BidiLink, SOcat, RLwrap - Linux utilities for administrator

bidilink< is a general purpose Unix tool for linking two bidirectional data streams together. It extends the standard Unix "filter" paradigma to bidrectional streams.

socat< is a relay for bidirectional data transfer between two independent data channels. Each of these data channels may be a file, pipe, serial device, pseudo terminal, a socket, an SSL socket, proxy CONNECT connection, a file descriptor, readline, a program, or a combination of these.

rlwrap< is a wrapper that uses the GNU readline library to allow the editing of keyboard input for any other command. Input history is kept between invocations, separately for each command; history completion and search work as in bash and completion word lists can be specified on the command line.