What is the use of file descriptor 255 in bash process
The open files are 0 (stdin), 1 (stdout), and 2 (stderr). 255 is a little trick that bash uses to keep a copy of these for when they are redirected. This is specific to bash.
Source: https://books.google.com/books?id=wWjqCF9HLfYC&pg=PA231
Example:
echo foo 1>/dev/null 2>/dev/null >/proc/$$/fd/255Output:
foo