Bash script to connect to open port, send request, read response

Question

I have a service running on localhost:port. In a bash script I want to connect to this port, send a request, and read back the response - essentially automating a telnet session. What's the best way of doing this? Am looking at /dev/tcp, netcat or telnet/expect.

Thanks

Joey · Accepted Answer · 2009-12-02 11:38:12Z

1

netcat should pretty much be able to do what you want.

answered Dec 2, 2009 at 11:38

Joey

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antik · Accepted Answer · 2009-12-02 11:39:02Z

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Expect is great if you can get it to do what you'd like: it's easy to pickup and work with just by reading the man page.

answered Dec 2, 2009 at 11:39

antik

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Brian Agnew · Accepted Answer · 2009-12-02 11:39:28Z

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Expect was built to do this precise task. It will not only handle the client/server dialog, but also the scenarios of timeouts, disconnects etc. It's available in multiple implementations (Perl and Tcl are two off the top of my head) so you can choose one to fit in with your current standards and environment.

answered Dec 2, 2009 at 11:39

Brian Agnew

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2 Comments

Richard H Over a year ago

As far as I can tell with expect though, is that it actually expects a particular response, e.g "Password". In this case, I don't know what I'll be getting back - I just want to read whatever comes back.

Brian Agnew Over a year ago

I think you should be able to wildcard this

t0mm13b · Accepted Answer · 2009-12-02 11:48:19Z

0

I believe you can automate this, I recall seeing the telnet commands (using Ctrl+M markers for simulating a carriage return) and putting these commands into a text file and issuing

telnet somehost

And the output was sent out to the standard output (your terminal) which can then be captured.

Hope this helps, Best regards, Tom.

P.S: Here's a link to something found using this on the command line here.

edited Dec 2, 2009 at 11:48

answered Dec 2, 2009 at 11:40

t0mm13b

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1 Comment

t0mm13b Over a year ago

As mentioned by antik & Brian Agnew, it seems expect is the much easier solution. :)

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