在linux下利用c语言实现的进程树的打印，主要通过/proc下的目录中的进程文件，获取status中的进程信息内容，然后利用递归实现进程树的打印-Under the linux process using c language to print the tree, primarily through/proc directory under the file in the process, the process to obtain status information, and then use recursion to print the process tree