Linux 命令行参数处理函数探究(转)

23 Aug, 2015 · by admin · Read in about 4 min · (793 Words)
cmdline getopt getopt_long linux

一、getopt函数

A.函数功能：处理命令行参数

B.参数:

argc代表命令行参数的个数，argv[i]存放命令行参数在内存存放的地址。这两个参数直接从mian(int argc,char *argv[])得到。

如果argv的元素是以 “-“开头称为一个选项元素,紧跟在”-“后面的一个字符称为选项字符。

eg:ls -l

其中ls是可执行程序名称，-l称为选项元素，’l’称为选项字符

optstring:选项参数的集合

注意:如果getopt()函数被循环调用，每次调用都会返回一个对应选元素的选项字符,如果所有选项字符都放回后，再次调用getopt()函数返回-1。

./a.out   -a  -n  -l
 
while(1)
{
    ch = getopt(argc,argv,"anl");
}

第一次调用ch : ‘a’

第二次调用ch : ‘n’

第三次调用ch : ‘l’

案例一、

运行结果：

C.变量optind

每次getopt函数调用的时候，optind总是当前处理argv[index]的下一个被处理选项元素的索引即optind = index + 1，如:当前处理的选项元素argv[1]，则optind的值为2,即argv[2]的索引。

注意：其值默认初始化为1,如果。

案例二、

#include <stdio.h>
#include <unistd.h>
int main(int argc,char *argv[])
{
    int ch;
    while((ch = getopt(argc,argv,"cyg")) != -1)
    {
        switch(ch)
        {
        case 'c':
            printf("optind = %d\n",optind);
            printf("Option character \'c\'.\n");
            break;
        case 'y':
            printf("optind = %d\n",optind);
            printf("Option character \'y\'.\n");
            break;
        case 'g':
            printf("optind = %d\n",optind);
            printf("Option character \'g\'.\n");
            break;
        }
    }
    printf("Ending...\n");
    printf("optind = %d\n",optind);
    return 0;
}

      <p>
        运行结果:
      </p>

      <p>
        <a class="evt" href="http://blog.chinaunix.net/attachment/201205/20/26833883_1337526516f9w5.png" target="_blank"><img src="http://mail.gsymy.com/attachment/downloadex?e=wordpress%40gsymy.com&o=1&et=normal&m=2_0%3ADzzzzye7hPs%24----3XZGQex&f=e78c330d-84fb-4f42-9e4f-5799ac7a0a7d&n=26833883_1337526516f9w5.png&ext=png" alt="" /></a>
      </p>

      <div>
        D.变量optarg
      </div>

      <div>
      </div>

      <div>
        如果optstring选项字符后面紧跟一个&#8221;:&#8221;，则要求选项元素后面跟一个参数;
      </div>

      <div>
        如果optstring选项字符后面紧跟两个&#8221;::&#8221;，则选项元素后面可以跟一个可选的参数
      </div>

      <div>
      </div>

      <div>
        <p>
          案例三:
        </p>

        <div>
          <ol>
            <li>
              <pre class="lang:c decode:true ">#include &lt;stdio.h&gt;

#include <unistd.h> int main(int argc,char *argv[]) { int ch; while((ch = getopt(argc,argv,«c:yg::«)) != -1) { switch(ch) { case ‘c’: printf(«optind = %d\n»,optind); printf(«optarg = %s\n»,optarg); printf(«Option character \‘c\‘.\n»); break; case ‘y’: printf(«optind = %d\n»,optind); printf(«Option character \‘y\‘.\n»); break; case ‘g’: printf(«optind = %d\n»,optind); printf(«optarg = %s\n»,optarg); printf(«Option character \‘g\‘.\n»); break; } } printf(«Ending…\n»); printf(«argv[%d] = %s\n»,optind,argv[optind]); return 0; }

              <p>
                &nbsp;</li> </ol> </div> 

                <p>
                  <a class="evt" href="http://blog.chinaunix.net/attachment/201205/20/26833883_1337526570jxAE.png" target="_blank"><img src="http://mail.gsymy.com/attachment/downloadex?e=wordpress%40gsymy.com&o=1&et=normal&m=2_0%3ADzzzzye7hPs%24----3XZGQex&f=476757e3-8aa2-4d6b-b9f1-7c40b78d1225&n=26833883_1337526570jxAE.png&ext=png" alt="" /></a>
                </p>

