Ceroc Scotland Forum - View Single Post

**El Salsero Gringo** · 10th-March-2006, 12:52 AM

Here's a question for the Linux experts:

I have a tiny PC running Debian Linux as an unattended 'box'.

it's attached to a network segment which also has a satellite transceiver; iEach host on the network that wishes to send data over the satellite link needs to telnet to the satellite unit and send a sequence of three AT commands before it can send any IP packets via the satellite.

Normally these AT commands are sent by a piece of configuration software (a kind of control panel) that would run on each PC wishing to access the WAN.

What I need to do is to create a script for the linux unit that will run automatically at startup to send the correct command sequence. By choice I'd probably use Expect because that's what it's designed for; but this Debian system is a minimalist install and probably doesn't have Expect. What else can I use, how would I write the script, and how would I make it run at startup?

One complication is that the AT commands can take up to 60 or more seconds to return - usually with "OK" but possibly with an error. If an error is returned then I need the system to wait say 60 seconds then restart the script. The system has no screen, no keyboard and no possibility of user intervention, so I'm happy for it to keep trying the command sequence until it eventually succeeds.

Clearly I'm not a Linux expert, so feel free to make as many obvious points as you wish - I'm bound to learn something.

Thanks!

10th-March-2006, 12:52 AM	#1 (permalink)
El Salsero Gringo Ceroc Teacher Join Date: Jan 2005 Location: London Posts: 4,881 Status: No Status Rep Power: 4 Rep.: 2374	Linux: automatic modem configuration Here's a question for the Linux experts: I have a tiny PC running Debian Linux as an unattended 'box'. it's attached to a network segment which also has a satellite transceiver; iEach host on the network that wishes to send data over the satellite link needs to telnet to the satellite unit and send a sequence of three AT commands before it can send any IP packets via the satellite. Normally these AT commands are sent by a piece of configuration software (a kind of control panel) that would run on each PC wishing to access the WAN. What I need to do is to create a script for the linux unit that will run automatically at startup to send the correct command sequence. By choice I'd probably use Expect because that's what it's designed for; but this Debian system is a minimalist install and probably doesn't have Expect. What else can I use, how would I write the script, and how would I make it run at startup? One complication is that the AT commands can take up to 60 or more seconds to return - usually with "OK" but possibly with an error. If an error is returned then I need the system to wait say 60 seconds then restart the script. The system has no screen, no keyboard and no possibility of user intervention, so I'm happy for it to keep trying the command sequence until it eventually succeeds. Clearly I'm not a Linux expert, so feel free to make as many obvious points as you wish - I'm bound to learn something. Thanks!