How to use linux shell script to realize tcp/upd Protocol Communication

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There is a special file in the linux device:

/ dev/ [tcp | upd] / host/port as long as the file is read or written, it means that the system will try to connect: host this machine, which corresponds to the port port. If the host and port are present, a socket connection is established. There will be a corresponding file under the / proc/self/fd directory.

1. Test the / dev/tcp/host/post file

[chengmo@centos5 shell] $cat / dev/pts/0lrwx- 1 chengmo chengmo 64 10-21 23:05 2-> / dev/pts/0lr-x- 1 chengmo chengmo 64 10-21 23:05 3-> / proc/22185/fdlrwx- 1 chengmo chengmo 64 10-21 23:05 8-> socket: [15067661] # File descriptor 8, a socket communication channel has been opened This is a socket channel that can read and write. Because close the channel with: "" Open [chengmo@centos5 shell] $exec 8 > &-# close the channel [chengmo@centos5 shell] $ls-l / proc/self/fd/ Total 0lrwx-1 chengmo chengmo 64 10-21 23:08 0-> / dev/pts/0lrwx- 1 chengmo chengmo 64 10-21 23:08 1-> / dev/pts/0lrwx- 1 chengmo chengmo 64 10-21 23:08 2-> / dev/pts/0lr- X-1 chengmo chengmo 64 10-21 23:08 3-> / proc/22234/fd

Read the time from the time server:

[chengmo@centos5 html] $cat&6; # sends HEAD information to socket connection cat