|--funct-opt] --long-opt=LONG --def-opt=STRING [FILES]...
-h, --help Print help and exit
--full-help Print help, including hidden options, and exit
-V, --version Print version and exit
-s, --str-opt=filename A string option, for a filename
A brief text description before the other options.
-m, --my-opt=INT Another integer option, this time the description of
the option should be quite long to require
wrapping... possibly more than one wrapping :-)
especially if I
require a line break
-i, --int-opt=INT A int option
more involved options:
the following options
are more complex
--flag-opt A flag option (default=off)
-F, --funct-opt A function option
last option section:
--long-opt=LONG A long option
--def-opt=STRING A string option with default (default=`Hello')
--enum-opt=STRING A string option with list of values (possible
values="foo", "bar", "hello", "bye"
default=`hello')
-D, --dependant=INT option that depends on str-opt
An ending text.
Notice how filename is printed instead of STRING for the
option --str-opt (since typestr was used in the
sample1.ggo file) and how the description of --my-opt is
wrapped to 80 columns, and how the \n is actually interpreted
as a newline request. Moreover, since -S,--secret is
an hidden option (See Hidden options.) it is not printed;
if you wanted that to be printed, you should use --full-help.
Finally, notice how the text strings are printed in the help
output (and the empty line after the “more involved options” section
achieved with an empty text string).
If you're curious you may want to take a look at the generated C file cmdline1.c.
You may find other examples in /prefix/share/doc/gengetopt/examples or in the tests of the source tarbal.
This is the output of gengetopt --help:
gengetopt
This program generates a C function that uses getopt_long function
to parse the command line options, validate them and fill a struct.
Usage: gengetopt [OPTIONS]...
-h, --help Print help and exit
-V, --version Print version and exit
-i, --input=filename input file (default std input)
-f, --func-name=name name of generated function
(default=`cmdline_parser')
-a, --arg-struct-name=name name of generated args info struct
(default=`gengetopt_args_info')
-F, --file-name=name name of generated file (default=`cmdline')
--output-dir=path output directory
-c, --c-extension=ext extension of c file (default=`c')
-H, --header-extension=ext extension of header file (default=`h')
-l, --long-help long usage line in help
-u, --unamed-opts[=STRING] accept options without names (e.g., file names)
(default=`FILES')
The parser generated is thought to be used to parse the command line
arguments. However, you can also generate parsers for configuration files,
or strings that contain the arguments to parse, by using the following two
options.
-C, --conf-parser generate a config file parser
-S, --string-parser generate a string parser (the string contains the
command line)
-G, --include-getopt adds the code for getopt_long in the generated C
file
-n, --no-handle-help do not handle --help|-h automatically
-N, --no-handle-version do not handle --version|-V automatically
-e, --no-handle-error do not exit on errors
-g, --gen-version put gengetopt version in the generated file
(default=on)
--set-package=STRING set the package name (override package defined in
the .ggo file)
--set-version=STRING set the version number (override version defined
in the .ggo file)
--show-help show the output of --help instead of generating
code
--show-full-help show the output of --help (including hidden
options) instead of generating code
--show-version show the output of --version instead of
generating code
Please refer to the manual for further explanations.
The options should be clear; in particular:
--func-name--func-name is given, cmdline_parser is taken by default;
--output-dir--output-dir11 is given, the
files are generated in the current directory;
--arg-struct-namegengetopt_args_info)
--long-help--unamed-optssample1 *.h). You can
specify an optional description for these additional names (default is
FILES).
--no-handle-help--no-handle-version--no-handle-help (--no-handle-version) is given the
command line option --help|-h (--version|-V) is not
handled automatically, so the programmer will be able to print some
other information; then the function for printing the standard help
(version) response can be used; this function is called
<parser-name>_print_help (<parser-name>_print_version),
where <parser-name> is the name specified with --func-name
or the default, cmdline_parser.
