<TITLE>getopt</TITLE> <body background=/C_ref/GRAPHICS/bg1.gif> <hr> <pre> <h3>GETOPT(3) Linux Programmer's Manual GETOPT(3) </h3> <h3>NAME </h3> getopt - Read command line options <h3>SYNOPSIS </h3> #include <unistd.h> int getopt(int argc, char * const argv[], const char *optstring); extern char *optarg; extern int optind, opterr, optopt; #include <getopt.h> int getopt_long(int argc, char * const argv[], const char *shortopts, const struct option *longopts, int longind); <h3>DESCRIPTION </h3> The getopt() function parses the command line arguments. Its arguments argc and argv are the argument count and array as passed to the main() function on program invoca- tion. optstring is a list of available option characters. If such a character is followed by a colon, the option takes an argument, which is placed in optarg. The external variable optind is the index of the next array element of argv[] to be processed; it communicates from one call of getopt() to the next which element to process. The getopt_long() function works like getopt() except that it also accepts long options, started out by two dashes. If these take values, it is either in the form --arg=value or --arg value. It takes the additional arguments lon- gopts which is a pointer to the first element of an array of struct option declared in <getopt.h> as struct option { const char *name; int has_arg; int *flag; int val; }; The meaning of the different fields are: name is the name of the long option. has_arg is a boolean value which should be set to nonzero if the long option takes a value. flag determines the return value if getopt_long() <h3>GNU April 25, 1993 1 </h3> <h3>GETOPT(3) Linux Programmer's Manual GETOPT(3) </h3> returns a value for a long option; if it is non- zero, zero is returned as a function value, other- wise val. val determines the value to return if flag is zero. The last element of the array has to be filled with zeroes. The option_index points to the index of the long option relative to longopts. <h3>RETURN VALUE </h3> The getopt() function returns the option character if the option was found successfully, ':' if there was a missing parameter for one of the options, '?' for an unknown option character and -1 for the end of the option list. <h3>EXAMPLE </h3> The following example program, from the source code, illustrates the use of getopt_long() with most of its fea- tures. #include <stdio.h> int main (argc, argv) int argc; char **argv; { int c; int digit_optind = 0; while (1) { int this_option_optind = optind ? optind : 1; int option_index = 0; static struct option long_options[] = { {"add", 1, 0, 0}, {"append", 0, 0, 0}, {"delete", 1, 0, 0}, {"verbose", 0, 0, 0}, {"create", 1, 0, 'c'}, {"file", 1, 0, 0}, {0, 0, 0, 0} }; c = getopt_long (argc, argv, "abc:d:012", long_options, &option_index); if (c == -1) break; switch (c) <h3>GNU April 25, 1993 2 </h3> <h3>GETOPT(3) Linux Programmer's Manual GETOPT(3) </h3> { case 0: printf ("option %s", long_options[option_index].name); if (optarg) printf (" with arg %s", optarg); printf ("0); break; case '0': case '1': case '2': if (digit_optind != 0 && digit_optind != this_option_optind) printf ("digits occur in two different argv-elements.0); digit_optind = this_option_optind; printf ("option %c0, c); break; case 'a': printf ("option a0); break; case 'b': printf ("option b0); break; case 'c': printf ("option c with value `%s'0, optarg); break; case 'd': printf ("option d with value `%s'0, optarg); break; case '?': break; default: printf ("?? getopt returned character code 0%o ??0, c); } } if (optind < argc) { printf ("non-option ARGV-elements: "); while (optind < argc) printf ("%s ", argv[optind++]); printf ("0); } exit (0); } <h3>BUGS </h3> This manpage is confusing. <h3>GNU April 25, 1993 3 </h3> <h3>GETOPT(3) Linux Programmer's Manual GETOPT(3) </h3> <h3>CONFORMS TO </h3> getopt() : POSIX.1 <h3>GNU April 25, 1993 4 </h3> </pre> <P> <hr> <p> <center> <table border=2 width=80%> <tr align=center> <td width=25%> <a href=http:/C_ref/C/index.htm>Top</a> </td><td width=25%> <a href=http:/C_ref/C/master_index.html>Master Index</a> </td><td width=25%> <a href=http:/C_ref/C/SYNTAX/keywords.html>Keywords</a> </td><td width=25%> <a href=http:/C_ref/C/FUNCTIONS/function.ref.html>Functions</a> </td> </tr> </table> </center> <p> <hr> This manual page was brought to you by <i>mjl_man V-2.0</i>
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