Does someone knows what does errno 72 means
I got this error when fwriting a structure and still the file is being
created.
I saw something on the net saying that this is caused when trying to
access different file system
You can use perror or strerror to get a message related to the error.
Specific errno values aren't portable. (On several systems I've just
checked, it means "RPC structure is bad", "Multihop attempted",
"Locked lock was unmapped", or "A connection is ended by software.".)
But it won't necessarily be meaningful. The fwrite() function doesn't
necessarily set errno on an error -- and any function can set errno to
a non-zero value whether it fails or not. (errno might be set as a
side effect of calling a lower-level function.) You can (sometimes)
use errno to determine which error occurred, but not to find out
whether an error occurred or not.
If you set errno to 0 before calling fwrite(), *and* the value
returned by fwrite() indicates that an error occurred, *and* error is
non-zero after the call, then it's likely (but not guaranteed) that
the value of errno will then be meaningful.