Auto exit Telnet command back to prompt without human intervention ^] quit close exit code 1

Question

I\'m running telnet command on a host for a given port (which is open), it returns 0 (success).

For trying telnet manually, I type the following comman

Answer 1

Here is the clean way to do it

echo -n | telnet `hostname` 2878

For more info on this behavior see this link

Answer 2

Without using Expect, I guess using the HERE document (<

[vagrant@myvagrant /tmp] $ telnet_result=$(telnet `hostname` 2878 <<GIGA
echo ^]
echo close
GIGA
); echo $telnet_result | grep "Escape character is '^]'"; echo $?
Connection closed by foreign host.
 Escape character is '^]'.
0
[vagrant@myvagrant /tmp] $ 

and for a bad/invalid/non-open port, the same gives 1 (as expected).

[vagrant@myvagrant /tmp] $ telnet_result=$(telnet `hostname` 287811111 <<GIGA
echo ^]
echo close
GIGA
); echo $telnet_result | grep "Escape character is '^]'"; echo $?
telnet: connect to address 127.0.0.1: Connection refused
1
[vagrant@myvagrant /tmp] $ 

Answer 3

A slight improvement to the answer provided by Matthew above which allows you to use it inside shell scripts:

$ echo -e '\x1dclose\x0d' | telnet google.com 80
Connected to google.com.
Escape character is '^]'.

telnet> close
Connection closed.
$ echo $?
0

Answer 4

╭─ ~
╰» echo "^]close^M" | telnet localhost 22; echo $?
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.

telnet> close
Connection closed.
0

To enter the ^] and ^M characters, press ctrl+v ctrt+] and ctrl+v ctrl+m respectively.

Answer 5

You may need other linux package like expect to achieve what you want.