In this source code <http://man7.org/tlpi/code/online/dist/sysinfo/procfs_pidmax.c.html> the file `/proc/sys/kernel/pid_max` is first simply read (using the `read` syscall) and then simply written (using the `write` syscall).

Why is it no necessary to `lseek` to the beginning before writing? I thought the file-offset pointer is the same for read's and write's (that's what the author of the associated books says).