--no-handle-error--no-handle-error is given, an error in the parsing does not
provoke the exit of the program; instead, since the parser function, in
case of an error, returns a value different 0, the program can print a
help message, as gengetopt itself does in case of an error (try it!).
--gen-version--conf-parser--string-parser--include-getoptgetopt_long into the generated parser C file.
This will make your generated parser much bigger, but it will be
compiled in any system, even if getopt_long is not part of the C
library where your program is being compiled. See also No getopt_long.
--show-help--show-full-help--show-version--help,
--full-help and --version command lines without
generating any code, See Automatically added options.
For instance, I use the --show-help option to generate a
texinfo file with the output of help (this also shows an example of
use of --set-package and --set-version):
../src/gengetopt --show-help -i ../src/cmdline.ggo \
--set-package="gengetopt" \
--set-version="" > help_output.texinfo
You may have already guessed it: gengetopt uses gengetopt itself for
command line options, and its specification file is cmdline.ggo
in the source directory. In particular the command line for gengetopt
itself is generated with the following command:
gengetopt --input=cmdline.ggo --no-handle-version \
--no-handle-help --no-handle-error
Indeed when --help|-h is passed on the command line, gengetopt will call
cmdline_parser_print_help() and then the lines for reporting bugs. When
--version|-V is passed, it will call cmdline_parser_print_version() and
then prints a copyright. If an error occurs it prints a message on the
screen:
$ ./gengetopt --zzzz
./gengetopt: unrecognized option `--zzzz'
Run gengetopt --help to see the list of options.
An argument is an element of the argv array passed into
your C or C++ program by your operating system.
An option is an argument that begins with -, or --.
A value is an argument, or part of an argument, that is associated with a particular option (an option may also not accept any value). For example, in
> ls --width=80
ls is called with one argument, --width=80,
which is an option that has a value, 80, while in
> ls --width 80
ls is called with two arguments, --width,
which is an option, and 80 which might or might not be a value.
In this case, whether the 80 is treated as a value associated
with the preceding --width option, or as the name of a file to
list depends on how ls parses the --width option.
The order in which options are specified is usually unimportant:
> ls -a -l
> ls -l -a
both do exactly the same thing.
An parameter is an argument that is not an option. For example, in
> cp --archive source dest
cp is called with three arguments, the option
--archive, the parameter source, and the parameter
dest. Unlike options, the order in which parameters are
specified usually is important:
> cp --archive --verbose source dest
> cp --verbose --archive source dest
> cp --archive source --verbose dest
> cp --archive --verbose dest source
The first three cp commands do the same thing, but the fourth one is completely different.
If you're new to Gengetopt, you may wish to skip the rest of this section. It goes into more detail about different sorts of options, and how they are parsed.
Note that some parameters may begin with - or --. Equivalently, not all arguments that begin with - or -- are options. Consider
> ls -- -file
> tar -c -f - . > ../foo.tar
The ls command has two arguments; the first
argument, -- is ignored by ls, but causes the
-file argument to be interpreted as a parameter. The tar
command has four arguments. The -c argument tells tar to
create an archive; the -f argument, which takes a value,
-, tells tar that the archive should be written onto the standard
output, and the fourth argument, ., tells tar what directories to
include in the archive. (The remaining two items, > and
../foo.tar, tell the shell to redirect the tar
command's output to the file ../foo.tar. The tar command
doesn't even see them.)
The GNU convention is that - by itself is always interpreted as a value or parameter, while the first -- by itself is always ignored, but causes all subsequent arguments to be interpreted as parameters. Gengetopt always behaves this way.
A short option is an option that begins with -. Not including the leading dash, short options must be one character long:
> ls -a -l -t --width=80
The -a, -l, and -t options are all short options. Multiple short options may be combined into a single argument:
> ls -alt --width=80
is equivalent to the above example.
