4 ms·

Bash has a /dev/tcp/$host/$port pseudo device which covers almost all use cases of Netcat just in case your machine has no Netcat installed. I still don't unde

• zaik 5y ago
  Are you sure this is a Bash feature and not some kernel module?
  • FreeFull 5y ago
    It definitely is a bash feature. From the bash manpage: Bash handles several filenames specially when they are used in redirections, as described in the following table. If the operating system on which bash is running provides these spe‐ cial files, bash will use them; otherwise it will emulate them internally with the behavior described below. /dev/fd/fd If fd is a valid integer, file descriptor fd is duplicated. /dev/stdin File descriptor 0 is duplicated. /dev/stdout File descriptor 1 is duplicated. /dev/stderr File descriptor 2 is duplicated. /dev/tcp/host/port If host is a valid hostname or Internet address, and port is an integer port number or service name, bash attempts to open the corresponding TCP socket. /dev/udp/host/port If host is a valid hostname or Internet address, and port is an integer port number or service name, bash attempts to open the corresponding UDP socket.
    • gnu8 5y ago
      It just seems confusing that bash is using the /dev namespace for this feature. Are there circumstances where /dev/tcp/host/port might be provided by the operating system and provide the same functionality? Or is that just saying bash will stay out of the way if you are trying to access special files in /dev if they really exist?
      • dpedu 5y ago
        Unless the operating system decides to use bash to access some device, it's fine. Nothing besides bash can see these. They're not really there. It's a mirage created by bash.
        • numpad0 5y ago
          That’s the problem.
          • pepetf 5y ago
            no such thing as chill or etc, monex doesnt matter
      • FreeFull 5y ago
        /dev/std{in,out,err} are provided by Linux, and bash does stay out of the way there. I'm not aware of anything that provides /dev/tcp/host/port, although I think Plan 9 might have something similar. If the file happens to exist, bash will use the file rather than its own special functionality.
      • zamadatix 5y ago
        The old TLI/XTI alternatives to BSD sockets (pre when BSD sockets were standardized into POSIX sockets) back in the System V days provided this path/socket connection format. For a modern holdover these are still available in Solaris.
• tyingq 5y ago
  Good for clients, but bash can't do a listen socket. Gawk can, though it's pretty limited.
• AnIdiotOnTheNet 5y ago
  Because Linux didn't copy everything from Plan9. Unfortunately.
  • yjftsjthsd-h 5y ago
    I wonder how hard it would be to write kernel modules to fix that.
  • anthk 5y ago
    aux/listen on Linux world? What's next? purging NFS for 9p and wireguard?
    • tyingq 5y ago
      WSL uses 9p, though it seems to be a bit slow in that area.