How do I override the bash “noclobber” option?

Question

The bash noclobber option prevents one from overwriting files with redirection. But sometimes I really want to. csh has a similar option and it can be over-ridden by putting a ! before the filenames. Is there any way to do this with bash?

Answer 1

Yes. Append | to the redirection operator to form >|. This is in § 3.6.2 of the Bash Reference Manual, q.v.

If the redirection operator is ‘>’, and the noclobber 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.

Visit this tutorial about the noclobber option. It might be of help.

Answer 2

Use | ("pipe") instead of ! ("bang"), as in:

echo done >| out

However, >|& and &>| don't work—if you want to override noclobber and redirect stderr, do it like this:

mixout stdout stderr >| out 2>&1