I/O redirection is very useful especially when we want to disgard errors our redirect output of a some shell command/program to a file. There are three kinds of redirections:
- Redirect stdin fd to a file such as
cat < file- The file descriptor that we want to redirect has to be infront of
<. In the case of redirecting stdin,0<is the same as<.
- The file descriptor that we want to redirect has to be infront of
- Redirect stdout/stderr to a file such as
ls dir > tmporls dir 2>error- The file descriptor that we want to redirect has also to be in the front of
>. In the case of redirecting stdout,1>is the same as>. - If we want to redirect some file descriptor fd0 to another file descriptor fd1, we can do
fd0>fd1. >truncates the file we’re redirecting the output to and writes the new output>>appends to the file we’re redirecting the output to, and doesn’t overwrite the old context. Example:cat /etc/passwd >> tmp.
- The file descriptor that we want to redirect has also to be in the front of