If bash command can send message to a host ?
 

I want to use bash command to send message to a host ,just like "socket "in C language.

If the bash can do this ?

As far as I know, Bash by itself can't do this, but you could look into the netcat package, which gives you an easy way to send and receive data across the network.

Bash has no builtin for this directly, however you surely can use a bash script to run a standard program like nc (netcat).
It can be configured to copy stdin -> socket -> stdout, which sounds like what you're looking for.

Bash cannot internally, but bash (or any other shell) can call a command that do it. One matching your need is "nc" (http://netcat.sourceforge.net/)

Perl would be the scripting language of choice for this task (IMO).