| 1 | .TH subgetopt 3 |
| 2 | .SH NAME |
| 3 | subgetopt \- get option character from command line |
| 4 | .SH SYNTAX |
| 5 | .B #include <subgetopt.h> |
| 6 | |
| 7 | char *\fBsgoptarg\fP; |
| 8 | .br |
| 9 | int \fBsgoptind\fP; |
| 10 | .br |
| 11 | int \fBsgoptpos\fP; |
| 12 | .br |
| 13 | int \fBsgoptdone\fP; |
| 14 | .br |
| 15 | int \fBsgoptproblem\fP; |
| 16 | |
| 17 | int \fBsgopt(\fP\fIargc,argv,opts\fR\fB)\fP; |
| 18 | |
| 19 | int \fIargc\fR; |
| 20 | .br |
| 21 | char **\fIargv\fR; |
| 22 | .br |
| 23 | char *\fIopts\fR; |
| 24 | .SH DESCRIPTION |
| 25 | .B sgopt |
| 26 | returns the next valid command-line option character |
| 27 | from |
| 28 | .IR argv . |
| 29 | |
| 30 | Valid option characters are listed in the |
| 31 | .I opts |
| 32 | string. |
| 33 | .I opts |
| 34 | may be empty. |
| 35 | A character in |
| 36 | .I opts |
| 37 | may be followed by a colon, |
| 38 | in which case it |
| 39 | takes an |
| 40 | .I option argument\fR. |
| 41 | Avoid using the characters ?, :, and \- as option characters. |
| 42 | |
| 43 | Below |
| 44 | .I option argument |
| 45 | is abbreviated |
| 46 | as |
| 47 | .I optarg |
| 48 | and |
| 49 | .I command-line argument |
| 50 | is abbreviated as |
| 51 | .IR cmdarg . |
| 52 | |
| 53 | Options are listed in cmdargs which begin with |
| 54 | a minus sign. |
| 55 | Several options which do not take optargs may be combined |
| 56 | into one cmdarg. |
| 57 | |
| 58 | An option which takes an optarg may be handled in two ways. |
| 59 | If it appears at the very end of a cmdarg, |
| 60 | then the entire next cmdarg is the optarg. |
| 61 | But if there are any characters in the cmdarg |
| 62 | after the option character, |
| 63 | then those characters form the optarg. |
| 64 | The optarg is returned in |
| 65 | .BR sgoptarg . |
| 66 | Next time |
| 67 | .B sgopt |
| 68 | looks at the cmdarg which follows the optarg. |
| 69 | |
| 70 | If a cmdarg does not begin with a hyphen, |
| 71 | or if it is a lone hyphen not followed by any characters, |
| 72 | or if it begins with two hyphens, |
| 73 | then it terminates option processing, |
| 74 | and |
| 75 | .B sgopt |
| 76 | returns an appropriate code. |
| 77 | If there are two hyphens, |
| 78 | .B sgopt |
| 79 | will advance attention to the next cmdarg, |
| 80 | so it can be called again to read further options. |
| 81 | .SH "PROPER USAGE" |
| 82 | .B sgoptproblem |
| 83 | should be used only when |
| 84 | .B sgopt |
| 85 | returns ?. |
| 86 | .B sgoptind |
| 87 | and |
| 88 | .B sgoptpos |
| 89 | are defined all the time. |
| 90 | .B sgoptarg |
| 91 | is defined all the time; |
| 92 | it is null unless |
| 93 | .B sgopt |
| 94 | has just returned an option with optarg. |
| 95 | |
| 96 | .B sgopt |
| 97 | is typically used as follows. |
| 98 | |
| 99 | .EX |
| 100 | #include <subgetopt.h> |
| 101 | |
| 102 | main(argc,argv) int argc; char **argv; { int opt; |
| 103 | |
| 104 | while ((opt = sgopt(argc,argv,"a:s")) != sgoptdone) |
| 105 | .br |
| 106 | switch(opt) { |
| 107 | .br |
| 108 | case 'a': |
| 109 | .br |
