我如何执行shell内置命令与C函数？
我想通过像execv C语言函数来执行Linux命令PWD（）。
I would like to execute the Linux command "pwd" through a C language function like execv().
问题是，有没有所谓的PWD的可执行文件，我不能执行回声$ PWD，因为回声也是一个内置的命令，没有可执行程序被发现。
The issue is that there isn't an executable file called "pwd" and I'm unable to execute "echo $PWD", since echo is also a built-in command with no executable to be found.
您应该执行上海-c回声$ PWD ;一般 SH -c 将执行shell命令。
You should execute sh -c echo $PWD; generally sh -c will execute shell commands.
（事实上，系统（富）定义为 EXECL（嘘，嘘，-c，富， NULL），因而适用于shell内建的。）
(In fact, system(foo) is defined as execl("sh", "sh", "-c", foo, NULL) and thus works for shell built-ins.)
如果你只想值 PWD ，使用 GETENV ，虽然
If you just want the value of PWD, use getenv, though.