Pi to Pi connectivity

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1

Is it possible to connect two RPi’s via network or wifi only (i.e. no particle pi)??
If it is… how would I go about sending a text file from one pi to another?

2

Hey @Denver42165, thanks for bringing your question to the forum.

The short answer is yes. Once both Pis are on a network, they are connected. The command to use is secure network copy - scp - which has the following syntax:
scp <source> <destination>

To copy a file from B to A while logged into B:
scp /path/to/file username@a:/path/to/destination

To copy a file from B to A while logged into A:
scp username@b:/path/to/file /path/to/destination

where a and b are the Pis hostnames or local IP addresses

Here’s a concrete example; I have two Pis that I develop on:

  • A Raspberry Pi 3 B that I call devpi3b
  • A Raspberry Pi Zero W, called devpi0w

Lets pretend there’s a data file (data) in the user-directory of devpi0w that I want to fetch, and I’m working on devpi3b I can execute:
scp pi@devpi0w.local:/home/pi/data.txt /home/pi/data.txt
Here I’m using the hostname of the Pis, followed by .local - this will usually work for DHCP routers. If you must/want, you can use the actual IP address. By default, the hostname when using Raspbian is raspberrypi.
After executing I’ll be prompted for a security confirmation and the user’s password, then the file will copy.

Of course, this will work for any type of file - not just a text file.

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3

Thanks @Michael_R.
How would I build that into a python program?

4

Hey, @Denver42165 - To help you and anybody else looking to run a shell command from a Python script, I’ve created a new forum topic here.

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5

Thanks for your help @Michael_R. I will have to give it a go sometime this weekend.

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6

Thanks guys, I was only thinking about this over the weekend… Saved me a lot of head-scratching:slight_smile:

J

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7

@Michael_R I have tried to add the scp into a python3 script. The script works but it asks for a password. Do you have any suggestions on how to remove the password or automatically fill it out?

8

Hi @Denver42165,

You’ll need to create a public+private key pair. Here’s how

https://www.raspberrypi.org/documentation/remote-access/ssh/passwordless.md

9

Thanks @Graham. I tried that last night and it didn’t work. After reading the instructions, I realised I was doing the process wrong. I try with the instructions you have provided tonight.

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