请问参数列表传递字符串报价在C exec命令？ [英] Does the argument list pass the string quotes to exec command in C?

问题描述

我使用 execvp 为execing一个新的进程的命令的grep -l晚* 。这里是我的code：

I am using execvp for execing a new process for the command grep -l night *. Here is my code:

char * argument[5];
char keyword[] = "night";

argument[0] = (char *) malloc (sizeof(char)*25);
argument[1] = (char *) malloc (sizeof(char)*25);
argument[2] = (char *) malloc (sizeof(char)*25);
argument[3] = (char *) malloc (sizeof(char)*25);
argument[4] = (char *) malloc (sizeof(char)*25);

argument[0] = "grep";
argument[1] = "-l";
strcpy(argument[2],keyword);
argument[3] = "*";
argument[4] = NULL;

execvp ("grep", argument);

但我正在逐渐从该程序的输出为grep的：*：没有这样的文件或目录
这是不正确的，在列表中从壳的结果执行相同的命令
其中包含文本空中飞人的文件。我不怀疑 * 命令列表正在
发送与引号中的字符串 EXEC 。是我的假设是正确的？如果是的话我怎么能纠正这个问题？任何帮助将是非常美联社preciated。

But I am getting the output from this program as "grep: *: No such file or directory" which is incorrect as executing the same command from the shell results in the list of files which contain the text "night". I do suspect that the * in the command list is being sent as a string with quotes to exec. Is my assumption correct? If so how can I rectify this problem? Any help would be highly appreciated.

推荐答案

grep的不理解*的说法。通常情况下，外壳程序扩展等参数（这就是所谓的的通配的 ）。当然，由于 EXEC 功能不启动一个shell，你没有得到该功能。

Grep does not understand the "*" argument. Usually the shell expands such arguments (it's called globbing). Of course, since exec functions don't start a shell, you don't get that functionality.

您可以：

其中
• 使用功能不的启动shell（系统（3），的popen（3））


• 使用 水珠（3） ，基本上从事贝壳工作

• Use functions which do start a shell (system(3), popen(3))
• Use glob(3), essentially doing the shells job

您也许可以写，因为这（未经检验）

You could probably write it as this (untested):

glob_t globbuf;
globbuf.gl_offs = 3;

/* Globbing magic. */
glob("*", GLOB_DOOFFS, NULL, &globbuf);

/* That's what the 3 was for. */
globbuf.gl_pathv[0] = "grep";
globbuf.gl_pathv[1] = "-l";
globbuf.gl_pathv[2] = "night";

/* Conveniently, the list is NULL-terminated. */
execvp("grep", globbuf.gl_pathv);

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