4 ms·

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

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.

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.