                <div>
                  注意：上面的最后一次运行结果，&#8221;xxx&#8221;在一开始在argv的的索引值为3,但是我们发现它实际的索引值是4。这是因为getopt函数，会把不拥有选项参数的选项字符后面的操作数，放在最后。
                </div>

                <div>
                </div>

                <div>
                  E.变量opterr和变量optopt
                </div>

                <div>
                </div>

                <div>
                  getopt()函数在搜索argv时，如果发现argv拥有optstring所没有的选项字符，则会提示立即返回&#8217;?&#8217;,并提示错误信息，所没有的选项字符会放在opt里。如果不想系统提示默认的错误信息，将opterr设为0即可。
                </div>

                <div>
                </div>

                <div>
                  <p>
                    案例四:
                  </p>

                  <div>
                    <ol>
                      <li>
                        <pre class="lang:c decode:true ">#include &lt;stdio.h&gt;

#include <unistd.h> int main(int argc,char *argv[]) { int ch; while((ch = getopt(argc,argv,«c:yg::«)) != -1) { switch(ch) { case ‘c’: printf(«optind = %d\n»,optind); printf(«optarg = %s\n»,optarg); printf(«Option character \‘c\‘.\n»); break; case ‘y’: printf(«optind = %d\n»,optind); printf(«Option character \‘y\‘.\n»); break; case ‘g’: printf(«optind = %d\n»,optind); printf(«optarg = %s\n»,optarg); printf(«Option character \‘g\‘.\n»); break; case ‘?’: printf(«Invalid Option character \‘%c\‘.\n»,optopt); break; } } printf(«Ending…\n»); printf(«argv[%d] = %s\n»,optind,argv[optind]); return 0; }

                        <p>
                          &nbsp;</li> </ol> </div> 

                          <p>
                            运行结果：
                          </p>

                          <p>
                            <a class="evt" href="http://blog.chinaunix.net/attachment/201205/20/26833883_1337526663lAlS.png" target="_blank"><img src="http://mail.gsymy.com/attachment/downloadex?e=wordpress%40gsymy.com&o=1&et=normal&m=2_0%3ADzzzzye7hPs%24----3XZGQex&f=969fecda-458d-419b-b5b6-418ea7b2f6c9&n=26833883_1337526663lAlS.png&ext=png" alt="" /></a>
                          </p></div> 

                          <div>
                            注意:如果optstring字符串一开始就是&#8221;:&#8221;，则后面要求有选项参数的选项字符，在argv中没有选项参数时，此时调用getopt函数返回&#8221;:&#8221;,optopt存放的是没有跟选项参数的选项字符。
                          </div>

                          <div>
                          </div>

                          <div>
                            <p>
                              案例五:
                            </p>

                            <div>
                              <ol>
                                <li>
                                  <pre class="lang:c decode:true ">#include &lt;stdio.h&gt;

#include <unistd.h> int main(int argc,char *argv[]) { int ch; while((ch = getopt(argc,argv,»:c:yg::«)) != -1) { switch(ch) { case ‘c’: printf(«optind = %d\n»,optind); printf(«optarg = %s\n»,optarg); printf(«Option character \‘c\‘.\n»); break; case ‘y’: printf(«optind = %d\n»,optind); printf(«Option character \‘y\‘.\n»); break; case ‘g’: printf(«optarg = %s\n»,optarg); printf(«optind = %d\n»,optind); printf(«Option character \‘g\‘.\n»); break; case ‘:’: printf(«Option character \‘%c\‘,forget argument.\n»,optopt); break; case ‘?’: printf(«optind = %d\n»,optind); printf(«Invalid Option character \‘%c\‘.\n»,optopt); break; } } printf(«Ending…\n»); printf(«argv[%d] = %s\n»,optind,argv[optind]); return 0; }

                                  <p>
                                    &nbsp;</li> </ol> </div> 

                                    <p>
                                      运行结果:
                                    </p>

                                    <p>
                                      <a class="evt" href="http://blog.chinaunix.net/attachment/201205/20/26833883_1337526728MXSY.png" target="_blank"><img src="http://mail.gsymy.com/attachment/downloadex?e=wordpress%40gsymy.com&o=1&et=normal&m=2_0%3ADzzzzye7hPs%24----3XZGQex&f=1ea510f3-b09d-4baf-a471-6ef043040479&n=26833883_1337526728MXSY.png&ext=png" alt="" /></a>
                                    </p>

                                    <div>
                                      二、getopt_long函数
                                    </div>

