system函数源码

#include <sys/types.h> #include <sys/wait.h> #include <errno.h> #include <unistd.h> int system(const char * cmdstring) { pid_t pid; int status; if(cmdstring == NULL){ return (1); } if((pid = fork())<0){ status = -1; } else if(pid = 0){ execl("/bin/sh", "sh", "-c", cmdstring, (char *)0); exit(127); } else{ while(waitpid(pid, &status, 0) < 0){ if(errno != EINTER){ status = -1; break; } } } return status; }