É um desvio explícito da opção noclobber
.
Dessa forma, você pode sobrescrever o arquivo mesmo com noclobber
set.
Veja o link
De man bash
:
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 to the set builtin command is not enabled, the redirection is attempted even if the file named by word exists.