:: Re: [DNG] Systemd Shims
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Autore: Edward Bartolo
Data:  
To: Steve Litt
CC: dng
Oggetto: Re: [DNG] Systemd Shims
At long last, the backend runs without the frontend having for it to
finish as I wished. This got rid of frontend hangs.



On 21/08/2015, Steve Litt <slitt@???> wrote:
> On Fri, 21 Aug 2015 06:47:13 +0100
> Edward Bartolo <edbarx@???> wrote:
>
>> Parsing headaches:
>>
>> I have this chunk of data retrieved from the backend which I need to
>> parse *reliably*. The goal is to read the SSID and the corresponsing
>> signal strength.
>>
>> How should I proceed. This part of code will be done from within
>> Lazarus. Please, be informed that Lazarus generated GUI uses GTK* as a
>> base. The executable can is also statically built which means an
>> increased portability. Executables are about 3 MB. In the past I have
>> written such applications that dwarf what I am doing and still the
>> size is small.
>>
>> Here is what I want to parse:
>>
>> root@edbarx-pc:/home/edbarx# iwlist wlan0 scan | grep -B 4 ESSID
>>
>> <<<<<<<<<
>>                     Channel:1
>>                     Frequency:2.412 GHz (Channel 1)
>>                     Quality=70/70  Signal level=-34 dBm
>>                     Encryption key:on
>>                     ESSID:"EB-TP-LNK67"
>> --
>>                     Channel:6
>>                     Frequency:2.437 GHz (Channel 6)
>>                     Quality=24/70  Signal level=-86 dBm
>>                     Encryption key:on
>>                     ESSID:"TNCAPA0332D"
>> --
>>                     Channel:11
>>                     Frequency:2.462 GHz (Channel 11)
>>                     Quality=30/70  Signal level=-80 dBm
>>                     Encryption key:on
>>                     ESSID:"Home WiFi"

>> >>>>>>>>>>>>>>>
>
> :-)
>
> Hi Edward,
>
> At this point you're a lot more knowledgeable on this situation than I,
> but I'll give you an opinion. If this problem were any more complex,
> I'd suggest spawning awk, but it looks to me like as long as you can
> get these lines into Lazarus, I think you're golden.
>
> Please refer to http://dpaste.com/0FZE769 ...
>
> First thing: By using grep -B, you're throwing away some information
> you need: Specifically, encryption type. I'd recommend you pull *all*
> the output from iwscan $device scanning into a Turbo Pascal (you know
> what I mean) file linked into your Lazarus program,
> except "^\s+IE: Unknown".
>
> It's pretty easy to parse:
>
> * Throw away anything beginning with "^\s*IE: Unknown"
> * Throw away ^$device\s+Scan completed
> * Every ^\s*Cell \d starts a new record, record the cell number
>
> Every line is one of the following:
>
> 1. ^$device\s+Scan Completed
> 2. ^\s+Cell
> 3. ^\s+IE: Unknown
> 4. ^\s+\S.*:
> 5. ^\s+\S.*=
> 6. Everything else
>
> #3 can be avoided by having your original command be the following:
>
> root@edbarx-pc:/home/edbarx# iwlist wlan0 scan | grep -v "^\s+IE:
> Unknown:"
>
> #4 are the key/value pairs comprising most of what you need
>
> #6 are all additional information appended to the #4 item preceding
> them. So you need a somewhat stateful algorithm. You may or may not
> need a Group Cipher, Pairwise Ciphers, and/or Authentication Suites. If
> you don't need those three things, I think you can throw away all #6.
>
> #2 separates records
> #5 is the signal quality/level line. Give it its own subroutine.
> #1 gets thrown out
>
> Anyway, you definitely need to capture the encryption type, and by
> using your grep -B4 ESSID you're throwing that away. NetworkManager and
> Wicd both show encryption type on the ESSID list, and when I use
> either of this, I want to know which ones are WPA as opposed to
> (eeeuuu) WEP and which are (be very careful) unencrypted.
>
> HTH,
>
> Steve
>
> Steve Litt
> August 2015 featured book: Troubleshooting: Just the Facts
> http://www.troubleshooters.com/tjust
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