getsubopt man page on Archlinux

Man page or keyword search:  
man Server   11224 pages
apropos Keyword Search (all sections)
Output format
Archlinux logo
[printable version]

GETSUBOPT(3P)		   POSIX Programmer's Manual		 GETSUBOPT(3P)

       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the	 corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.

       getsubopt — parse suboption arguments from a string

       #include <stdlib.h>

       int getsubopt(char **optionp, char * const *keylistp, char **valuep);

       The getsubopt() function shall parse  suboption	arguments  in  a  flag
       argument. Such options often result from the use of getopt().

       The  getsubopt()	 argument  optionp  is	a  pointer to a pointer to the
       option argument string. The suboption arguments shall be	 separated  by
       <comma>	characters and each may consist of either a single token, or a
       token-value pair separated by an <equals-sign>.

       The keylistp argument shall be a pointer to a vector  of	 strings.  The
       end  of	the  vector is identified by a null pointer. Each entry in the
       vector is one of the possible tokens that might be found	 in  *optionp.
       Since  <comma>  characters delimit suboption arguments in optionp, they
       should not appear in any of the strings pointed to by keylistp.	 Simi‐
       larly,  because	an <equals-sign> separates a token from its value, the
       application should not include an <equals-sign> in any of  the  strings
       pointed	to by keylistp.	 The getsubopt() function shall not modify the
       keylistp vector.

       The valuep argument is the address of a value string pointer.

       If a <comma> appears in optionp, it shall be interpreted as a suboption
       separator.  After  <comma> characters have been processed, if there are
       one or more <equals-sign> characters in a suboption string,  the	 first
       <equals-sign> in any suboption string shall be interpreted as a separa‐
       tor between a token and a value. Subsequent <equals-sign> characters in
       a suboption string shall be interpreted as part of the value.

       If the string at *optionp contains only one suboption argument (equiva‐
       lently, no <comma> characters), getsubopt() shall  update  *optionp  to
       point  to  the  null  character at the end of the string. Otherwise, it
       shall isolate the suboption argument by replacing the <comma> separator
       with  a null character, and shall update *optionp to point to the start
       of the next suboption argument. If the suboption argument has an	 asso‐
       ciated  value  (equivalently,  contains	an <equals-sign>), getsubopt()
       shall update *valuep to point to the value's first  character.	Other‐
       wise,  it  shall set *valuep to a null pointer. The calling application
       may use this information to determine whether the presence  or  absence
       of a value for the suboption is an error.

       Additionally,  when  getsubopt()	 fails to match the suboption argument
       with a token in the keylistp  array,  the  calling  application	should
       decide  if  this	 is  an error, or if the unrecognized option should be
       processed in another way.

       The getsubopt() function shall return the index of  the	matched	 token
       string, or −1 if no token strings were matched.

       No errors are defined.

       The following sections are informative.

   Parsing Suboptions
       The  following  example	uses the getsubopt() function to parse a value
       argument in  the	 optarg	 external  variable  returned  by  a  call  to

	   #include <stdio.h>
	   #include <stdlib.h>
	   #include <unistd.h>

	   int do_all;
	   const char *type;
	   int read_size;
	   int write_size;
	   int read_only;

	       RO_OPTION = 0,

	   const char *mount_opts[] =
	       [RO_OPTION] = "ro",
	       [RW_OPTION] = "rw",
	       [READ_SIZE_OPTION] = "rsize",
	       [WRITE_SIZE_OPTION] = "wsize",

	   main(int argc, char *argv[])
	       char *subopts, *value;
	       int opt;

	       while ((opt = getopt(argc, argv, "at:o:")) != -1)
		       case 'a':
			   do_all = 1;
		       case 't':
			   type = optarg;
		       case 'o':
			   subopts = optarg;
			   while (*subopts != ' ')
			       char *saved = subopts;
			       switch(getsubopt(&subopts, (char **)mount_opts,
			       case RO_OPTION:
				   read_only = 1;
			       case RW_OPTION:
				   read_only = 0;
			       case READ_SIZE_OPTION:
				   if (value == NULL)
				   read_size = atoi(value);
			       case WRITE_SIZE_OPTION:
				   if (value == NULL)
				   write_size = atoi(value);
				   /* Unknown suboption. */
				   printf("Unknown suboption `%s'\n", saved);

	       /* Do the real work. */

	       return 0;

       If the above example is invoked with:

	   program -o ro,rsize=512

       then  after option parsing, the variable do_all will be 0, type will be
       a null pointer, read_size will  be  512,	 write_size  will  be  0,  and
       read_only will be 1. If it is invoked with:

	   program -o oops

       it will print:

	   "Unknown suboption `oops'"

       before aborting.

       The  value  of *valuep when getsubopt() returns −1 is unspecified. His‐
       torical implementations	provide	 various  incompatible	extensions  to
       allow an application to access the suboption text that was not found in
       the keylistp array.

       The keylistp argument of getsubopt() is typed as	 char  *  const	 *  to
       match  historical  practice. However, the standard is clear that imple‐
       mentations will not modify either the array or the strings contained in
       the array, as if the argument had been typed const char * const *.



       The Base Definitions volume of POSIX.1‐2008, <stdlib.h>

       Portions	 of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
       --  Portable  Operating	System	Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
       cal  and	 Electronics  Engineers,  Inc  and  The	 Open Group.  (This is
       POSIX.1-2008 with the 2013 Technical Corrigendum	 1  applied.)  In  the
       event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard
       is  the	referee document. The original Standard can be obtained online
       at .

       Any typographical or formatting errors that appear  in  this  page  are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors,	 see  https://www.ker‐ .

IEEE/The Open Group		     2013			 GETSUBOPT(3P)

List of man pages available for Archlinux

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
Vote for polarhome
Free Shell Accounts :: the biggest list on the net