A long option is an option that begins with - or --. Ignoring the leading punctuation, long options may be one or more characters long:
> ls --all -fs
The ls command has two arguments; the long option --all, and the pair of short options -fs.
Long options need not have synonymous short options; after all, complex programs like cc have more long options than there are valid short option characters; it wouldn't be possible to assign a short option to each of them. Short options are encouraged, but not required, to have a synonymous long option.
Long options may be abbreviated, as long as the abbreviation is not ambiguous. Gengetopt automatically treats unambiguous abbreviations as synonyms.
Short options may have values just like long options, but if several short options are grouped together into one argument, only the last one may have a value. Values in the same argument as a long option are delimited by an equals sign, values in the same argument as a short option are not:
> ls --width 60 # ok, value is "60"
> ls --width=60 # ok, value is "60"
> ls -w60 # ok, value is "60"
> ls -w 60 # ok, value is "60"
> ls -w=60 # unexpected, value is "=60"
> ls -T7 -w60 # ok, value for -T is 7, value for -w is 60
> ls -T7w60 # unexpected, value for -T is "7w60", no -w at all
A required option must be present, otherwise an error will be raised.
A multiple option is an option that may appear more than once on the command line. Gengetopt would create a tidy array for multiple options (see Multiple Options, for further details about dealing with multiple options).
It is also possible to group options; options belonging to a group are
considered in mutual exclusion. In order to use this feature, first the
group has to be defined, and then a groupoption can be defined. A
groupoption has basically the same syntax of a standard option, apart
that the required flag must not be specified (it would not make sense,
since the options of the same group are mutual exclusive) and the group
to which the option belongs has to be specified.
defgroup "<group name>" {groupdesc="<group description>"} {yes}
groupoption <long> <short> <desc> <argtype> group="<group name>" \
{argoptional} {multiple}
If a group is defined as required, then one (but only one) option belonging to the group has to be specified.
Here's an example (taken from the test test_group_cmd.ggo):
defgroup "my grp2"
defgroup "grp1" groupdesc="an option of this group is required" required
groupoption "opta" a "string a" group="grp1" multiple
groupoption "optA" A "string A" string group="grp1" argoptional
groupoption "optAmul" M "string M" string group="grp1" argoptional multiple
groupoption "optb" b "string b" group="grp1"
groupoption "optc" - "string c" group="my grp2"
groupoption "optd" d "string d" group="my grp2"
The group grp1 is required, so either --opta or
--optb has to be specified (but only one of them). Here's the
output of some executions:
$ ./test_groups
test_groups: 0 options of group grp1 were given. One is required
$ ./test_groups -a OK
$ ./test_groups -a -a OK (the same option given twice)
$ ./test_groups -a -b
test_groups: 2 options of group grp1 were given. One is required
$ ./test_groups -a -c OK
$ ./test_groups -a --optc -d
test_groups: 2 options of group my grp2 were given. At most one is required
It is often useful to specify command line options directly in a
configuration file, so that the value of some options are read from
this file if they are not given as command line options. When the
command line option -C|--conf-parser is given to gengetopt,
apart from the standard command line option parser, also this
additional parser is generated (its name is
<commandline_parser>_configfile):
int
<cmd_parser_name>_configfile (char * const filename,
struct gengetopt_args_info *args_info,
int override,
int initialize,
int check_required);
The parameter override tells whether the values read in the
configuration file have to override those specified at the command line.
The initialize tells whether the args_info struct has to be
initialize.
IMPORTANT: you have to explicitly set initialize to true (i.e.,
different from 0) if you call the config file parser before the standard
command line option parser, otherwise unpredictable results may show.
The check_required tells whether the check for required options
must be performed or not.
