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POPT(3)			   Linux Programmer's Manual		       POPT(3)

NAME
       popt - Parse command line options

SYNOPSIS
       #include	<popt.h>

       poptContext poptGetContext(const	char * name, int argc,
				  const	char **	argv,
				  const	struct poptOption * options,
				  int flags);

       void poptFreeContext(poptContext	con);

       void poptResetContext(poptContext con);

       int poptGetNextOpt(poptContext con);

       const char * poptGetOptArg(poptContext con);

       const char * poptGetArg(poptContext con);

       const char * poptPeekArg(poptContext con);

       const char ** poptGetArgs(poptContext con);

       const char * poptStrerror(const int error);

       const char * poptBadOption(poptContext con, int flags);

       int poptReadDefaultConfig(poptContext con, int flags);

       int poptReadConfigFile(poptContext con, char * fn);

       int poptAddAlias(poptContext con, struct	poptAlias alias,
			int flags);

       int poptParseArgvString(char * s, int *	argcPtr,
			       const char *** argvPtr);

       int poptDupArgv(int argc, const char ** argv, int * argcPtr,
			       const char *** argvPtr);

       int poptStuffArgs(poptContext con, const	char **	argv);

DESCRIPTION
       The  popt  library exists essentially for parsing command-line options.
       It is found superior in many ways when compared to parsing the argv ar-
       ray  by	hand  or using the getopt functions getopt() and getopt_long()
       [see getopt(3)].	 Some specific advantages of popt  are:	 it  does  not
       utilize global variables, thus enabling multiple	passes in parsing argv
       ; it can	parse an arbitrary  array  of  argv-style  elements,  allowing
       parsing of command-line-strings from any	source;	it provides a standard
       method of option	aliasing (to be	discussed at length  below.);  it  can
       exec external option filters; and, finally, it can automatically	gener-
       ate help	and usage messages for the application.

       Like getopt_long(), the popt library supports short and long style  op-
       tions.	Recall	that a short option consists of	a - character followed
       by a single alphanumeric	character.  A long option, common in GNU util-
       ities,  consists	 of  two  - characters followed	by a string made up of
       letters,	numbers	and hyphens.  Long options are optionally  allowed  to
       begin  with  a  single -, primarily to allow command-line compatibility
       between popt applications and X toolkit applications.  Either  type  of
       option  may  be followed	by an argument.	 A space separates a short op-
       tion from its arguments;	either a space or an = separates a long	option
       from an argument.

       The  popt library is highly portable and	should work on any POSIX plat-
       form.  The latest version is distributed	with rpm and is	always	avail-
       able from: ftp://ftp.rpm.org/pub/rpm/dist.

       It  may	be  redistributed under	the X consortium license, see the file
       COPYING in the popt source distribution for details.

BASIC POPT USAGE
   1. THE OPTION TABLE
       Applications provide popt with information on  their  command-line  op-
       tions  by  means	of an "option table," i.e., an array of	struct poptOp-
       tion structures:

       #include	<popt.h>

       struct poptOption {
	   const char *	longName; /* may be NULL */
	   char	shortName;	  /* may be '\0' */
	   int argInfo;
	   void	* arg;		  /* depends on	argInfo	*/
	   int val;		  /* 0 means don't return, just	update flag */
	   char	* descrip;	  /* description for autohelp -- may be	NULL */
	   char	* argDescrip;	  /* argument description for autohelp */
       };

       Each member of the table	defines	a single option	that may be passed  to
       the  program.   Long  and  short	options	are considered a single	option
       that may	occur in two different forms.  The first two members, longName
       and  shortName,	define	the  names  of the option; the first is	a long
       name, while the latter is a single character.

       The argInfo member tells	popt what type of argument is  expected	 after
       the  option.  If	no argument is expected, POPT_ARG_NONE should be used.
       The rest	of the valid values are	shown in the following table:

       Value		   Description			      arg Type
       POPT_ARG_NONE	   No argument expected		      int
       POPT_ARG_STRING	   No type checking to be performed   char *
       POPT_ARG_ARGV	   No type checking to be performed   char **
       POPT_ARG_SHORT	   An short argument is	expected      short
       POPT_ARG_INT	   An integer argument is expected    int
       POPT_ARG_LONG	   A long integer is expected	      long
       POPT_ARG_LONGLONG   A long long integer is expected    long long
       POPT_ARG_VAL	   Integer value taken from val	      int
       POPT_ARG_FLOAT	   An float argument is	expected      float
       POPT_ARG_DOUBLE	   A double argument is	expected      double

