Holger Kiehl wrote:
> What is the quickest way to test if a file or directory exist.
> I can think of three different system calls that can be used:
> access(), stat() and open(). Writting a little test program I
> found that this is also the order of which is the quickest,
> that is access() is the quickest and open() the slowest. The code
> for the test programms is shown below.
>
> The question I have is there any other system call that I can use
> that would be cheaper then access(). Even if they are linux specific
> system calls I would like to know.
>
> Thanks,
> Holger
>
> access.c
>
> #include <stdio.h>
> #include <string.h>
> #include <unistd.h>
> #include <errno.h>
>
> #define MAX_LOOPS 5000000
>
> int main(void)
> {
> unsigned int i;
>
> for (i = 0; i < MAX_LOOPS; i++)
> {
> if (access("abcd", R_OK) != 0)
If you just want to check for existence, use F_OK. If you use R_OK,
the call will fail if you don't have read permission for the file.
OTOH, if access(..., R_OK) succeeds, that doesn't necessarily mean
that opening the file for read will succeed.
--
Glynn Clements <glynn@xxxxxxxxxxxxxxxxxx>
-
To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