If you call the config file parser before the standard command line option parser and then you want to call the standard command line parser you MUST use this second version, passing 0 for initialized, so that collected values from the config file are not lost:
int
<cmd_parser_name>2 (int argc,
char * const *argv,
struct gengetopt_args_info *args_info,
int override,
int initialize,
int check_required);
Notice, that with this version you can also specify whether the options
passed at the command line must override the ones read from the config
file. If you set override to 0, and a command line option is
given that has already been read from the config file, an error will be
raised. Moreover, you have to specify whether the check for missing
required options must be performed or not. This concerns also options
of a required group (Group options).
If you decide not to request the check for required option, you can test it manually, after the command line parsing returns by using the following generated function:
int
<cmd_parser_name>_required (struct gengetopt_args_info *args_info,
const char *program_name);
where program_name is the name of your executable (usually you
should pass argv[0] as argument). If the function returns a
value different from 0, then some required options are missing. An
error has already been printed by this function. This concerns also
options of a required group (Group options).
The config file has the following simple syntax: lines starting with # are considered comments and:
<option_name> = {<option_val>}
or simply (if the option does not take an argument):
<option_name>
which means that option_name is given, and if it accepts an argument,
then its value is option_val. The = is not mandatory.
For instance here's a program that uses this feature (this is the test test_conf_parser):
/* test_conf_parser.c test */
/* test all kinds of options and the conf file parser */
#include <stdlib.h>
#include <stdio.h>
#include "test_conf_parser_cmd.h"
static struct my_args_info args_info;
int
main (int argc, char **argv)
{
int i;
int result = 0;
if (test_conf_parser_cmd_parser (argc, argv, &args_info) != 0) {
result = 1;
goto stop;
}
/* override cmd options, but do not initialize args_info, check for required options */
if (test_conf_parser_cmd_parser_configfile
(args_info.conf_file_arg, &args_info, 1, 0, 1) != 0)
{
result = 1;
goto stop;
}
printf ("value of required: %s\n", args_info.required_arg);
printf ("value of string: %s\n", args_info.string_arg);
printf ("value of no-short_given: %d\n", args_info.no_short_given);
printf ("value of int: %d\n", args_info.int_arg);
printf ("value of float: %f\n", args_info.float_arg);
printf ("value of multi-string_given: %d\n", args_info.multi_string_given);
for (i = 0; i < args_info.multi_string_given; ++i)
printf (" value of multi-string: %s\n", args_info.multi_string_arg [i]);
printf ("value of multi-string-def_given: %d\n",
args_info.multi_string_def_given);
for (i = 0; i < args_info.multi_string_def_given; ++i)
printf (" value of multi-string-def: %s\n",
args_info.multi_string_def_arg [i]);
if (!args_info.multi_string_def_given && args_info.multi_string_def_arg [0])
printf ("default value of multi-string-def: %s\n",
args_info.multi_string_def_arg [0]);
printf ("value of opta: %s\n", args_info.opta_arg);
printf ("noarg given %d times\n", args_info.noarg_given);
printf ("noarg_noshort given %d times\n", args_info.noarg_noshort_given);
printf ("opt-arg given: %d\n", args_info.opt_arg_given);
printf ("opt-arg value: %s\n", (args_info.opt_arg_arg ? args_info.opt_arg_arg : "not given"));
if (args_info.file_save_given) {
if (test_conf_parser_cmd_parser_file_save (args_info.file_save_arg, &args_info) == EXIT_FAILURE)
result = 1;
else
printf ("saved configuration file %s\n", args_info.file_save_arg);
}
stop:
test_conf_parser_cmd_parser_free (&args_info);
return result;
}
So if we use the following config file
# required option
required "this is a test"
float 3.14
no-short
string another
and we run test_conf_parser like that, we will have
./test_conf_parser -r bar -i 100 --float 2.14 --conf-file test_conf.conf
value of required: this is a test
value of string: another
value of no-short: 1
value of int: 100
value of float: 3.140000
If, instead we call the test_conf_parser_cmd_parser_configfile with 0