       For numeric values, if the argInfo value	is bitwise or'd	 with  one  of
       POPT_ARGFLAG_OR,	 POPT_ARGFLAG_AND,  or	POPT_ARGFLAG_XOR, the value is
       saved by	performing an OR, AND, or XOR.	If the argInfo value  is  bit-
       wise  or'd with POPT_ARGFLAG_NOT, the value will	be negated before sav-
       ing. For	 the  common  operations  of  setting  and/or  clearing	 bits,
       POPT_BIT_SET and	POPT_BIT_CLR have the appropriate flags	set to perform
       bit operations.

       If the argInfo value is bitwise	or'd  with  POPT_ARGFLAG_ONEDASH,  the
       long argument may be given with a single	- instead of two. For example,
       if --longopt is an  option  with	 POPT_ARGFLAG_ONEDASH,	is  specified,
       -longopt	is accepted as well.

       The  next  element,  arg,  allows  popt to automatically	update program
       variables when the option is used. If arg is NULL, it  is  ignored  and
       popt  takes no special action.  Otherwise it should point to a variable
       of the type indicated in	the right-most column of the  table  above.  A
       POPT_ARG_ARGV  arg  will	(re-)allocate an array of char * string	point-
       ers, append the string argument,	and add	a NULL sentinel	at the end  of
       the array as needed.  The target	char **	address	of a POPT_ARG_ARGV arg
       should be initialized to	NULL.

       If the option takes no argument (argInfo	is POPT_ARG_NONE),  the	 vari-
       able  pointed to	by arg is set to 1 when	the option is used.  (Inciden-
       tally, it will perhaps not escape the attention of  hunt-and-peck  typ-
       ists that the value of POPT_ARG_NONE is 0.)  If the option does take an
       argument, the variable that arg points to is  updated  to  reflect  the
       value  of  the  argument.  Any string is	acceptable for POPT_ARG_STRING
       and  POPT_ARG_ARGV   arguments,	 but   POPT_ARG_INT,   POPT_ARG_SHORT,
       POPT_ARG_LONG,  POPT_ARG_LONGLONG,  POPT_ARG_FLOAT, and POPT_ARG_DOUBLE
       are converted to	the appropriate	type, and an  error  returned  if  the
       conversion fails.

       POPT_ARG_VAL  causes  arg  to be	set to the (integer) value of val when
       the argument is found.  This is most often useful  for  mutually-exclu-
       sive arguments in cases where it	is not an error	for multiple arguments
       to occur	and where you want the last argument specified to win; for ex-
       ample, "rm -i -f".  POPT_ARG_VAL	causes the parsing function not	to re-
       turn a value, since the value of	val has	already	been used.

       If the argInfo value is bitwise or'd  with  POPT_ARGFLAG_OPTIONAL,  the
       argument	 to the	long option may	be omitted. If the long	option is used
       without an argument, a default value of zero or NULL will be saved  (if
       the  arg	pointer	is present), otherwise behavior	will be	identical to a
       long option with	argument.

       The next	option,	val, is	the value popt's parsing function  should  re-
       turn  when the option is	encountered.  If it is 0, the parsing function
       does not	return a value,	instead	parsing	the  next  command-line	 argu-
       ment.

       The last	two options, descrip and argDescrip are	only required if auto-
       matic help messages are desired (automatic usage	messages can be	gener-
       ated  without  them). descrip is	a text description of the argument and
       argdescrip is a short summary of	the type of arguments the  option  ex-
       pects, or NULL if the option doesn't require any	arguments.

       If  popt	should automatically provide --usage and --help	(-?)  options,
       one line	in the table should be the macro  POPT_AUTOHELP.   This	 macro
       includes	 another option	table (via POPT_ARG_INCLUDE_TABLE ; see	below)
       in the main one which provides the table	entries	for  these  arguments.
       When --usage or --help are passed to programs which use popt's automat-
       ical help, popt displays	the appropriate	message	on stderr as  soon  as
       it  finds the option, and exits the program with	a return code of 0. If
       you want	to use popt's automatic	help generation	in  a  different  way,
       you  need  to explicitly	add the	option entries to your programs	option
       table instead of	using POPT_AUTOHELP.

