2 Basic Usage
The command line options, which have to be handled by gengetopt generated function, are specified in a file (typically with .ggo extension). This file consists of sentences with the formats shown below (these sentences are allowed to span more than one line). Statements in {} are optional (the
optionsentences need not to be given in separate lines):package "<packname>" version "<version>" purpose "<purpose>" usage "<usage>" description "<description>" args "<command line options>" option <long> <short> "<desc>" {details="<detailed description>"} {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:
package- This has the precedence over
PACKAGEgenerated by autoconf. Optional.version- This has the precedence over
VERSIONgenerated by autoconf. Optional.purpose- What the program does (even on more than one line), it will be printed with the help, before the usage string. Optional.
usage- The “Usage” string that will be printed with the help5. If not specified, it will be generated automatically. Optional.
description- The “Description” string that will be printed with the help6, after the usage string. Optional.
args- With
args7 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. Optional.
long- The long option, a double quoted string with upper and lower case characters, digits, a dash (
-) 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- The short option, a single upper or lower case char, or a digit. If a
-is specified, then no short option is considered for the long option (thus long options with no associated short options are allowed). Since version 2.22 you can also specify?as the short option.desc- This description will be printed during the output of
--help. Wrapping will be automatically performed.details- This is an extended description string for the option that will be printed (after the option) during the output of
--detailed-help8, which will be automatically generated. Thus, these further details will NOT be printed with--help. Wrapping will be automatically performed. Optional.argtypestring,int,short,long,float,double,longdoubleorlonglong. If the option is an enumerated one (see Options with enumerated values) the type can also beenum. If no type is specified the option does not accept an argument.typestr- a description for the type of the values for the option. This will be used during the output of
--help(e.g.,"filename"instead of simplySTRING, or"portnumber"instead of simplyINT).values- a list of strings containing all the possible values that can be passed to the option. If not specified, the type is considered string9. For this kind of options, the type can also be
enum. More on this feature can be found in Options with enumerated values.default- an optional default value for the option. The value must always be specified as a double quoted string.
dependon- this option depends on another option (whose long name description is specified). If this option is given at command line but not the option it depends on, an error will be generated.
requiredrequiredoroptional. 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 keywordsyesorno. You can still use these keywords but their use is not advised since they are not much explicative.If not specified, an option is considered mandatory; if you do not want this behavior, you can require that by default options are considered optional, by using the command line option
--default-optional10.argoptional- If this flag is specified then this option has an argument that is optional. In this case, when you specify the argument at command line, please use
=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:-B15or--bar=15, and NOT the following one-B 15nor--bar 15.By using this specification together with
defaultyou 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.multiple- If this flag is specified then this option can be specified more than once at command line; all the values for this option are stored in an array. You can also specify the number of occurrences that a multiple option must be specified. Notice that this is independent from the
requiredflag. See Multiple Options.hidden- If an option is “hidden” it will not appear in the output of
--helpbut it can still be specified at command line11. In case hidden options are used, the command line option--full-helpwill also be generated. This will print also the hidden options12. If there's an option withdetails, then also--detailed-help13 will be automatically generated; if one then specifies--detailed-helpalso hidden options will be printed (besides the details for options).on/offonoroff. This is the state of the flag when the program starts. If user specifies the option, the flag toggles.For strings (delimited by
") the following convention is adopted14: a string spanning more than one line will be interpreted with the corresponding line breaks; if the line break is not desired one can use the backslash\to break the line without inserting a line break. A line break in a string can also be inserted with the string\n. Here are some examples:"This string will be interpreted into two lines exactly as it is" "This string is specified with two lines \ but interpreted as specified in only one line \ i.e., without explicit line break" "This string\nwill have a line break"Moreover, if the character
"must be specified in the string, it will have to be escaped with the backslash15:"This string contains \"a quoted string\" inside"The part that must be provided in the correct order is
option <long> <short> "<desc>"while the other specifications can be given in any order16. Thus, for instance
option <long> <short> "<desc>" {argtype} {typestr="<type descr>"}is the same as
option <long> <short> "<desc>" {typestr="<type descr>"} {argtype}Comments begin with
#in any place (but in strings) of the line and ends in the end of line.Notice that the options
