Bash Reference Manual
3.6.2 Redirecting Output
Redirection of output causes the file whose name results from
the expansion of word
to be opened for writing on file descriptor n,
or the standard output (file descriptor 1) if n
is not specified. If the file does not exist it is created;
if it does exist it is truncated to zero size.
The general format for redirecting output is:
If the redirection operator is `>', and the
option to the
set builtin has been enabled, the redirection
will fail if the file whose name results from the expansion of
word exists and is a regular file.
If the redirection operator is `>|', or the redirection operator is
`>' and the
noclobber option is not enabled, the redirection
is attempted even if the file named by word exists.