       If the argInfo value is bitwise or'd with POPT_ARGFLAG_DOC_HIDDEN,  the
       argument	will not be shown in help output.

       If  the	argInfo	 value is bitwise or'd with POPT_ARGFLAG_SHOW_DEFAULT,
       the inital value	of the arg will	be shown in help output.

       The final structure in the table	should have all	the pointer values set
       to  NULL	and all	the arithmetic values set to 0,	marking	the end	of the
       table. The macro	POPT_TABLEEND is provided to do	that.

       There are two types of option table entries which do not	 specify  com-
       mand  line options. When	either of these	types of entries are used, the
       longName	element	must be	NULL and the shortName element must be '\0'.

       The first of these special entry	types allows the application  to  nest
       another	option table in	the current one; such nesting may extend quite
       deeply (the actual depth	is limited by the program's stack).  Including
       other  option tables allows a library to	provide	a standard set of com-
       mand-line options to every program which	uses it	(this is often done in
       graphical  programming  toolkits,  for  example).  To  do this, set the
       argInfo field to	POPT_ARG_INCLUDE_TABLE and the arg field to  point  to
       the  table which	is being included. If automatic	help generation	is be-
       ing used, the descrip field should contain a overall description	of the
       option table being included.

       The other special option	table entry type tells popt to call a function
       (a callback) when any option in that table is found. This is especially
       usefull	when  included	option	tables	are being used,	as the program
       which provides the top-level option table doesn't need to be  aware  of
       the  other  options  which  are	provided by the	included table.	When a
       callback	is set for a table, the	parsing	function never returns	infor-
       mation  on an option in the table. Instead, options information must be
       retained	via the	callback or by having popt set a variable through  the
       option's	arg field.  Option callbacks should match the following	proto-
       type:

       void poptCallbackType(poptContext con,
			     const struct poptOption * opt,
			     const char	* arg, void * data);

       The first parameter is the context which	is being parsed	(see the  next
       section	for  information  on contexts),	opt points to the option which
       triggered this callback,	and arg	is the option's	argument.  If the  op-
       tion does not take an argument, arg is NULL.  The final parameter, data
       is taken	from the descrip field of the option table entry which defined
       the  callback.  As descrip is a pointer,	this allows callback functions
       to be passed an arbitrary set of	data (though a typecast	will  have  to
       be used).

       The  option  table  entry  which	 defines  a callback has an argInfo of
       POPT_ARG_CALLBACK, an arg which points to the callback function,	and  a
       descrip	field which specifies an arbitrary pointer to be passed	to the
       callback.

   2. CREATING A CONTEXT
       popt can	interleave the parsing of multiple command-line	sets.  It  al-
       lows  this by keeping all the state information for a particular	set of
       command-line arguments in a poptContext data structure, an opaque  type
       that should not be modified outside the popt library.

       New popt	contexts are created by	poptGetContext():

       poptContext poptGetContext(const	char * name, int argc,
				  const	char **	argv,
				  const	struct poptOption * options,
				  int flags);

       The  first  parameter, name, is used only for alias handling (discussed
       later). It should be the	name of	the application	whose options are  be-
       ing  parsed,  or	 should	 be NULL if no option aliasing is desired. The
       next two	arguments specify the command-line arguments to	 parse.	 These
       are generally passed to poptGetContext()	exactly	as they	were passed to
       the program's main() function. The options parameter points to the  ta-
       ble  of	command-line options, which was	described in the previous sec-
       tion. The final parameter, flags, can take one of three values:

       Value			    Description
       POPT_CONTEXT_NO_EXEC	    Ignore exec	expansions
       POPT_CONTEXT_KEEP_FIRST	    Do not ignore argv[0]
       POPT_CONTEXT_POSIXMEHARDER   Options cannot follow arguments

       A poptContext keeps track of which options have already been parsed and
       which remain, among other things. If a program wishes to	restart	option
       processing of a set of arguments, it can	reset the poptContext by pass-
       ing the context as the sole argument to poptResetContext().

       When argument processing	is complete, the process should	free the popt-
       Context as it contains  dynamically  allocated  components.  The	 popt-
       FreeContext()  function	takes  a  poptContext as its sole argument and
       frees the resources the context is using.

