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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
5: .\" provided that the above copyright notice and this paragraph are
6: .\" duplicated in all such forms and that any documentation,
7: .\" advertising materials, and other materials related to such
8: .\" distribution and use acknowledge that the software was developed
9: .\" by the University of California, Berkeley. The name of the
10: .\" University may not be used to endorse or promote products derived
11: .\" from this software without specific prior written permission.
12: .\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
13: .\" IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
14: .\" WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
15: .\"
16: .\" @(#)getopt.3 6.8 (Berkeley) 7/9/88
17: .\"
18: .TH GETOPT 3 "July 9, 1988"
19: .UC 6
20: .SH NAME
21: getopt \- get option letter from argv
22: .SH SYNOPSIS
23: .ft B
24: int getopt(argc, argv, optstring)
25: .br
26: int argc;
27: .br
28: char **argv;
29: .br
30: char *optstring;
31: .sp
32: extern char *optarg;
33: .br
34: extern int optind;
35: .br
36: extern int opterr;
37: .ft
38: .SH DESCRIPTION
39: .I Getopt
40: returns the next option letter in
41: .I argv
42: that matches a letter in
43: .IR optstring .
44: .I Optstring
45: is a string of recognized option letters;
46: if a letter is followed by a colon, the option is expected to have
47: an argument that may or may not be separated from it by white space.
48: .I Optarg
49: is set to point to the start of the option argument on return from
50: .IR getopt .
51: .PP
52: .I Getopt
53: places in
54: .I optind
55: the
56: .I argv
57: index of the next argument to be processed.
58: Because
59: .I optind
60: is external, it is normally initialized to zero automatically
61: before the first call to
62: .IR getopt .
63: .PP
64: When all options have been processed (i.e., up to the first
65: non-option argument),
66: .I getopt
67: returns
68: .BR EOF .
69: The special option
70: .B \-\-
71: may be used to delimit the end of the options;
72: .B EOF
73: will be returned, and
74: .B \-\-
75: will be skipped.
76: .SH DIAGNOSTICS
77: .I Getopt
78: prints an error message on
79: .I stderr
80: and returns a question mark
81: .RB ( ? )
82: when it encounters an option letter not included in
83: .IR optstring .
84: Setting \fIopterr\fP to a zero will disable this error message.
85: .SH EXAMPLE
86: The following code fragment shows how one might process the arguments
87: for a command that can take the mutually exclusive options
88: .B a
89: and
90: .BR b ,
91: and the options
92: .B f
93: and
94: .BR o ,
95: both of which require arguments:
96: .PP
97: .RS
98: .nf
99: main(argc, argv)
100: int argc;
101: char **argv;
102: {
103: int c;
104: extern int optind;
105: extern char *optarg;
106: \&.
107: \&.
108: \&.
109: while ((c = getopt(argc, argv, "abf:o:")) != EOF)
110: switch (c) {
111: case `a':
112: if (bflg)
113: errflg++;
114: else
115: aflg++;
116: break;
117: case `b':
118: if (aflg)
119: errflg++;
120: else
121: bproc();
122: break;
123: case `f':
124: ifile = optarg;
125: break;
126: case `o':
127: ofile = optarg;
128: break;
129: case `?':
130: default:
131: errflg++;
132: break;
133: }
134: if (errflg) {
135: fprintf(stderr, "Usage: ...");
136: exit(2);
137: }
138: for (; optind < argc; optind++) {
139: \&.
140: \&.
141: \&.
142: }
143: \&.
144: \&.
145: \&.
146: }
147: .RE
148: .SH HISTORY
149: Written by Henry Spencer, working from a Bell Labs manual page.
150: Modified by Keith Bostic to behave more like the System V version.
151: .SH BUGS
152: ``-'' may be specified as an option letter, however it should never have
153: an argument associated with it. This allows getopt to be used with
154: programs that think that ``-'' means standard input.
155: .PP
156: Option arguments are allowed to begin with ``\-'';
157: this is reasonable but reduces the amount of error checking possible.
158: .PP
159: .I Getopt
160: is quite flexible but the obvious price must be paid: there is much
161: it could do that it doesn't, like
162: checking mutually exclusive options, checking type of
163: option arguments, etc.
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