for override argument, we get the following result
value of required: bar
value of string: another
value of no-short: 1
value of int: 100
value of float: 2.140000
This second example use the second version of the command line parser: first call the configuration file parser and then the command line parser (the command line options will override the configuration file options):
/* test_conf_parser_ov2.c test */
/* test all kinds of options and the conf file parser */
/* differently from test_conf_parser_ov.c, first scan the conf file and
then the command line */
#include <stdlib.h>
#include <stdio.h>
#include "test_conf_parser_cmd.h"
static struct my_args_info args_info;
int
main (int argc, char **argv)
{
/* do not override command line options, initialize args_info */
if (test_conf_parser_cmd_parser_configfile
("./test_conf2.conf", &args_info, 0, 1, 0) != 0)
exit(1);
if (test_conf_parser_cmd_parser2 (argc, argv, &args_info, 1, 0, 1) != 0)
exit(1) ;
printf ("value of required: %s\n", args_info.required_arg);
printf ("value of string: %s\n", args_info.string_arg);
printf ("value of no-short_given: %d\n", args_info.no_short_given);
printf ("value of int: %d\n", args_info.int_arg);
printf ("value of float: %f\n", args_info.float_arg);
test_conf_parser_cmd_parser_free (&args_info);
return 0;
}
This is an invocation and its results:
./test_conf_parser_ov2 -r "bar" --float 2.14 -i 100
value of required: bar
value of string: another
value of no-short: 1
value of int: 100
value of float: 2.140000
The generated config file parser function uses the constant
CONFIG_FILE_LINE_SIZE to read each line of the configuration
file. By default this constant is set to 2048 that should be
enough for most applications. If your application uses configuration
files with lines that are longer, you can compile the generated C file
by specifying an explicit value for this constant with the -D
command line option of gcc.
If an option is specified as multiple, then it can be specified multiple
times at command line. In this case, say the option is called foo, the
generated foo_given field in the args structure contains the number of
times it was specified and the generated field foo_arg is an array
containing all the values that were specified for this option.
Notice that if a default value is specified for a multiple option, that
value is assigned to the option only if no other value is specified on
the command line (and the corresponding _given field will be set to 1),
i.e., a default value IS NOT always part of the values of a multiple
option.
For instance, if the gengetopt file is as follows
# test options that can be given more than once
option "string" s "string option" string optional multiple
option "int" i "int option" int optional multiple
Then the command line options can be collected like that
Then if this program is called with the following command line options
/* test options that can be given more than once */
#include <stdlib.h>
#include <stdio.h>
#include "test_multiple_cmd.h"
static struct gengetopt_args_info args_info;
int
main (int argc, char **argv)
{
int i = 0;
if (test_multiple_cmd_parser (argc, argv, &args_info) != 0)
exit(1) ;
for (i = 0; i < args_info.string_given; ++i)
printf ("passed string: %s\n", args_info.string_arg[i]);
for (i = 0; i < args_info.int_given; ++i)
printf ("passed int: %d\n", args_info.int_arg[i]);
return 0;
}
The output of the program will be
passed string: world
passed string: hello
passed string: bar
passed string: foo
passed int: 200
passed int: 100
You can also pass arguments to a multiple option separated by commas (if
you need to actually specify the comma operator as part of the argument
you can escape it with \), as in the following:
./test_multiple -s"foo","bar","hello" -i100,200 -s "world"
You can specify the number of occurrences of multiple options by using
the following syntax (that must be given after the multiple
keyword):
(number)number times
(number1-number2)number1 times and no more than number2 times
(number-)number times
(-number)number times
Here are some examples:
option "string" s "string option" string optional multiple(4)
option "string" s "string option" string optional multiple(1-4)
option "string" s "string option" string optional multiple(-5)
Notice that this is independent from the required flag.