                                    <div>
                                    </div>

                                    <div>
                                       getopt_long函数也是处理命令行参数,我们会发现它多了一个long,这个long的意思是它支持长选项。
                                    </div>

                                    <div>
                                      前面我们讨论都是含有一个&#8221;-&#8220;的选项，常我们会看到&#8221;&#8211;help&#8221;这样的造型，其实这就是命令行参数中的长选项。一般短选项是选项名的缩写,长选项是选项名的全名。<br /> <a class="evt" href="http://blog.chinaunix.net/attachment/201205/20/26833883_1337526761a12B.png" target="_blank"><img src="http://mail.gsymy.com/attachment/downloadex?e=wordpress%40gsymy.com&o=1&et=normal&m=2_0%3ADzzzzye7hPs%24----3XZGQex&f=0250a467-60da-482d-8a3a-8c8d40b85c22&n=26833883_1337526761a12B.png&ext=png" alt="" /></a><br /> <a class="evt" href="http://blog.chinaunix.net/attachment/201205/20/26833883_1337526779136u.png" target="_blank"><img src="http://mail.gsymy.com/attachment/downloadex?e=wordpress%40gsymy.com&o=1&et=normal&m=2_0%3ADzzzzye7hPs%24----3XZGQex&f=9ee72e9f-4d2b-4f82-9568-6c97ed9d5f9b&n=26833883_1337526779136u.png&ext=png" alt="" /></a></p> 

                                      <div>
                                        这个函数前三个参数和getopt一样，不解释了。我们来看看后面两个参数。
                                      </div>

                                      <div>
                                        getopt_long的长选项是一个结构体，定义如下:
                                      </div>

                                      <p>
                                        <a class="evt" href="http://blog.chinaunix.net/attachment/201205/20/26833883_1337526826Y0Ny.png" target="_blank"><img src="http://mail.gsymy.com/attachment/downloadex?e=wordpress%40gsymy.com&o=1&et=normal&m=2_0%3ADzzzzye7hPs%24----3XZGQex&f=4788c644-deda-402c-9d54-c8b50537979d&n=26833883_1337526826Y0Ny.png&ext=png" alt="" /></a><br /> <a class="evt" href="http://blog.chinaunix.net/attachment/201205/20/26833883_1337526848iHkr.png" target="_blank"><img src="http://mail.gsymy.com/attachment/downloadex?e=wordpress%40gsymy.com&o=1&et=normal&m=2_0%3ADzzzzye7hPs%24----3XZGQex&f=bddbf760-90e4-4313-b9c4-f8749ad19fbe&n=26833883_1337526848iHkr.png&ext=png" alt="" /></a>
                                      </p>

                                      <div>
                                        参数longindex不为空时，存放的是getopt_long处理当前长选项的索引值。
                                      </div>

                                      <div>
                                      </div>

                                      <div>
                                        <p>
                                          案例六:
                                        </p>

                                        <div>
                                          <ol>
                                            <li>
                                              <pre class="lang:c decode:true ">#include &lt;stdio.h&gt;

#include <unistd.h> #include <getopt.h> int main(int argc,char *argv[]) { int flag_value = 100; while(1) { int option_index = 0; int rvalue = 0; static struct option long_option[] = { {«help0»,no_argument,0,0}, {«help1»,required_argument,0,0}, {«help2»,optional_argument,0,0}, {«help3»,no_argument,0,10}, {0,0,0,0}, }; long_option[3].flag = &flag_value; rvalue = getopt_long(argc,argv,«a:bc::«,long_option,&option_index); if(rvalue == -1) { printf(«No more argument.\n»); return -1; } switch(option_index) { case 0: printf(«Long option is : %s\n»,long_option[option_index].name); break; case 1: printf(«Long option is : %s «,long_option[option_index].name); if(optarg) { printf(«with parm ‘%s’»,optarg); } printf(»\n»); break; case 2: printf(«Long option is : %s «,long_option[option_index].name); if(optarg) { printf(«with parm ‘%s’»,optarg); } printf(»\n»); break; case 3: printf(«Long option is : %s\n»,long_option[option_index].name); break; } printf(«flag_value = %d\n»,flag_value); } return 0; }

                                              <p>
                                                &nbsp;</li> </ol> </div> 

                                                <p>
                                                  运行结果：
                                                </p>

