file exists?

raven · 10-26-2003, 05:38 AM

Hello

I am programming c in lunux. I need to determine weather a file exists, but without opening it. Is there a way to do this?

I dont want to use open("file",0) and check the return value...

Thanks

raven

slakmagik · 10-26-2003, 06:09 AM

Never mind - that was bash - dunno if it works in C.

I'm an idiot.

kev82 · 10-26-2003, 06:40 AM

look up the stat sytem call

man 2 stat

Hko · 10-26-2003, 07:05 AM

Code:

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>

int main(int argc, char **argv)
{
     char *filename;
     int result;
     struct stat statinfo;

     if (argc != 2) {
	  fprintf(stderr, "Usage: %s [<file>]\n", argv[0]);
	  return 1;
     }
     filename = argv[1];
     result = stat(filename, &statinfo);
     if (result < 0) {
	  if (errno == ENOENT) {
	       printf("File %s does not exist\n", filename);
	       return 0;
	  } else {
	       perror(*argv);
	       return 1;
	  }
     }
     printf("File %s exists, and is a ", filename);
     switch (statinfo.st_mode & S_IFMT) {
     case S_IFREG:  printf("regular file.\n"); break;
     case S_IFSOCK: printf("filesystem socket.\n"); break;
     case S_IFLNK:  printf("symbolic link.\n"); break;
     case S_IFBLK:  printf("block device file.\n"); break;
     case S_IFDIR:  printf("directory.\n"); break;
     case S_IFCHR:  printf("character device file.\n"); break;
     case S_IFIFO:  printf("filesystem pipe (fifo) file.\n"); break;
     default:  printf("unknown type of file.\n"); break;
     }
     return 0;
}

SaTaN · 10-26-2003, 07:06 AM

Code:

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
main()
{
        struct stat BUF;
        if(stat("/path/to/where/file/exists",&BUF)==-1)
        {
                printf("File doesn't exist\n");
        }
}

Hope this does it for you

Hko · 10-26-2003, 07:23 AM

That's not reliable.
If stat() returns -1, that doesn't necessarily mean the file does not exist.

SaTaN · 10-26-2003, 07:27 AM

Yeah you are right ...
You need to check errono for the correct error.

Thanks for pointing that mistake.

raven · 10-26-2003, 07:44 AM

Wow :-) so many replies. Thanks for all, Now I've got it :-)

raven