The parsers generated by gengetopt (indeed the C and header files) are
self-contained and different parsers can be linked in the same
program, without interferences. This is useful, e.g., in cases where
a specific command line option argument has a complex syntax that
accepts options itself according to terminology already defined, the
one handled by getopt_long, see Terminology. Another
case when multiple parsers can be useful is when your command behaves
differently according to a specific command line option.
Obviously there exists only one instance of command line arguments
passed to the main function (namely the variables argc
and argv) so passing the same arguments to different command
line parsers is likely to generate errors: the different command line
parsers are likely to have different syntaxes for accepted options.
For this reason gengetopt can generate parser functions that take a
string containing the further options to parse, instead of taking an
array. This additional parser will have the parser name and the
suffix _string. If you want these additional parsers to be
generated you have to pass the command line option
-S|--string-parser to gengetopt (see Invoking gengetopt).
The two functions will be:
int <parser_name>_string (const char *cmdline,
struct test_first_cmdline_cmd_struct *args_info,
const char *prog_name);
int <parser_name>_string2 (const char *cmdline,
struct test_first_cmdline_cmd_struct *args_info,
const char *prog_name,
int override, int initialize, int check_required);
The second one allows you to specify more details about the parsing (this is the same as for configuration files, thus we refer to that section for the details of the two functions and default values, see Configuration files).
Of course, these functions can be used in general to simulate the invocation of a program with specific command line options (stored in the first string argument), or in general to parse options that are all stored in a string (instead of a vector).
The first argument of these parsers is a string containing the options
to parse (remember that this must respect the option format handled by
getopt_long, see Terminology). The second one is the
pointer to the struct that will be filled with passed options and
arguments, as usual. The third option is the program name: this will
be used when errors have to be printed. This last argument can be
null: in this case, the first element of the first string argument is
considered the program name.
Let's show these functionalities with an example. Consider a program that accepts two command line options (required in this case):
# test for multiple parsers, this is the main file
# test_main_cmdline_cmd.ggo
option "first-cmd" F "the first command line to parse" required \
typestr="first command" string multiple
option "second-cmd" S "the second command line to parse" required \
typestr="second command" string multiple
These two options accept strings as argument that in turn are considered command line arguments, according to specific syntaxes. The first one is:
# test for multiple parsers, this is the first command line file
# test_first_cmdline_cmd.ggostr
option "option-a" a "option a of the first command line to parse"
optional int option "multi" M \
"multiple option of the first command line to parse" \
optional string multiple
and the second one is:
# test for multiple parsers, this is the second command line file
# test_second_cmdline_cmd.ggostr
option "option-a" a "option a of the second command line to parse" \
optional string
option "option-b" b "option a of the second command line to parse" \
optional string
option "my-multi" M \
"multiple option of the second command line to parse" \
optional string multiple
These last two files are processed with gengetopt using the
--string-parser. Let's put everything together in this main
file:
#include <stdio.h>
#include <stdlib.h>
#include "test_main_cmdline_cmd.h"
#include "test_first_cmdline_cmd.h"
#include "test_second_cmdline_cmd.h"
int
main(int argc, char **argv)
{
struct gengetopt_args_info main_args_info;
struct test_first_cmdline_cmd_struct first_args_info;
struct test_second_cmdline_cmd_struct second_args_info;
int exit_code = 0, i, j;
if (test_main_cmdline_cmd_parser (argc, argv, &main_args_info) != 0) {
exit_code = 1;
return exit_code;
}
for (j = 0; j < main_args_info.second_cmd_given; ++j) {
printf("second cmdline: %s\n", main_args_info.second_cmd_arg[j]);
if (test_second_cmdline_cmd_parser_string
(main_args_info.second_cmd_arg[j], &second_args_info, argv[0]) == 0) {
if (second_args_info.option_a_given)
printf(" --option-a: %s\n", second_args_info.option_a_arg);
if (second_args_info.option_b_given)
printf(" --option-b: %s\n", second_args_info.option_b_arg);
for (i = 0; i < second_args_info.my_multi_given; ++i)
printf(" --my-multi: %s\n", second_args_info.my_multi_arg[i]);
test_second_cmdline_cmd_parser_free (&second_args_info);
}
}
for (j = 0; j < main_args_info.first_cmd_given; ++j) {
printf("first cmdline: %s\n", main_args_info.first_cmd_arg[j]);
if (test_first_cmdline_cmd_parser_string
(main_args_info.first_cmd_arg[j], &first_args_info, argv[0]) == 0) {
if (first_args_info.option_a_given)
printf(" --option-a: %d\n", first_args_info.option_a_arg);
for (i = 0; i < first_args_info.multi_given; ++i)
printf(" --multi: %s\n", first_args_info.multi_arg[i]);
test_first_cmdline_cmd_parser_free (&first_args_info);
}
}
test_main_cmdline_cmd_parser_free (&main_args_info);
return exit_code;
}
Notice that in the for loops we always free the elements of the
argument structures in order to avoid memory leaks.
