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In Ubuntu 11.04 I used InSSIDer to scan the available APs and sort them by signal strength.

Unfortunately the program seems to be broken in Ubuntu 11.10, and

iwlist wlan0 scan

doesn't return anything meaningful.

What options do I have to scan for available Wireless Access Point, possibly with a GUI?

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1  
Ubuntu release? Hardware? Environment? "anything meaningful"? Should I have to install 11.04 and InSSIDer to find out what behaviour you're looking for? What does "seems to be broken" really mean? Please help us help you by including information in your questions. "Options"? Try Network Manager. You should find its icon in the top row. –  waltinator Nov 6 '11 at 23:13
    
If you read it more carefully everything is already there. I use ubuntu 11.10, and inssider doesn't launch at all. I use intel wifi. I want to list all the available networks, sorted by strength. –  Mascarpone Nov 7 '11 at 16:21
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sudo iwlist wlan0 scanning | egrep 'Cell |Encryption|Quality|Last beacon|ESSID' should help. –  waltinator Nov 7 '11 at 19:30
    
great thanks!!! if you post it as answer I will accept it! –  Mascarpone Nov 7 '11 at 19:57
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2 Answers

up vote 7 down vote accepted

sudo iwlist wlan0 scanning | egrep 'Cell |Encryption|Quality|Last beacon|ESSID' should help.

It's the combination of sudo (run as root, do privileged operations), iwlist wlan0 scanning (produce some output on STDOUT), the pipe symbol "|" (connecting STDOUT of the command(s) to the left to the STDIN of the process on the right), and an egrep command with a "single quoted" (to prevent the shell from interpreting the "|" characters) Regular Expression to filter STDIN. See man bash, man sudo, man iwlist, man egrep, and man re_format for details.

ALWAYS do man whatever (as above) BEFORE you execute a command string from someone else. Self-education is much safer than blind trust.

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Could you please include an explanation of that command? –  N.N. Nov 7 '11 at 21:31
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Could you please include the explanation in your question instead so that others can find it easier and benefit from it. Reason I asked for an explanation is to make your answer as complete as possible. –  N.N. Nov 8 '11 at 7:13
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nm-tool | grep "Freq.*Strength" | sed -ne "s|\(.*Strength \([0-9]\+\).*\)|\2}\1|p" | sort -n -r
  1. Use output of nm-tool to get list of Wireless Access Points
  2. Filter to get access points only
  3. Use sed to append signal level in front of each line
  4. sort output as numbers in reverse order (largest first)

nm-tool is part of "network-manager" package that is obviously installed in a typical Ubuntu system.

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