-h,--helpand-V,--versionare added automatically; however, if you specify an option yourself that hashas short form, then only--helpis added17. The same holds for-V,--version.In case hidden options are used, See Hidden options, the command line option
--full-helpwill also be generated. This will print also the hidden options18.If there's at least one option with
details, the command line option--detailed-helpwill also be generated. This will print also the details for options and hidden options19.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
sectiondescis 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 usetext, explained in the next paragraph.You can insert, among options, a textual string that will be printed in the output of
--help20: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
valuesthat can be passed to an option (if the type is not specified, the option has typestring). More on this feature can be found in Options with enumerated values. 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)
# Name of your program package "sample1" # don't use package if you're using automake # Version of your program version "2.0" # don't use version if you're using automake # Options 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 yes 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 details="\nA function option is basically an option with no argument.\ It can be used, e.g., to specify a specific behavior for a program. Well, this further explanation is quite useless, but it's only to \ show an example of an option with details, \ which will be printed only when --detailed-help is given \ at the command line." 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.ggoBy 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-optsThe option
--unamed-optsallows 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 isFILES).In cmdline1.h you'll find the generated C struct:
/** @file cmdline1.h * @brief The header file for the command line option parser * generated by GNU Gengetopt version 2.22 * http://www.gnu.org/software/gengetopt. * DO NOT modify this file, since it can be overwritten * @author GNU Gengetopt by Lorenzo Bettini */ #ifndef CMDLINE1_H #define CMDLINE1_H /* If we use autoconf. */ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include <stdio.h> /* for FILE */ #ifdef __cplusplus extern "C" { #endif /* __cplusplus */ #ifndef CMDLINE_PARSER_PACKAGE /** @brief the program name */ #define CMDLINE_PARSER_PACKAGE "sample1" #endif #ifndef CMDLINE_PARSER_VERSION /** @brief the program version */ #define CMDLINE_PARSER_VERSION "2.0" #endif /** @brief Where the command line options are stored */ struct gengetopt_args_info { const char *help_help; /**< @brief Print help and exit help description. */ const char *detailed_help_help; /**< @brief Print help, including all details and hidden options, and exit help description. */ const char *full_help_help; /**< @brief Print help, including hidden options, and exit help description. */ const char *version_help; /**< @brief Print version and exit help description. */ char * str_opt_arg; /**< @brief A string option, for a filename. */ char * str_opt_orig; /**< @brief A string option, for a filename original value given at command line. */ const char *str_opt_help; /**< @brief A string option, for a filename help description. */ int my_opt_arg; /**< @brief 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; /**< @brief 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; /**< @brief 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; /**< @brief A int option. */ char * int_opt_orig; /**< @brief A int option original value given at command line. */ const char *int_opt_help; /**< @brief A int option help description. */ int flag_opt_flag; /**< @brief A flag option (default=off). */ const char *flag_opt_help; /**< @brief A flag option help description. */ const char *funct_opt_help; /**< @brief A function option help description. */ long long_opt_arg; /**< @brief A long option. */ char * long_opt_orig; /**< @brief A long option original value given at command line. */ const char *long_opt_help; /**< @brief A long option help description. */ char * def_opt_arg; /**< @brief A string option with default (default='Hello'). */ char * def_opt_orig; /**< @brief A string option with default original value given at command line. */ const char *def_opt_help; /**< @brief A string option with default help description. */ char * enum_opt_arg; /**< @brief A string option with list of values (default='hello'). */ char * enum_opt_orig; /**< @brief A string option with list of values original value given at command line. */ const char *enum_opt_help; /**< @brief A string option with list of values help description. */ int secret_arg; /**< @brief hidden option will not appear in --help. */ char * secret_orig; /**< @brief hidden option will not appear in --help original value given at command line. */ const char *secret_help; /**< @brief hidden option will not appear in --help help description. */ int dependant_arg; /**< @brief option that depends on str-opt. */ char * dependant_orig; /**< @brief option that depends on str-opt original value given at command line. */ const char *dependant_help; /**< @brief option that depends on str-opt help description. */ unsigned int help_given ; /**< @brief Whether help was given. */ unsigned int detailed_help_given ; /**< @brief Whether detailed-help was given. */ unsigned int full_help_given ; /**< @brief Whether full-help was given. */ unsigned int version_given ; /**< @brief Whether version was given. */ unsigned int str_opt_given ; /**< @brief Whether str-opt was given. */ unsigned int my_opt_given ; /**< @brief Whether my-opt was given. */ unsigned int int_opt_given ; /**< @brief Whether int-opt was given. */ unsigned int flag_opt_given ; /**< @brief Whether flag-opt was given. */ unsigned int funct_opt_given ; /**< @brief Whether funct-opt was given. */ unsigned int long_opt_given ; /**< @brief Whether