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1.1 root 1: .\" Copyright (c) 1988 Regents of the University of California.
2: .\" All rights reserved.
3: .\"
4: .\" Redistribution and use in source and binary forms are permitted provided
5: .\" that: (1) source distributions retain this entire copyright notice and
6: .\" comment, and (2) distributions including binaries display the following
7: .\" acknowledgement: ``This product includes software developed by the
8: .\" University of California, Berkeley and its contributors'' in the
9: .\" documentation or other materials provided with the distribution and in
10: .\" all advertising materials mentioning features or use of this software.
11: .\" Neither the name of the University nor the names of its contributors may
12: .\" be used to endorse or promote products derived from this software without
13: .\" specific prior written permission.
14: .\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
15: .\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
16: .\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
17: .\"
18: .\" @(#)getopt.3 6.15 (Berkeley) 6/23/90
19: .\"
20: .TH GETOPT 3 "June 23, 1990"
21: .UC 6
22: .SH NAME
23: getopt \- get option letter from argv
24: .SH SYNOPSIS
25: .ft B
26: .nf
27: int getopt(argc, argv, optstring)
28: int argc;
29: char **argv;
30: char *optstring;
31: .sp
32: extern char *optarg;
33: extern int optind;
34: extern int opterr;
35: .ft
36: .SH DESCRIPTION
37: .I Getopt
38: returns the next option letter in
39: .I argv
40: that matches a letter in
41: .IR optstring .
42: .I Optstring
43: is a string of recognized option letters; if a letter is followed by a
44: colon, the option is expected to have an argument that may or may not
45: be separated from it by white space.
46: .PP
47: On return from
48: .IR getopt ,
49: optarg is set to point to the start of any option argument.
50: .I Optind
51: contains the
52: .I argv
53: index of the next argument to be processed.
54: .PP
55: .I Opterr
56: and
57: .I optind
58: are both initialized to 1.
59: In order to use
60: .I getopt
61: to evaluate multiple sets of arguments, or to evaluate a single set of
62: arguments multiple times,
63: .I optind
64: must be initialized to the number of argv entries to be skipped in each
65: evaluation.
66: .PP
67: When all options have been processed (i.e., up to the first non-option
68: argument),
69: .I getopt
70: returns EOF.
71: The special option ``\-\-'' may be used to delimit the end of the options;
72: EOF will be returned, and the ``\-\-'' will be skipped.
73: .SH DIAGNOSTICS
74: .I Getopt
75: prints an error message on
76: .I stderr
77: and returns a question mark (``?'') when it encounters an option
78: letter not included in
79: .IR optstring ,
80: or it encounters an option that requires an argument which is not
81: supplied.
82: Setting
83: .I opterr
84: to a zero will disable these error messages.
85: .SH EXAMPLE
86: .nf
87: .in +5
88: extern char *optarg;
89: extern int optind;
90: int bflag, ch, fd;
91:
92: bflag = 0;
93: while ((ch = getopt(argc, argv, "bf:")) != EOF)
94: switch(ch) {
95: case 'b':
96: bflag = 1;
97: break;
98: case 'f':
99: if ((fd = open(optarg, O_RDONLY, 0)) < 0) {
100: (void)fprintf(stderr,
101: "myname: unable to read file %s.\en", optarg);
102: exit(1);
103: }
104: break;
105: case '?':
106: default:
107: usage();
108: }
109: argc -= optind;
110: argv += optind;
111: .fi
112: .SH BUGS
113: Option arguments are allowed to begin with ``\-''; this is reasonable but
114: reduces the amount of error checking possible.
115: .PP
116: A single dash (``-'') may be specified as an character in
117: .IR optstring ,
118: however it should
119: .B never
120: have an argument associated with it.
121: This allows
122: .I getopt
123: to be used with programs that expect ``-'' as an option flag.
124: This practice is wrong, and should not be used in any current development.
125: It is provided for backward compatibility
126: .BR only .
127: By default, a single dash causes
128: .I getopt
129: to return EOF.
130: This is, we believe, compatible with System V.
131: .PP
132: It is also possible to handle digits as option letters.
133: This allows
134: .I getopt
135: to be used with programs that expect a number (``-3'') as an option.
136: This practice is wrong, and should not be used in any current development.
137: It is provided for backward compatibility
138: .BR only .
139: The following code fragment works fairly well.
140: .sp
141: .nf
142: .in +5
143: int length;
144: char *p;
145:
146: while ((c = getopt(argc, argv, "0123456789")) != EOF)
147: switch (c) {
148: case '0': case '1': case '2': case '3': case '4':
149: case '5': case '6': case '7': case '8': case '9':
150: p = argv[optind - 1];
151: if (p[0] == '-' && p[1] == ch && !p[2])
152: length = atoi(++p);
153: else
154: length = atoi(argv[optind] + 1);
155: break;
156: }
157: }
158: .fi
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