Now if you can run this program as follows (notice that we use the comma
separated arguments for multiple option arguments but we escape it with
\ because otherwise, e.g., 200 and 300 would be intended as
further arguments of --first-cmd instead of --multi, see
Multiple Options):
./test_multiple_parsers \
--first-cmd="-M400 -a10 --multi 100\,200\,300" \
--second-cmd="-a20 -b10 --my-multi=a\,b\,c\,d\,e\,f" \
-F"-M500 -M600" -S"--my-multi g"
second cmdline: -a20 -b10 --my-multi=a,b,c,d,e,f
--option-a: 20
--option-b: 10
--my-multi: a
--my-multi: b
--my-multi: c
--my-multi: d
--my-multi: e
--my-multi: f
second cmdline: --my-multi g
--my-multi: g
first cmdline: -M400 -a10 --multi 100,200,300
--option-a: 10
--multi: 400
--multi: 100
--multi: 200
--multi: 300
first cmdline: -M500 -M600
--multi: 500
--multi: 600
If you use gengetopt to generate C functions for parsing command line
arguments you have to know that these generated functions use
getopt_long to actually read the command line and parsing it.
This function is typically part of the standard C library, but some
implementations may not include it. If you want your program to be
portable on several systems, and be compilable with many C compilers,
you can rely on one of the following solutions.
getopt_long code into the generated parserSince version 2.17, gengetopt can include into the generated C parser
file the code of getopt_long, so that the include code will be
used to actually parse the command line arguments, instead of that taken
from the C library.
This solution is actually quite easy, but it has two main drawbacks:
getopt_long
of the C library
It is up to you to choose between this and the automake/autoconf based solution.
Actually, this solution has the advantage that your program won't behave
strangely when used with another implementation of getopt_long.
I prefer the automake/autoconf based solution, as described in Use automake/autoconf, which is also the one I adopt for gengetopt itself.
getopt_longBut this is not a problem: we provide C files that actually implement getopt_long function: getopt.c getopt1.c and gnugetopt.h. You'll find these files in the <install prefix>/share/gengetopt directory where <install prefix> is the one you specified during compilation. If no prefix had been specified, /usr/local is the default. If you downloaded gengetopt in binary form prefix will probably be /usr/local or /usr.
You can rename gnugetopt.h to getopt.h and then simply compile these files and link them to the executable of you program. However, if you use automake and autoconf here's a more elegant solution: you should download the macro you find at this URL:
http://www.gnu.org/software/ac-archive/m4source/adl_func_getopt_long.m4
and add it to your acinclude.m4. You can find this macro also in the acinclude.m4 in the sources of gengetopt.
This macro checks if getopt_long function is in C library;
if it is not then it adds getopt.o and getopt1.o to the objects files
that will be linked to your executable (LIBOBJS).
