I'm trying to grab lines from grep and sorting them into another command, the command I'm using for grepping atm is as follows (hasn't yet been chopped enough for what I will be using it, but this gives better context):

iwlist wlan0 scanning | grep -oE '(ESSID:|Quality=|Encryption Key:).*'

Output looks like this (but will change depending on my computer's location):

Quality=64/70 Signal Level=-49dBm
Encryption key:on
Quality=61/70 Signal Level=-48 dBm
Encryption key:on
Quality=30/70 Signal Level=-71 dBm
Encryption key:on
Quality=28/70 Signal Level=-83 dBm
Encryption key:on

I want to use these lines individually for executing another command

$ssid=$(zenity --list --text "Available Networks" --list --column "ESSID" --column "Secure" --column "Signal" "$ESSID" "$ENC" "$Signal");

These are the begginings of a quickie wireless network selection prompt. $ESSID/$ENC/$Signal would be based on the output from the earlier grep, so what I need to do essentially after working the grep output a bit more to look something like this in the end after chopping it with cut/awk/sed:


(note: I get the percentage by multiplying 64 by 10 then dividing by 7; 64*10/7)

Is to apply these lines recursively for every detected ESSID into the zenity command via scripting. And to add to problems; as you may notice the grep output is in reverse order from the zenity command, so this means "Hringdu_20558" would have to go in first, and "87%" would have to go in last.

In other words in this specific scenario I need to somehow grab the third line from the grep output, and append it to the other command, then work up the previous 2 lines, and repeat this going for the third line after the line I started until there are no more lines.

In essence the final zenity command should end up looking something like this based on the above outputs:

$ssid=$(zenity --list --text "Available Networks" --list --column "ESSID" --column "Secure" --column "Signal" "Hringdu_20558" "on" "91%" "SiminnEBE932" "on" "87%" "Siminn106C46" "on" "43%" "SiminnECC63F" "on" "40%");

How can I do this? Can it be done with just basic shell scripting?

1 Answer 1


I end up with something like this:

ssid=$(iwlist wlan0 scanning |
awk -F: '
BEGIN{ printf "zenity --list --text \"Available Networks\" --list --column ESSID --column Secure --column Signal "; }
/Quality/{ split($0,x,"="); Quality = int(x[2]*100/70+.5); }
/Encryption/{ Encryption = $2; }
/ESSID/{ ESSID = $2;
         printf "%s \"%s\" \"%s%%\" ", ESSID, Encryption, Quality
}' |

Doesn't really use grep, but it does what you want.

  • This seems to mostly work, I removed the grep part too. However, it fails to set the $ssid (so if I for example run this and then run echo $ssid, it will always print the first SSID no matter what I select in the menu) If I do $ssid=$(... (instead of ssid=$(... ) it seems to try to select the proper one, but it spits out a weird "not found" error while at it.
    – Cestarian
    Aug 30, 2015 at 15:08
  • Maybe that weird behavior was because I was running it as root, hmm...
    – Cestarian
    Aug 30, 2015 at 15:20
  • removing the ` \\\n` in the find printf might help. In your example ESSID:"Siminn106C4 is missing a final ". I presume it is just a typo.
    – meuh
    Aug 30, 2015 at 15:24
  • Yeah it was just a typo. I think i was running into problems with the ssid variable probably because I was running it from a sh file, Accounting properly for that I didn't have to change anything, your example was perfect (besides the grep) this definitely gets the job done, thank you.
    – Cestarian
    Aug 30, 2015 at 15:43

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