chmod.c

在linux9中实现修改文件权限

#include <sys/stat.h>
#include <stdio.h>
#include <sys/types.h>
#include <string.h>

int main(int argc,char *argv[])
{
    int    i;
    mode_t mode;
    if(argc < 3)
    {
       if(argc == 2)
           if(strcmp(argv[1],"--help")==0)
           {  
                printf("Usage:chmod Mode File...\n");
                exit(0);
           } 
       printf("chmod:too few argument\n");
       printf("Try 'chmod --help' for more information.\n");
       exit(0);     
     }
    if(argv[1][0] == '4')
       mode = S_IRUSR;
    else if(argv[1][0] == '6')
       mode = S_IRUSR|S_IWUSR;
    else if(argv[1][0] == '5')
       mode = S_IRUSR|S_IXUSR;
    else if(argv[1][0] == '7')
       mode = S_IRWXU;
    else if(argv[1][0] == '2')
       mode = S_IWUSR;
    else if(argv[1][0] == '3')
       mode = S_IWUSR|S_IXUSR;
    else if(argv[1][0] == '1')
       mode = S_IXUSR;
    if(argv[1][1] == '4')
       mode |=S_IRGRP;
    else if(argv[1][1] == '6')
       mode |=S_IRGRP|S_IWGRP;
    else if(argv[1][1] == '5')
       mode = S_IRGRP|S_IXGRP;
    else if(argv[1][1] == '7')
       mode |= S_IRWXG;
    else if(argv[1][1] == '2')
       mode |= S_IWGRP;
    else if(argv[1][1] == '3')
       mode |= S_IWGRP|S_IXGRP;
    else if(argv[1][1] == '1')
       mode |= S_IXGRP;
    if(argv[1][2] == '4')
       mode |=S_IROTH;
    else if(argv[1][2] == '6')
       mode |=S_IROTH|S_IWOTH;
    else if(argv[1][2] == '5')
       mode = S_IROTH|S_IXOTH;
    else if(argv[1][2] == '7')
       mode |= S_IRWXO;
    else if(argv[1][2] == '2')
       mode |= S_IWOTH;
    else if(argv[1][2] == '3')
       mode |= S_IWOTH|S_IXOTH;
    else if(argv[1][2] == '1')
       mode |= S_IXOTH;
    
    for(i=2;i<argc;i++)
    if(chmod(argv[i],mode)<0)
      {
         printf("chmod error.\n");
         exit(0);
      }
}