[SOLVED] grep: Am I losing the plot?

This is typical output from 'sudo iwlist wlan0 scan'

wlan0     Scan completed :
          Cell 01 - Address: 90:5C:44:AC:70:A6
                    Channel:6
                    Frequency:2.437 GHz (Channel 6)
                    Quality=50/70  Signal level=-60 dBm  
                    Encryption key:on
                    ESSID:"VM3BE77B4"

It's clear that each entry has a Channel entry, and a Quality. I've been checking things because I have a very slow wifi issue. Mow here's my problem - these checks were within a minute of each other

pi@raspberrypi:~ $ sudo iwlist wlan0 scan |grep -c Channel
14
pi@raspberrypi:~ $ sudo iwlist wlan0 scan |grep -c Quality
9
pi@raspberrypi:~ $ sudo iwlist wlan0 scan |grep -A2 Channel
                    Channel:6
                    Frequency:2.437 GHz (Channel 6)
                    Quality=48/70  Signal level=-62 dBm  
                    Encryption key:on
--
                    Channel:9
                    Frequency:2.452 GHz (Channel 9)
                    Quality=57/70  Signal level=-53 dBm  
                    Encryption key:on
--
                    Channel:9
                    Frequency:2.452 GHz (Channel 9)
                    Quality=58/70  Signal level=-52 dBm  
                    Encryption key:on
--
                    Channel:44
                    Frequency:5.22 GHz (Channel 44)
                    Quality=55/70  Signal level=-55 dBm  
                    Encryption key:on
--
                    Channel:1
                    Frequency:2.412 GHz (Channel 1)
                    Quality=68/70  Signal level=-42 dBm  
                    Encryption key:on
--
                    Channel:36
                    Frequency:5.18 GHz (Channel 36)
                    Quality=48/70  Signal level=-62 dBm  
                    Encryption key:on
--
                    Channel:6
                    Frequency:2.437 GHz (Channel 6)
                    Quality=47/70  Signal level=-63 dBm  
                    Encryption key:on
--
                    Channel:1
                    Frequency:2.412 GHz (Channel 1)
                    Quality=43/70  Signal level=-67 dBm  
                    Encryption key:on

grep is seeing 14 Channel results, only 9 Quality results, and only 8 results on Channel when I ask for the next 2 lines

That's not a good test for grep, that output changes all the time!
Why don't you test like this:

sudo iwlist wlan0 scan > text 2>&1
grep -c Channel text
...etc...

Originally Posted by business_kid and only 8 results on Channel when I ask for the next 2 lines

x2 - notice that Channel occurs twice in each match.

Got more sanity in the wifi output so this issue disappeared. Marking it solved.

BTW average user, the grep had 'Channel:n' & '(Cannel:n )' in it, and I don't thing the second one showed

I don't understand what you mean but you can make a test:

$ sudo iwlist wlan0 scan > /tmp/IWLIST_RESULT
$ grep -c Channel /tmp/IWLIST_RESULT
16
$ grep -A2 Channel /tmp/IWLIST_RESULT | grep -c Channel
16

Yeah, here I got 34 & 34.But I went a bit further than your test, adding these lines

bash-5.0$ grep -A2 Channel /tmp/IWLIST_RESULT | grep -c (Channel
bash: syntax error near unexpected token `('
bash-5.0$ grep -A2 Channel /tmp/IWLIST_RESULT | grep -c \(Channel
17

So it appears the (Channel:n ) are being read and syntax errors ignored. That goes some was to explaining it.