       Here are	the prototypes of  both	 poptResetContext()  and  poptFreeCon-
       text():

       #include	<popt.h>
       void poptFreeContext(poptContext	con);
       void poptResetContext(poptContext con);

   3. PARSING THE COMMAND LINE
       After  an  application  has created a poptContext, it may begin parsing
       arguments. poptGetNextOpt() performs the	actual argument	parsing.

       #include	<popt.h>
       int poptGetNextOpt(poptContext con);

       Taking the context as its sole argument,	this function parses the  next
       command-line argument found. After finding the next argument in the op-
       tion table, the function	fills in the object pointed to by  the	option
       table  entry's  arg pointer if it is not	NULL. If the val entry for the
       option is non-0,	the function then returns that value. Otherwise, popt-
       GetNextOpt() continues on to the	next argument.

       poptGetNextOpt()	 returns  -1  when the final argument has been parsed,
       and other negative values when errors occur. This makes it a good  idea
       to keep the val elements	in the options table greater than 0.

       If  all	of  the	command-line options are handled through arg pointers,
       command-line parsing is reduced to the following	line of	code:

       rc = poptGetNextOpt(poptcon);

       Many applications require more complex command-line parsing than	 this,
       however,	and use	the following structure:

       while ((rc = poptGetNextOpt(poptcon)) > 0) {
	    switch (rc)	{
		 /* specific arguments are handled here	*/
	    }
       }

       When  returned  options	are handled, the application needs to know the
       value of	any arguments that were	specified after	the option. There  are
       two  ways  to  discover	them. One is to	ask popt to fill in a variable
       with the	value of the option through the	option table's	arg  elements.
       The other is to use poptGetOptArg():

       #include	<popt.h>
       char * poptGetOptArg(poptContext	con);

       This  function returns the argument given for the final option returned
       by poptGetNextOpt(), or it returns NULL if no argument  was  specified.
       The calling function is responsible for deallocating this string.

   4. LEFTOVER ARGUMENTS
       Many  applications  take	an arbitrary number of command-line arguments,
       such as a list of file names. When popt	encounters  an	argument  that
       does  not begin with a -, it assumes it is such an argument and adds it
       to a list of leftover arguments.	Three functions	allow applications  to
       access such arguments:

       const char * poptGetArg(poptContext con);
	      This function returns the	next leftover argument and marks it as
	      processed.

       const char * poptPeekArg(poptContext con);
	      The next leftover	argument is returned but not  marked  as  pro-
	      cessed.  This allows an application to look ahead	into the argu-
	      ment list, without modifying the list.

       const char ** poptGetArgs(poptContext con);
	      All the leftover arguments are returned in a manner identical to
	      argv.   The  final element in the	returned array points to NULL,
	      indicating the end of the	arguments.

   5. AUTOMATIC	HELP MESSAGES
       The popt	library	can automatically generate  help  messages  which  de-
       scribe  the options a program accepts. There are	two types of help mes-
       sages which can be generated. Usage messages are	a short	messages which
       lists valid options, but	does not describe them.	Help messages describe
       each option on one (or more) lines, resulting in	 a  longer,  but  more
       useful, message.	Whenever automatic help	messages are used, the descrip
       and argDescrip fields struct poptOption members should be filled	in for
       each option.

       The  POPT_AUTOHELP  macro  makes	it easy	to add --usage and --help mes-
       sages to	your program, and is described in part 1 of this man page.  If
       more control is needed over your	help messages, the following two func-
       tions are available:

       #include	<popt.h>
       void poptPrintHelp(poptContext con, FILE	* f, int flags);
       void poptPrintUsage(poptContext con, FILE * f, int flags);

       poptPrintHelp() displays	the standard help message to  the  stdio  file
       descriptor  f,  while  poptPrintUsage() displays	the shorter usage mes-
       sage. Both functions currently ignore the flags argument; it  is	 there
       to allow	future changes.

ERROR HANDLING
       All of the popt functions that can return errors	return integers.  When
       an error	occurs,	a negative error code is returned. The following table
       summarizes the error codes that occur:

	    Error		       Description
       POPT_ERROR_NOARG	      Argument missing for an option.
       POPT_ERROR_BADOPT      Option's argument	couldn't be parsed.
       POPT_ERROR_OPTSTOODEEP Option aliasing nested too deeply.
       POPT_ERROR_BADQUOTE    Quotations do not	match.
       POPT_ERROR_BADNUMBER   Option couldn't be converted to number.
       POPT_ERROR_OVERFLOW    A	given number was too big or small.