long-opt was given. */ unsigned int def_opt_given ; /**< @brief Whether def-opt was given. */ unsigned int enum_opt_given ; /**< @brief Whether enum-opt was given. */ unsigned int secret_given ; /**< @brief Whether secret was given. */ unsigned int dependant_given ; /**< @brief Whether dependant was given. */ char **inputs ; /**< @brief unamed options (options without names) */ unsigned inputs_num ; /**< @brief unamed options number */ } ; /** @brief The additional parameters to pass to parser functions */ struct cmdline_parser_params { int override; /**< @brief whether to override possibly already present options (default 0) */ int initialize; /**< @brief whether to initialize the option structure gengetopt_args_info (default 1) */ int check_required; /**< @brief whether to check that all required options were provided (default 1) */ int check_ambiguity; /**< @brief whether to check for options already specified in the option structure gengetopt_args_info (default 0) */ int print_errors; /**< @brief whether getopt_long should print an error message for a bad option (default 1) */ } ; /** @brief the purpose string of the program */ extern const char *gengetopt_args_info_purpose; /** @brief the usage string of the program */ extern const char *gengetopt_args_info_usage; /** @brief all the lines making the help output */ extern const char *gengetopt_args_info_help[]; /** @brief all the lines making the full help output (including hidden options) */ extern const char *gengetopt_args_info_full_help[]; /** @brief all the lines making the detailed help output (including hidden options and details) */ extern const char *gengetopt_args_info_detailed_help[]; /** * The command line parser * @param argc the number of command line options * @param argv the command line options * @param args_info the structure where option information will be stored * @return 0 if everything went fine, NON 0 if an error took place */ int cmdline_parser (int argc, char * const *argv, struct gengetopt_args_info *args_info); /** * The command line parser (version with additional parameters - deprecated) * @param argc the number of command line options * @param argv the command line options * @param args_info the structure where option information will be stored * @param override whether to override possibly already present options * @param initialize whether to initialize the option structure my_args_info * @param check_required whether to check that all required options were provided * @return 0 if everything went fine, NON 0 if an error took place * @deprecated use cmdline_parser_ext() instead */ int cmdline_parser2 (int argc, char * const *argv, struct gengetopt_args_info *args_info, int override, int initialize, int check_required); /** * The command line parser (version with additional parameters) * @param argc the number of command line options * @param argv the command line options * @param args_info the structure where option information will be stored * @param params additional parameters for the parser * @return 0 if everything went fine, NON 0 if an error took place */ int cmdline_parser_ext (int argc, char * const *argv, struct gengetopt_args_info *args_info, struct cmdline_parser_params *params); /** * Save the contents of the option struct into an already open FILE stream. * @param outfile the stream where to dump options * @param args_info the option struct to dump * @return 0 if everything went fine, NON 0 if an error took place */ int cmdline_parser_dump(FILE *outfile, struct gengetopt_args_info *args_info); /** * Save the contents of the option struct into a (text) file. * This file can be read by the config file parser (if generated by gengetopt) * @param filename the file where to save * @param args_info the option struct to save * @return 0 if everything went fine, NON 0 if an error took place */ int cmdline_parser_file_save(const char *filename, struct gengetopt_args_info *args_info); /** * Print the help */ void cmdline_parser_print_help(void); /** * Print the full help (including hidden options) */ void cmdline_parser_print_full_help(void); /** * Print the detailed help (including hidden options and details) */ void cmdline_parser_print_detailed_help(void); /** * Print the version */ void cmdline_parser_print_version(void); /** * Initializes all the fields a cmdline_parser_params structure * to their default values * @param params the structure to initialize */ void cmdline_parser_params_init(struct cmdline_parser_params *params); /** * Allocates dynamically a cmdline_parser_params structure and initializes * all its fields to their default values * @return the created and initialized cmdline_parser_params structure */ struct cmdline_parser_params *cmdline_parser_params_create(void); /** * Initializes the passed gengetopt_args_info structure's fields * (also set default values for options that have a default) * @param args_info the structure to initialize */ void cmdline_parser_init (struct gengetopt_args_info *args_info); /** * Deallocates the string fields of the gengetopt_args_info structure * (but does not deallocate the structure itself) * @param args_info the structure to deallocate */ void cmdline_parser_free (struct gengetopt_args_info *args_info); /** * Checks that all the required options were specified * @param args_info the structure to check * @param prog_name the name of the program that will be used to print * possible errors * @return */ int cmdline_parser_required (struct gengetopt_args_info *args_info, const char *prog_name); extern char *cmdline_parser_enum_opt_values[] ; /**< @brief Possible values for enum-opt. */ #ifdef __cplusplus } #endif /* __cplusplus */ #endif /* CMDLINE1_H */The
<option>_givenfield is set to 1 when an argument for<option>has been specified (otherwise it is 0)21. This fields also counts the times a multiple option is specified (see Multiple Options). If the option accepts an argument and it is not offlagtype The<option>_argfield is set to the value passed at the command line. The<option>_argfield has the corresponding C type specified in the file passed to gengetopt.Notice that if an option has a default value, then the corresponding
