Use of noclobber
When setting 'noclobber' overwriting the content of an existing file by the '>' redirection operator will not be possible. You might have typed '>' to redirect the output of a certain command to an existing file, while you intended to use '>>' redirection operator. This is where 'noclobber' comes in action, preventing you from accidentally deleting the content of the existing file.
How to use it
ls > list
Try setting noclobber
set -o noclobber'
Try again
ls > list bash: list: cannot overwrite existing file
How to overwrite the file even with noclobber set
If you are determined to overwrite the file you can use the '>|' method. Thus
ls >| list
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