       Here is a more detailed discussion of each error:

       POPT_ERROR_NOARG
	      An option	that requires an argument was specified	on the command
	      line, but	no argument was	given. This can	be  returned  only  by
	      poptGetNextOpt().

       POPT_ERROR_BADOPT
	      An  option was specified in argv but is not in the option	table.
	      This error can be	returned only from poptGetNextOpt().

       POPT_ERROR_OPTSTOODEEP
	      A	set of option aliases is nested	too  deeply.  Currently,  popt
	      follows  options	only  10 levels	to prevent infinite recursion.
	      Only poptGetNextOpt() can	return this error.

       POPT_ERROR_BADQUOTE
	      A	parsed string has a quotation mismatch (such as	a single  quo-
	      tation  mark).  poptParseArgvString(),  poptReadConfigFile(), or
	      poptReadDefaultConfig() can return this error.

       POPT_ERROR_BADNUMBER
	      A	conversion from	a string to a number (int or long) failed  due
	      to the string containing nonnumeric characters. This occurs when
	      poptGetNextOpt() is processing an	argument of type POPT_ARG_INT,
	      POPT_ARG_SHORT,	      POPT_ARG_LONG,	    POPT_ARG_LONGLONG,
	      POPT_ARG_FLOAT, or POPT_ARG_DOUBLE.

       POPT_ERROR_OVERFLOW
	      A	string-to-number conversion failed because the number was  too
	      large  or	 too  small. Like POPT_ERROR_BADNUMBER,	this error can
	      occur only when poptGetNextOpt() is processing  an  argument  of
	      type POPT_ARG_INT, POPT_ARG_SHORT, POPT_ARG_LONG,	POPT_ARG_LONG-
	      LONG, POPT_ARG_FLOAT, or POPT_ARG_DOUBLE.

       POPT_ERROR_ERRNO
	      A	system call returned with an error, and	errno  still  contains
	      the  error  from	the system call. Both poptReadConfigFile() and
	      poptReadDefaultConfig() can return this error.

       Two functions are available to make it easy for applications to provide
       good error messages.

	      const char * poptStrerror(const int error);
	      This  function  takes a popt error code and returns a string de-
	      scribing the error, just as with the standard  strerror()	 func-
	      tion.

	      const char * poptBadOption(poptContext con, int flags);
	      If  an error occurred during poptGetNextOpt(), this function re-
	      turns the	option that caused the error. If the flags argument is
	      set to POPT_BADOPTION_NOALIAS, the outermost option is returned.
	      Otherwise, flags should be 0, and	the option  that  is  returned
	      may have been specified through an alias.

       These  two functions make popt error handling trivial for most applica-
       tions. When an error is detected	from most of the functions,  an	 error
       message	is  printed  along  with the error string from poptStrerror().
       When an error occurs during argument parsing, code similiar to the fol-
       lowing displays a useful	error message:

       fprintf(stderr, "%s: %s\n",
	       poptBadOption(optCon, POPT_BADOPTION_NOALIAS),
	       poptStrerror(rc));

OPTION ALIASING
       One  of the primary benefits of using popt over getopt()	is the ability
       to use option aliasing. This lets the user specify  options  that  popt
       expands	into  other  options  when they	are specified. If the standard
       grep program made use of	popt, users could add a	--text option that ex-
       panded  to -i -n	-E -2 to let them more easily find information in text
       files.

   1. SPECIFYING ALIASES
       Aliases are normally specified in two places: /etc/popt and  the	 .popt
       file  in	 the user's home directory (found through the HOME environment
       variable). Both files have the same  format,  an	 arbitrary  number  of
       lines formatted like this:

       appname alias newoption expansion

       The  appname  is	the name of the	application, which must	be the same as
       the name	parameter passed to poptGetContext(). This allows each file to
       specify aliases for multiple programs. The alias	keyword	specifies that
       an alias	is being defined; currently popt configuration	files  support
       only  aliases, but other	abilities may be added in the future. The next
       option is the option that should	be aliased, and	it  may	 be  either  a
       short  or  a  long option. The rest of the line specifies the expansion
       for the alias. It is parsed similarly to	a shell	command, which	allows
       \, ", and ' to be used for quoting. If a	backslash is the final charac-
       ter on a	line, the next line in the file	is assumed  to	be  a  logical
       continuation of the line	containing the backslash, just as in shell.

