20 Sep: "Force Overwrite" Bash Redirection Operator

There's a bash shell option, noclobber, that prevents overwriting existing files:

$ set -C      # or set -o noclobber

When set bash will report an error if you try to redirect something to an existing file:

$ echo "hi" > test
bash: test: cannot overwrite existing file

You could check that the noclobber option is responsible for this by looking at what SHELLOPTS are active:

$ echo $SHELLOPTS
braceexpand:emacs:hashall:histexpand:history:interactive-comments:monitor:noclobber
$ set | grep SHELLOPTS
SHELLOPTS=braceexpand:emacs:hashall:histexpand:history:interactive-comments:monitor:noclobber

You could unset noclobber, but instead, if you know better and know you want to overwrite, you could use the special >| redirection operator. From the bash man page:

"If the redirection operator is >|, or the redirection operator is > and the noclobber option to the set builtin command is not enabled, the redirection is attempted even if the file named by word exists."

$ echo "hi" >| test

If you want to see all the shell options that you can set, and what they do, run "help set".