🔧Wi-Fi Channel Tool (wifichannel)

you can think of this as a warm up exercise

WLAN Pi comes with a small CLI tool called wifichannel

This tool began as a simple conversion utility, for switching between channel numbers and centre frequencies.

Channel maths

Query wifichannel with the command

wifichannel 7

The output gives you information about channel 7

Is 2.4 GHz channel 6 recommended?

wifichannel 6

Output

Band: 2.4 GHz Channel: 6 Center freq: 2437 MHz`` Recommended: Yes

Is 6 GHz channel 17 a Preferred Scanning Channel (PSC)?

wifichannel 17

Second Tab

Band: 6 GHz Channel: 17 Center freq: 6035 MHz`` PSC: No ``Lower 6 GHz

What is the centre frequency of channel 60?

wifichannel 60

Output

Band: 5 GHz Channel: 60`` Center freq: 5300 ``MHz U-NII-2A

What channel uses center frequency 6055 MHz?

wifichannel 6055

Output

Band: 6 GHz`` Channel: 21 ``PSC: Yes Lower 6 GHz

List all channels

Display all 2.4 GHz channels:

wifichannel -2

Display all 5 GHz channels:

wifichannel -5

How would you display all 6 GHz channels?

Hint

This command will help you if you are ever in doubts:

wifichannel -h

Answer

wifichannel -6

Note the Lower 6 GHz and Upper 6 GHz channels. In Czech Republic and most of Europe, we can only use the Lower 6 GHz channels.

Filter output with Linux filters (grep)

You can filter the output of most command line utilities to make the output more efficient.

Example

How many channels in the 2.4 GHz band are 'recommended'?

First, run the command to display all 2.4 GHz channels:

wifichannel -2

You could count the lines manually, but there is no need. Computers can already do that, really fast.

Using a linux utility called grep we can filter the output to only include lines that contain "a particular string or pattern":

wifichannel -2 | grep "Recommended: Yes"

Be precise with your search terms (strings), capitalisation matters.

How many channels in the 2.4 GHz band are

Finally, we can simply count the number of lines returned by the command using word count, that command looks like this:

wifichannel -2 | grep "Recommended: Yes" | wc -l

The wc command has nothing to do with restrooms 😉 It stands for "word count" and its "l" parameter stands for lines.

Answer

3

You already knew that... right.

but... this filtering allows you to quickly get an answer from the output of command line tools.