<option>_argwill be initialized with that value but the corresponding<option>_givenwill NOT be initialized to 1. Thus,<option>_givenwill effectively inform you if the user has specified that command line option.The additional field
<option>_origis 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 conversions, 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>_argfield will contain a value taken from the specified list, while<option>_origcontains the (non-ambiguous) prefix specified at the command line.The user can always access this original value by using
<option>_originstead of<option>_arg, as he sees fit22. For instance, gengetopt itself uses the original value when it saves the command line options into a file (see the_file_savefunction in the following). However, apart from very specific command line processing, the user might hardly need the<option>_origfield, and can be always safely use<option>_arg.The
<option>_helpcontains the string (concerning this very option) that is printed when--helpcommand line is given.If it is of
flagtype, only the field<option>_flagis generated.The strings
cmdline_parser_purposeandcmdline_parser_usagecontain thepurposeas specified in the input file and the generated “usage” string as printed when--helpcommand line is given. Finally, the string arraycmdline_parser_helpcontains the strings (one for each option) printed when--helpcommand line is given (this array is terminated by a null string element). If hidden options are used also thecmdline_parser_full_helparray is available (containing also help strings concerning hidden options). If at least one option hasdetails, then thecmdline_parser_detailed_helparray is available (containing also help strings concerning hidden options and details for options). All these strings can be used by the programmer to build a customized help output23.Even if
<option>_givenis 0, the corresponding<option>_argis set to default value (if one has been specified for<option>). However, in this case, the<option>_origis set toNULL.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_longis 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_freecan be called to deallocate memory allocated by the parser for string and multiple options.
cmdline_parser_initcan be called to initialize the struct (it is not mandatory, since it is done automatically by the command line parser).
cmdline_parser_file_save24 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. Alternatively, you can usecmdline_parser_dump25 that takes as the first parameter an already open stream (FILE *) instead of a file name.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
sample1executable:gcc -c cmdline1.c g++ -c main1.cc g++ -o sample1 cmdline1.o main1.o(Here we assume that
getopt_longis 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
--helpof the parser generated from sample1.ggo by specifying the following options to gengetopt:--long-help -u --show-required(see Invoking gengetopt for further explanation for these command line options).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 2.0 Usage: sample1 -iINT|--int-opt=INT [-h|--help] [--detailed-help] [--full-help] [-V|--version] [-sfilename|--str-opt=filename] [-mINT|--my-opt=INT] [--flag-opt] [-F|--funct-opt] [--long-opt=LONG] [--def-opt=STRING] [--enum-opt=STRING] [-DINT|--dependant=INT] [FILES]... -h, --help Print help and exit --detailed-help Print help, including all details and hidden options, 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 (mandatory) 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
filenameis printed instead ofSTRINGfor the option--str-opt(sincetypestrwas used in the sample1.ggo file) and how the description of--my-optis wrapped to 80 columns, and how the\nis actually interpreted as a newline request. Also the usage string is wrapped. Moreover, since-S,--secretis an hidden option (See Hidden options.) it is not printed; if you wanted that to be printed, you should use--full-help. The option--func-opthas also thedetails, but they are not printed with--help.Finally, notice how the
textstrings are printed in the help output (and the empty line after the “more involved options” section achieved with an emptytextstring).Instead, here is the output of
--detailed-helpof the parser generated from sample1.ggo. You may want to compare this output with the one produced by--help(See Output of--help.); in particular, you may notice that the hidden option--secretis actually printed and the details of--func-optare printed too: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 2.0 Usage: sample1 -iINT|--int-opt=INT [-h|--help] [--detailed-help] [--full-help] [-V|--version] [-sfilename|--str-opt=filename] [-mINT|--my-opt=INT] [--flag-opt] [-F|--funct-opt] [--long-opt=LONG] [--def-opt=STRING] [--enum-opt=STRING] [-DINT|--dependant=INT] [FILES]... -h, --help Print help and exit --detailed-help Print help, including all details and hidden options, 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 (mandatory) more involved options: the following options are more complex --flag-opt A flag option (default=off) -F, --funct-opt A function option A function option is basically an option with no argument. It can be used, e.g., to specify a specific behavior for a program. Well, this further explanation is quite useless, but it's only to show an example of an option with details, which will be printed only when --detailed-help is given at the command line. 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') -S, --secret=INT hidden option will not appear in --help -D, --dependant=INT option that depends on str-opt An ending text.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.