C++ 50行代码实现Linux ls -l 命令

说明：此代码并不是实现完整的 ls 命令

// filename:myls_l.cpp
#include <iostream>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <pwd.h>
#include <grp.h>
#include <time.h>
#include <string>

int main(int argc, char *argv[])
{
     using std::cout;
     using std::endl;
     using std::string;
     struct stat st;
     struct passwd *wd;
     struct group *gp;
     string tm;
     int ret = stat(argv[1], &st);
     if(ret == -1) { cout << "open error" << endl; return -1; }
     if(S_ISREG(st.st_mode))       cout << "-";
     else if(S_ISDIR(st.st_mode))      cout << "d";
     else if(S_ISCHR(st.st_mode))   cout << "c";
     else if(S_ISBLK(st.st_mode))   cout << "b";
     else if(S_ISLNK(st.st_mode))   cout << "l";
     else if(S_ISFIFO(st.st_mode))  cout << "f";
     else if(S_ISSOCK(st.st_mode))  cout << "s";
     if (st.st_mode & S_IRUSR)      cout << "r";
     else                   cout << "-";
     if (st.st_mode & S_IWUSR)      cout << "w";
     else                   cout << "-";
     if (st.st_mode & S_IXUSR)      cout << "x";
     else                   cout << "-";
     if (st.st_mode & S_IRGRP)      cout << "r";
     else                   cout << "-";
     if (st.st_mode & S_IWGRP)      cout << "w";
     else                   cout << "-";
     if (st.st_mode & S_IXGRP)      cout << "x";
     else                   cout << "-";
     if (st.st_mode & S_IROTH)      cout << "r";
     else                   cout << "-";
     if (st.st_mode & S_IWOTH)      cout << "w";
     else                   cout << "-";
     if (st.st_mode & S_IXOTH)      cout << "x";
     else                   cout << "-";
     cout << " " << st.st_nlink;
     wd = getpwuid(st.st_uid);
     cout << " " << wd->pw_name;
     gp = getgrgid(st.st_gid);
     cout << " " << gp->gr_name;
     cout << " " << st.st_size;
     tm = ctime(&st.st_mtime);
     cout << " " << tm.substr(4, 12);
     cout << " " << argv[1] << endl;
     return 0;
}

调用方法：

$ g++ -o myls_l myls_l.cpp
$ ./myls_l myls_l.cpp