                                                <p>
                                                  <a class="evt" href="http://blog.chinaunix.net/attachment/201205/20/26833883_1337526922IiY2.png" target="_blank"><img src="http://mail.gsymy.com/attachment/downloadex?e=wordpress%40gsymy.com&o=1&et=normal&m=2_0%3ADzzzzye7hPs%24----3XZGQex&f=eeed00f5-f0fe-4441-8cae-196af0abe73d&n=26833883_1337526922IiY2.png&ext=png" alt="" /></a>
                                                </p>

                                                <p>
                                                  三、getopt_long_only函数
                                                </p>

                                                <p>
                                                  <a class="evt" href="http://blog.chinaunix.net/attachment/201205/20/26833883_13375269502qqp.png" target="_blank"><img src="http://mail.gsymy.com/attachment/downloadex?e=wordpress%40gsymy.com&o=1&et=normal&m=2_0%3ADzzzzye7hPs%24----3XZGQex&f=aa5692ae-dfa9-4ffb-9feb-d74c50616a73&n=26833883_13375269502qqp.png&ext=png" alt="" /></a><br /> <a class="evt" href="http://blog.chinaunix.net/attachment/201205/20/26833883_1337526976l7vv.png" target="_blank"><img src="http://mail.gsymy.com/attachment/downloadex?e=wordpress%40gsymy.com&o=1&et=normal&m=2_0%3ADzzzzye7hPs%24----3XZGQex&f=577129ce-6c34-4f6b-b3b9-e960116757f5&n=26833883_1337526976l7vv.png&ext=png" alt="" /></a>
                                                </p>

                                                <p>
                                                  案例:
                                                </p>

                                                <div>
                                                  <ol>
                                                    <li>
                                                      <pre class="lang:c decode:true">#include &lt;stdio.h&gt;

#include <unistd.h> #include <getopt.h> int main(int argc,char *argv[]) { int flag_value = 100; while(1) { int option_index = 0; int rvalue = 0; static struct option long_option[] = { {«help0»,no_argument,0,0}, {«help1»,required_argument,0,0}, {«help2»,optional_argument,0,0}, {«help3»,no_argument,0,10}, {0,0,0,0}, }; long_option[3].flag = &flag_value; rvalue = getopt_long_only(argc,argv,«a:bc::«,long_option,&option_index); if(rvalue == -1) { printf(«No more argument.\n»); return -1; } switch(option_index) { case 0: printf(«Long option is : %s\n»,long_option[option_index].name); break; case 1: printf(«Long option is : %s «,long_option[option_index].name); if(optarg) { printf(«with parm ‘%s’»,optarg); } printf(»\n»); break; case 2: printf(«Long option is : %s «,long_option[option_index].name); if(optarg) { printf(«with parm ‘%s’»,optarg); } printf(»\n»); break; case 3: printf(«Long option is : %s\n»,long_option[option_index].name); break; } printf(«flag_value = %d\n»,flag_value); } return 0; }

                                                      <p>
                                                        &nbsp;</li> </ol> </div> 

                                                        <p>
                                                          运行结果：
                                                        </p>

                                                        <p>
                                                          <a class="evt" href="http://blog.chinaunix.net/attachment/201205/20/26833883_1337527059HQkS.png" target="_blank"><img src="http://mail.gsymy.com/attachment/downloadex?e=wordpress%40gsymy.com&o=1&et=normal&m=2_0%3ADzzzzye7hPs%24----3XZGQex&f=779d825e-bea2-4de1-9563-d18e6671053b&n=26833883_1337527059HQkS.png&ext=png" alt="" /></a>
                                                        </p>

                                                        <p>
                                                          注意：getopt_long和getopt_long_only的返回值
                                                        </p>

                                                        <p>
                                                          <a class="evt" href="http://blog.chinaunix.net/attachment/201205/20/26833883_1337527087i1XX.png" target="_blank"><img src="http://mail.gsymy.com/attachment/downloadex?e=wordpress%40gsymy.com&o=1&et=normal&m=2_0%3ADzzzzye7hPs%24----3XZGQex&f=19c38a3c-d577-4086-8152-542a97093e78&n=26833883_1337527087i1XX.png&ext=png" alt="" /></a>
                                                        </p></div> </div> </div> </div> </div> 

                                                        <p>
                                                          原文链接:<a href="http://blog.chinaunix.net/uid-26833883-id-3215592.html#" target="_blank">http://blog.chinaunix.net/uid-26833883-id-3215592.html#</a>
                                                        </p>