| 110 | printf("opt a with optarg %s\\n",sgoptarg); break; |
| 111 | .br |
| 112 | case 's': |
| 113 | .br |
| 114 | printf("opt s with no optarg\\n"); break; |
| 115 | .br |
| 116 | case '?': |
| 117 | .br |
| 118 | if (argv[sgoptind] && (sgoptind < argc)) |
| 119 | .br |
| 120 | printf("illegal opt %c\\n",sgoptproblem); |
| 121 | .br |
| 122 | else |
| 123 | .br |
| 124 | printf("missing arg, opt %c\\n",sgoptproblem); |
| 125 | .br |
| 126 | exit(1); |
| 127 | .br |
| 128 | } |
| 129 | |
| 130 | argv += sgoptind; |
| 131 | .br |
| 132 | while (*argv) printf("argument %s\\n",*argv++); |
| 133 | .br |
| 134 | exit(0); |
| 135 | .br |
| 136 | } |
| 137 | .EE |
| 138 | |
| 139 | The end of the command line is |
| 140 | marked by either |
| 141 | .IR argc , |
| 142 | or a null pointer in |
| 143 | .IR argv , |
| 144 | whichever comes first. |
| 145 | Normally |
| 146 | these two markers coincide, |
| 147 | so it is redundant |
| 148 | to test for |
| 149 | both |
| 150 | .I argv\fB[sgoptind] |
| 151 | and |
| 152 | .B sgoptind < \fIargc\fR. |
| 153 | The above code shows both tests as an illustration. |
| 154 | |
| 155 | .B Multiple option sets: |
| 156 | One useful technique is to call |
| 157 | .B sgopt |
| 158 | with a primary |
| 159 | .I opts |
| 160 | until it returns EOF, |
| 161 | then call |
| 162 | .B sgopt |
| 163 | with a secondary |
| 164 | .I opts |
| 165 | until it returns EOF. |
| 166 | The user can provide primary options, then a double hyphen, |
| 167 | and then secondary options. |
| 168 | No special handling is needed if some or all of the options are |
| 169 | omitted. |
| 170 | The same technique can be used for any number of option sets |
| 171 | in series. |
| 172 | |
| 173 | .B Multiple command lines: |
| 174 | Before parsing a new |
| 175 | .BR argv , |
| 176 | make sure to |
| 177 | set |
| 178 | .B sgoptind |
| 179 | and |
| 180 | .B sgoptpos |
| 181 | back to |
| 182 | 1 and 0. |
| 183 | .SH "PARSING STAGES" |
| 184 | .B sgopt |
| 185 | keeps track of its position in |
| 186 | .I argv |
| 187 | with |
| 188 | .B sgoptind |
| 189 | and |
| 190 | .BR sgoptpos , |
| 191 | which are initialized to 1 and 0. |
| 192 | It looks at |
| 193 | .I argv\fB[sgoptind][sgoptpos] |
| 194 | and following characters. |
| 195 | |
| 196 | .B sgopt |
| 197 | indicates |
| 198 | that no more options are available by |
| 199 | returning |
| 200 | .BR sgoptdone , |
| 201 | which is initialized to |
| 202 | .BR SUBGETOPTDONE , |
| 203 | which is defined as \-1. |
| 204 | |
| 205 | .B sgopt |
| 206 | begins by setting |
| 207 | .B optarg |
| 208 | to null. |
| 209 | |
| 210 | .B Ending conditions: |
| 211 | If |
| 212 | .I argv |
| 213 | is null, or |
| 214 | .B sgoptind |
| 215 | is larger than |
| 216 | .IR argc , |
| 217 | or the current cmdarg |
| 218 | .I argv\fB[sgoptind] |
| 219 | is null, |
| 220 | then |
| 221 | .B sgopt |
| 222 | returns |
| 223 | .BR optdone . |
| 224 | |
| 225 | .B Stage one: |
| 226 | If the current character |
| 227 | is zero, |
| 228 | .B sgopt |