Then in Makefile.am of your source directory you have to add the contents
of LIBOBJS to the LDADD of the program that has to use getopt_long;
e.g., if the program foo has to use getopt_long, you have to add
the following line
foo_LDADD = @LIBOBJS@
Now these files will be compiled and linked to your program only if necessary.
Moreover you have to add getopt.c getopt1.c and
gnugetopt.h to your distribution. Note that it is not necessary
to put these file names among the foo_SOURCES contents), but you have to
add gnugetopt.h to EXTRA_DIST:
EXTRA_DIST = gnugetopt.h
You may want to take a look at gengetopt's configure.in and src/Makefile.am: they both use the techniques described here.
If you find a bug in gengetopt, please send electronic mail to
bug-gengetopt at gnu dot org
Include the version number, which you can find by running `gengetopt --version'. Also include in your message the output that the program produced and the output you expected.
If you have other questions, comments or suggestions about gengetopt, contact the author via electronic mail (find the address at http://www.lorenzobettini.it). The author will try to help you out, although he may not have time to fix your problems.
The list of todos in the TODO.
It seems that getopt_long, at least the version in the GNU
library, if invoked with different argv arrays, might access
memory in a bad way leading to crashes or unexpected behaviors. This
happens because it keeps pointers to locations of the previous arrays
if not initiliazed each time by setting optind =
012.
Unfortunately this initialization behavior seems to be part only of
the implementation of GNU library and actually it is not documented
(you can see it by taking a look into the source of getopt.c);
other implementations of getopt_long might not be affected by
this problem; alternatively, as reported by a user, optind = 0
leads some getopt_long implementations to consider the program
name as a command line option (since it is in position 0), which is
bad anyway!
Probably this is usually not a problem since you usually parse only the
command line, thus you only invoke the command line parser only once,
and only with one instance of array (i.e., the argv passed to
main). However, it can lead to problems when you use advanced
features, as in the case of configuration file parsing (see
Configuration files) and multiple parsers (see String Parsers and Multiple Parsers).
To deal with this problem, in case one uses configuration parsers
(-C,--conf-parser) or string parsers
(-S,--string-parser) a customized version of
getopt_long, called indeed
custom_getopt_long is
inserted in the generated C file. This version does not suffer from
the problem above (and of course does not interfere with the standard
getopt_long, which will be used to parse the actual command
line arguments).
Of course this is transparent to the programmer, and we report this
detail here only because the inserted custom_getopt_long will
add about 20k of C code in the generated file, so don't panic if you
start to use configuration or string parsers and your program gets a
little bigger than before :-).
The following mailing lists are available:
help-gengetopt at gnu dot org
for generic discussions about the program and for asking for help about it (open mailing list), http://mail.gnu.org/mailman/listinfo/help-gengetopt
info-gengetopt at gnu dot org
for receiving information about new releases and features (read-only mailing list), http://mail.gnu.org/mailman/listinfo/info-gengetopt.
If you want to subscribe to a mailing list just go to the URL and follow the instructions, or send me an e-mail and I'll subscribe you.
--full-help: Basic Usage-C,--conf-parser: Configuration files-h,--help: Basic Usage-S,--string-parser: String Parsers and Multiple Parsers-V,--version: Basic Usagecustom_getopt_long: Getopt and subsequent calls[1] Command lines that are
too long are split into multiple indented lines separated by a \.
Of course these commands are to be given in one line only, anyway.
[2] Since version 2.18
[3] Since version 2.15.
[4] Since version 2.16.
[5] This holds since version 2.15: in previous versions the option specifications had to be given in a fixed order.
[6] Since version 2.16.
[7] Since version 2.18.
[8] The <option>_orig was introduced in the release
2.14.
[9] These
strings and the <option>_help were introduced in the release
2.17.
[10] This function was introduced in the release 2.14.
[11] Since version 2.17.
[12] optind is the global variable in getopt
implementation that is the index in ARGV of the next element to be
scanned. This is used for communication to and from the caller and
for communication between successive calls to getopt_long.