Testing telnet connections in a script

01-12-2007

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Testing telnet connections in a script

Hi,

I am trying to figure out how to test to see if a server is accepting telnet connections via a script.

I have several remote MPE servers that are set in single user mode (and hence not accepting telnet connections), for their backups, I want to try and automate a test (from a unix server), to see if telnet connections are available and hence if the servers are still in single user mode.

Hmm ... not sure how clear that was ... I basically want to do something like this:

while true
do
telnet <server_name> > richtmp &
echo $! > richtmp.PID
***some kind of grep thing on 'richtmp' to see if the connection worked***
kill `cat richtmp.PID`
sleep 60
done

.... but more elegantly. Is there an option to the telnet command that will do this?

many thanks,

Richard

dikiee

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CON(1) General Commands Manual CON(1) NAME
con, telnet, cu, rx, xms, xmr - remote login, execution, and XMODEM file transfer SYNOPSIS
con [ -dCrvs ] [ -l [ remuser ] ] [ -c cmd ] [net!]machine telnet [ -dCrn ] [net!]machine cu number rx [ -n ] [net!]machine [ command-word ... ] xms file xmr file DESCRIPTION
Con connects to the computer whose network address is net!machine and logs in if possible. With no options, the account name used on the remote system is the same as that on the local system. Standard input and output go to the local machine. Options are: -l with an argument causes remuser to be used as the account name on the remote system. Without an argument this option disables auto- matic login and a normal login session ensues. -C forces cooked mode, that is, local echo. -c runs cmd as if it had been typed as a command from the escape mode. This is used by cu. -v (verbose mode) causes information about connection attempts to be output to standard error. This can be useful when trying to debug network connectivity. -d causes debugging information to be output to standard error. -r suppresses printing of any carriage return followed by a new line. This is useful since carriage return is a printable character in Plan 9. -s strips received characters to 7 bits to forestall misinterpretation of ASCII with parity as UTF. The control- character is a local escape. It prompts with the local machine name and >>>. Legitimate responses to the prompt are i Send a quit [sic] signal to the remote machine. q Exit. b Send a break. . Return from the escape. !cmd Run the command with the network connection as its standard input and standard output. Standard error will go to the screen. This is useful for transmitting and receiving files over the connections using programs such as xms. Telnet is similar to con, but uses the telnet protocol to communicate with the remote machine. If standard input is a file or a pipe, the -n option causes telnet not to hang up the connection when it receives EOF on its standard input; instead it waits for the remote end to hang up. It shares con's -C, -d, and -r options. Cu is a shell script that uses telco(4) and con to connect to a machine via a modem. If the machine is equipped with a local modem, it is used. Otherwise, the call is placed through Datakit. Rx executes one shell command on the remote machine as if logged in there, but with local standard input and output. A rudimentary shell environment is provided. If the target is a Plan 9 machine, $service there will be rx. Network addresses for both con and rx have the form network!machine. Supported networks are those listed in /net. The commands xms and xmr respectively send and receive a single file using the XMODEM protocol. They use standard input and standard out- put for communication and are intended for use with con. EXAMPLES
rx kremvax cat file1 >file2 Copy remote file1 to local file2. rx kremvax cat file1 '>file2' Copy remote file1 to remote file2. eqn paper | rx kremvax troff -ms | rx deepthought lp Parallel processing: do each stage of a pipeline on a different machine. SOURCE
/sys/src/cmd/con for con, xms, and xmr. /sys/src/cmd/ip for telnet. /rc/bin/cu BUGS
Under rx, a program that should behave specially towards terminals may not: e.g., remote shells will not prompt. Also under rx, the remote standard error and standard output are combined and go inseparably to the local standard output. CON(1)

Shell Programming and Scripting

Testing telnet connections in a script

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