debian man page for open_excl

open_excl(3)						     Library Functions Manual						      open_excl(3)

NAME
       open_excl - open a file for exclusive writing

SYNTAX
       #include <open.h>

       int open_excl(const char *filename);

DESCRIPTION
       open_excl  opens the file filename for writing and returns the file handle.  The file may not exist before the call to open_excl.  The file
       will be created with mode 0600.

       If there was an error creating the file, open_excl returns -1 and sets errno accordingly.

       Since open_excl relies on the O_EXCL flag to open, it does not work reliably over NFS (the NFS protocol is broken)  and	must  be  emulated
       using  a  lock  file  (create  a file with a unique file name and link(2) it to the lock file.  Then stat the lock file and see if the link
       count is 2).

SEE ALSO
       open(2)

																      open_excl(3)