| 229 | moves to the beginning of the next cmdarg. |
| 230 | It then checks the ending conditions again. |
| 231 | |
| 232 | .B Stage two: |
| 233 | If |
| 234 | the current position is the begining of the cmdarg, |
| 235 | .B sgopt |
| 236 | checks whether |
| 237 | the current character |
| 238 | is a minus sign. |
| 239 | If not it returns |
| 240 | .BR optdone . |
| 241 | It then |
| 242 | moves |
| 243 | to the next character. |
| 244 | If that character is zero, |
| 245 | .B sgopt |
| 246 | moves |
| 247 | back to the beginning of the cmdarg, |
| 248 | and returns |
| 249 | .BR sgoptdone . |
| 250 | If the character is a minus sign, |
| 251 | .B sgopt |
| 252 | moves to the beginning of the next cmdarg, |
| 253 | and returns |
| 254 | .BR sgoptdone . |
| 255 | |
| 256 | .B Stage three: |
| 257 | .B sgopt |
| 258 | records the current character, |
| 259 | .IR c , |
| 260 | and moves to the next character. |
| 261 | There are three possibilities: |
| 262 | (1) |
| 263 | .I c |
| 264 | is an option character without optarg in |
| 265 | .IR opts , |
| 266 | or |
| 267 | (2) |
| 268 | .I c |
| 269 | is an option character with optarg in |
| 270 | .IR opts , |
| 271 | or |
| 272 | (3) |
| 273 | .I c |
| 274 | does not appear in |
| 275 | .IR opts . |
| 276 | |
| 277 | (1) |
| 278 | If |
| 279 | .I c |
| 280 | appears as an option character without optarg in |
| 281 | .IR opts , |
| 282 | .B sgopt |
| 283 | returns |
| 284 | .IR c . |
| 285 | |
| 286 | (2) |
| 287 | If |
| 288 | .I c |
| 289 | appears as an option character with optarg in |
| 290 | .IR opts , |
| 291 | .B sgopt |
| 292 | sets |
| 293 | .B sgoptarg |
| 294 | to the current position, |
| 295 | and moves to the next cmdarg. |
| 296 | If |
| 297 | .B sgoptarg |
| 298 | is nonempty, |
| 299 | .B sgopt |
| 300 | returns |
| 301 | .IR c . |
| 302 | |
| 303 | Then |
| 304 | .B sgopt |
| 305 | sets |
| 306 | .B sgoptarg |
| 307 | to |
| 308 | the current cmdarg. |
| 309 | If |
| 310 | the current cmdarg is null, |
| 311 | or past |
| 312 | .IR argc , |
| 313 | .B sgopt |
| 314 | sets |
| 315 | .B sgoptproblem |
| 316 | to |
| 317 | .I c |
| 318 | and returns ?. |
| 319 | Otherwise |
| 320 | .B sgopt |
| 321 | moves to the next |
| 322 | argument |
| 323 | and returns |
| 324 | .IR c . |
| 325 | |
| 326 | (2) |
| 327 | If |
| 328 | .I c |
| 329 | does not appear in |
| 330 | .IR opts , |
| 331 | .B sgopt |
| 332 | sets |
| 333 | .B sgoptproblem |
| 334 | to |
| 335 | .I c |
| 336 | and returns ?. |
| 337 | .SH "SYNTAX NOTE" |
| 338 | .B sgopt |
| 339 | is actually a macro abbreviation for |
| 340 | .BR subgetopt . |
| 341 | The external |
| 342 | .B sg |
| 343 | variables are also macros |
| 344 | for |
| 345 | .BR subget . |
| 346 | These macros are defined in |
| 347 | .BR <subgetopt.h> , |
| 348 | unless |
| 349 | .B SUBGETOPTNOSHORT |
| 350 | is defined |
| 351 | when |
| 352 | .B <subgetopt.h> |
| 353 | is included. |
| 354 | .SH VERSION |
| 355 | subgetopt version 0.9, 931129. |
| 356 | .SH AUTHOR |
| 357 | Placed into the public domain by Daniel J. Bernstein. |