       The  following  entry would add a --text	option to the grep command, as
       suggested at the	beginning of this section.

       grep alias --text -i -n -E -2

   2. ENABLING ALIASES
       An application must enable alias	expansion  for	a  poptContext	before
       calling	poptGetNextArg() for the first time. There are three functions
       that define aliases for a context:

	      int poptReadDefaultConfig(poptContext con, int flags);
	      This function reads aliases from /etc/popt and the .popt file in
	      the  user's  home	directory. Currently, flags should be NULL, as
	      it is provided only for future expansion.

	      int poptReadConfigFile(poptContext con, char * fn);
	      The file specified by fn is opened and parsed as a popt configu-
	      ration  file.  This allows programs to use program-specific con-
	      figuration files.

	      int poptAddAlias(poptContext con,	struct poptAlias alias,
			       int flags);
	      Occasionally, processes want to specify aliases  without	having
	      to read them from	a configuration	file. This function adds a new
	      alias to a context. The flags argument should be	0,  as	it  is
	      currently	reserved for future expansion. The new alias is	speci-
	      fied as a	struct poptAlias, which	is defined as:

	      struct poptAlias {
		   const char *	longName; /* may be NULL */
		   char	shortName; /* may be '\0' */
		   int argc;
		   const char ** argv; /* must be free()able */
	      };

	      The first	two elements, longName and shortName, specify the  op-
	      tion  that  is aliased. The final	two, argc and argv, define the
	      expansion	to use when the	aliases	option is encountered.

PARSING	ARGUMENT STRINGS
       Although	popt is	usually	used for  parsing  arguments  already  divided
       into  an	argv-style array, some programs	need to	parse strings that are
       formatted identically to	command	lines. To facilitate this,  popt  pro-
       vides  a	 function that parses a	string into an array of	strings, using
       rules similiar to normal	shell parsing.

       #include	<popt.h>
       int poptParseArgvString(char * s, int * argcPtr,
			       char ***	argvPtr);
       int poptDupArgv(int argc, const char ** argv, int * argcPtr,
			       const char *** argvPtr);

       The string s is parsed into an argv-style array.	The integer pointed to
       by  the	argcPtr	 parameter contains the	number of elements parsed, and
       the final argvPtr parameter contains the	address	of the	newly  created
       array.	The routine poptDupArgv() can be used to make a	copy of	an ex-
       isting argument array.

       The argvPtr created by poptParseArgvString() or poptDupArgv() is	 suit-
       able to pass directly to	poptGetContext().  Both	routines return	a sin-
       gle dynamically allocated contiguous block of  storage  and  should  be
       free()ed	when the application is	finished with the storage.

HANDLING EXTRA ARGUMENTS
       Some  applications implement the	equivalent of option aliasing but need
       to do so	through	special	logic. The poptStuffArgs() function allows  an
       application to insert new arguments into	the current poptContext.

       #include	<popt.h>
       int poptStuffArgs(poptContext con, const	char **	argv);

       The  passed  argv  must	have a NULL pointer as its final element. When
       poptGetNextOpt()	is next	called,	the "stuffed" arguments	are the	 first
       to be parsed. popt returns to the normal	arguments once all the stuffed
       arguments have been exhausted.

EXAMPLE
       The following example is	a simplified version of	 the  program  "robin"
       which  appears  in  Chapter 15 of the text cited	below.	Robin has been
       stripped	of everything but its  argument-parsing	 logic,	 slightly  re-
       worked,	and  renamed  "parse."	It may prove useful in illustrating at
       least some of the features of the extremely rich	popt library.

