Question

I’m trying to find a file using BFS and recursion , where given a directory and a file , the algorithm needs to check the given directory or all its sub directories .

Now, when I check a directory, sometimes I have an annoying ~ tilde that pops up at the end of the char* string . I’ve checked with some printf-S and came to a conclusion that the ~ is actually a part of the file-name .

How could that be? Sid I do something wrong?

Here is part of the recursion :

int scanner(char *dirname,char *entries , char * directory , char * file)
{

    struct stat st;


    /* scan the directory and store the entries in a buffer */
   DIR *dir;
   struct dirent *ent;
   int count=1;
   char name[256];

   if ((dir = opendir(dirname)) == NULL)
   {
     perror("Unable to open directory");
     return(0);
   }

   while ((ent = readdir(dir)) != NULL)
       count++;

   rewinddir(dir);

   // here we copy all the file-names from the directory into the buffer
   // we copy all the names using sprintf and strcpy


   while ((ent = readdir(dir)) != NULL)
   {

       strcpy(name,ent->d_name);


       if (strcmp(name , file) == 0 )

       {
           printf("\nFile was found  !!! in first IF\n");
           printf("\n-----------------------------------------------------------------------\n");

           if (stat(name, &st) < 0) {
                perror(name);
                putchar('\n');
                continue;
            }

           printfile(&st , name);
           printf("\nStringer 'name' is : %s" , name);
           printf("\nThe length of %s is %d" , name , strlen(name));
       }

       else // try
       {
           int length = strlen(name);
           char try[length+2];
           strcpy(try,name);
           try[length+1] = '~';
           try[length+2] = '\0';


           printf("\nThe 'name' is : %s" , name);
           printf("\nThe length of %s is %d" , name , strlen(name));
           printf("\nPrint try %s\n" , try);
           if (strcmp(try , file) == 0 )
               printf("\nFile was found  !!! in second IF\n");
       }


       sprintf(entries,"%s",name);
       entries = entries+strlen(name)+1;

       printf("\nStringer name :%s" , name);

       count++;
   }

   if (closedir(dir) != 0)
     perror("Unable to close directory");

     return(count);
}

And from terminal I hit ./exer4 check david.txt , and got :

The 'name' is : ..
The length of .. is 2
Print try ..

Stringer name :..
The 'name' is : .
The length of . is 1
Print try .

Stringer name :.
The 'name' is : insideCheck
The length of insideCheck is 11
Print try insideCheck

Stringer name :insideCheck
The 'name' is : david.txt~
The length of david.txt~ is 10
Print try david.txt~

Stringer name :david.txt~
The 'name' is : doc.txt~
The length of doc.txt~ is 8
Print try doc.txt~

Answer 1

Having a tilde (~) as a suffix means the file is an automatic backup, for instance Emacs tends to create these. Since your example shows tilde-suffixed text (.txt) files, it seems very likely that Emacs is the culprit here.

So there’s nothing wrong with your code, any tool should show these files since they’re actually there.