Command timeout with Shell Script

[robas]

Hi all

My intention is to perform a telnet command with a timeout feature.
I'm trying to implement it through a shell script which:
1. Starts a counter
2. Issue the telnet command (in background)
3. Checks if the timeout was reached or the telnet command finished (while loop)
4. If timeout was reached, kills the telnet command
5. If the command executed well, stops the counter
6. Calculates the time difference

I started scripting, but faced a problem with the return code from the telnet command.

The code: pastebin . com / HumprZUD

Thanks guys.

[robas]

Any hint on how to implement a timeout ??

Tks

[atreyu]

Let me get it straight: so you want to run a telnet job in the background, and after some specified internal, kill the telnet job, if still running?

[robas]

Exactly, but I need to get the result from the telnet. If the server refused the connection or not.

[atreyu]

Why do you need to run it in the background, though? Can you give examples of what might normally be returned by your telnet command?

Are you just testing if telnet is running? Is is that you are testing that the ip might be down, or that the port is closed, or that the service is down? or something else?

You can verify that the port is open with:
nmap -n -p 23 <TELNET_SERVER_IP>

Edit: maybe a solution for you is here

[robas]

Let me put some context here
The intention behind all of this is to get the IP/Port latency.

I expect the line "Escape character is '^]'.", like below:

telemoni@scotipandora001:/tmp> telnet 10.27.32.34 1828

telemoni@scotipandora001:/tmp> telnet 10.27.32.34 1828
Trying 10.27.32.34...
Connected to 10.27.32.34.
Escape character is '^]'.
Connection closed by foreign host.
telemoni@scotipandora001:/tmp>

I'm running it in background in order to don't get stucked on the telnet and to run the timer to check the timeout (in some cases the telnet delays a LOT).

Do it clarify a little bit? Hope so

ps: Hmm, let me check the suggested alternative with netcat.. Thanks !!

[robas]

Nmap is the easiest way to go
I forgot nmap's output includes the latency...

nmap --host-timeout 15000 10.27.32.34 -p 1830 | awk {'print $11'} | tail -1

Thanks atreyu

Why do you need to run it in the background, though? Can you give examples of what might normally be returned by your telnet command?

Are you just testing if telnet is running? Is is that you are testing that the ip might be down, or that the port is closed, or that the service is down? or something else?

You can verify that the port is open with:
nmap -n -p 23 <TELNET_SERVER_IP>

[atreyu]

I forgot nmap's output includes the latency...

me too! np