       #include	<popt.h>
       #include	<stdio.h>

       void usage(poptContext optCon, int exitcode, char *error, char *addl) {
	   poptPrintUsage(optCon, stderr, 0);
	   if (error) fprintf(stderr, "%s: %s0,	error, addl);
	   exit(exitcode);
       }

       int main(int argc, char *argv[])	{
	  char	  c;		/* used	for argument parsing */
	  int	  i = 0;	/* used	for tracking options */
	  char	  *portname;
	  int	  speed	= 0;	/* used	in argument parsing to set speed */
	  int	  raw =	0;	/* raw mode? */
	  int	  j;
	  char	  buf[BUFSIZ+1];
	  poptContext optCon;	/* context for parsing command-line options */

	  struct poptOption optionsTable[] = {
	     { "bps", 'b', POPT_ARG_INT, &speed, 0,
				 "signaling rate in bits-per-second", "BPS" },
	     { "crnl", 'c', 0, 0, 'c',
				 "expand cr characters to cr/lf	sequences", NULL },
	     { "hwflow", 'h', 0, 0, 'h',
				 "use hardware (RTS/CTS) flow control",	NULL },
	     { "noflow", 'n', 0, 0, 'n',
				 "use no flow control",	NULL },
	     { "raw", 'r', 0, &raw, 0,
				 "don't	perform	any character conversions", NULL },
	     { "swflow", 's', 0, 0, 's',
				 "use software (XON/XOF) flow control",	NULL } ,
	     POPT_AUTOHELP
	     { NULL, 0,	0, NULL, 0 }
	   };

	  optCon = poptGetContext(NULL,	argc, argv, optionsTable, 0);
	  poptSetOtherOptionHelp(optCon, "[OPTIONS]* <port>");

	  if (argc < 2)	{
				 poptPrintUsage(optCon,	stderr,	0);
				 exit(1);
	  }

	  /* Now do options processing,	get portname */
	  while	((c = poptGetNextOpt(optCon)) >= 0) {
	     switch (c)	{
	      case 'c':
		 buf[i++] = 'c';
		 break;
	      case 'h':
		 buf[i++] = 'h';
		 break;
	      case 's':
		 buf[i++] = 's';
		 break;
	      case 'n':
		 buf[i++] = 'n';
		 break;
	     }
	  }
	  portname = poptGetArg(optCon);
	  if((portname == NULL)	|| !(poptPeekArg(optCon) == NULL))
	     usage(optCon, 1, "Specify a single	port", ".e.g., /dev/cua0");

	  if (c	< -1) {
	     /*	an error occurred during option	processing */
	     fprintf(stderr, "%s: %s\n",
		     poptBadOption(optCon, POPT_BADOPTION_NOALIAS),
		     poptStrerror(c));
	     return 1;
	  }

	  /* Print out options,	portname chosen	*/
	  printf("Options  chosen: ");
	  for(j	= 0; j < i ; j++)
	     printf("-%c ", buf[j]);
	  if(raw) printf("-r ");
	  if(speed) printf("-b %d ", speed);
	  printf("\nPortname chosen: %s\n", portname);

	  poptFreeContext(optCon);
	  exit(0);
       }

       RPM, a popular Linux package management program,	 makes	heavy  use  of
       popt's  features.  Many	of  its	command-line arguments are implemented
       through popt aliases, which makes RPM an	excellent example  of  how  to
       take  advantage	of  the	popt library. For more information on RPM, see
       http://www.rpm.org. The popt source  code  distribution	includes  test
       program(s) which	use all	of the features	of the popt libraries in vari-
       ous ways. If a feature isn't working for	you, the popt test code	is the
       first place to look.

BUGS
       None presently known.

AUTHOR
       Erik W. Troan <ewt@redhat.com>

       This  man page is derived in part from Linux Application	Development by
       Michael K. Johnson and Erik W. Troan, Copyright	(c)  1998  by  Addison
       Wesley  Longman,	 Inc., and included in the popt	documentation with the
       permission of the Publisher and the appreciation	of the Authors.

       Thanks to Robert	Lynch for his extensive	work on	this man page.

SEE ALSO
       getopt(3)

       Linux Application Development, by Michael K. Johnson and	Erik W.	 Troan
       (Addison-Wesley,	1998; ISBN 0-201-30821-5), Chapter 24.

       popt.ps is a Postscript version of the above cited book chapter.	It can
       be   found   in	 the   source	archive	  for	popt   available   at:
       ftp://ftp.rpm.org/pub/rpm.

				 June 30, 1998			       POPT(3)

NAME | SYNOPSIS | DESCRIPTION | BASIC POPT USAGE | ERROR HANDLING | OPTION ALIASING | PARSING ARGUMENT STRINGS | HANDLING EXTRA ARGUMENTS | EXAMPLE | BUGS | AUTHOR | SEE ALSO

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