On Mon, Aug 25, 2003 at 02:06:06PM -0500, Bob Friesenhahn wrote: > On Mon, 25 Aug 2003, Paul Jarc wrote: > > > Bob Friesenhahn <[EMAIL PROTECTED]> wrote: > > > Creating a hard link is an atomic operation whereas a symbolic link is > > > not > > > > How so? > > It has to do with the complexity of the operation, particularly if a > network is involved. Creating a hard link does not create a new file > (allocate a new inode), it simply updates a directory table to > reference an existing file. This requires a single network request. > Most importantly, it is documented to be atomic. Creating a symbolic > link requires testing for an existing file, and then (if the file does > not exist) creating a new file, and a directory entry to reference it. > This requires multiple network transactions with an opportunity for > race-conditions. > > NAME > link - make a hard file link > > LIBRARY > Standard C Library (libc, -lc) > > SYNOPSIS > #include <unistd.h> > > int > link(const char *name1, const char *name2); > > DESCRIPTION > The link() function call atomically creates the specified directory entry > (hard link) name2 with the attributes of the underlying object pointed at > by name1. ... > > ... >
I'd rather see a link to the POSIX standard defining link as atomic. -- albert chin ([EMAIL PROTECTED]) _______________________________________________ Libtool mailing list [EMAIL PROTECTED] http://mail.gnu.org/mailman/listinfo/libtool
