iwscan

#!/bin/sh
##
## List wireless access points in line-by-line format
## Copyright (c) 2013-2022 SATOH Fumiyasu @ OSSTech Corp., Japan
##
## License: GNU General Public License version 3
##

set -u

if [ X"`id |sed 's/).*//;s/.*(//'`" != X"root" ]; then
  exec sudo -u root "$0" ${1+"$@"}
  exit $?
fi

if [ "${1+set}" ]; then
  if="$1"; shift
else
  if=$(iwconfig 2>/dev/null|sed -n '/^[a-z][a-z0-9]* *IEEE 802\.11/ { s/ .*//; p; q; }')
fi

iwlist "$if" scan \
|sed 's/^\( *Cell\) \([0-9]*\) - /\1\t\2\n/;s/^ *\([^:=]*\)[:=] */\1\t/' \
|awk '
  BEGIN {
    FS = "\t"
  }
  info["Channel"] > 0 && ($1 == "Cell" || $1 == "") {
    if (info["Encryption"] == "?") {
      info["Encryption"] =  "WEP?"
  }
    printf "%3d %-5s %-8s %-42s %s\n",
      info["Channel"],
      info["Quality"],
      info["Mode"],
      info["ESSID"],
      info["Encryption"],
      ""
      ;
    delete info
    info["Encryption"] = "-"
  }
  {
    info[$1] = $2
    if ($1 == "Quality") {
      sub(/ .*/, "", info[$1])
    }
  }
  $1 == "Encryption key" && $2 == "on" {
    info["Encryption"] = "?"
  }
  $1 == "IE" && $2 ~ /WPA/ {
    enc = $2
    sub(/^IEEE 802\.11i\//, "", enc)
    sub(/ Version /, " v", enc)
    info["Encryption"] = (info["Encryption"] == "?") ?  "" : info["Encryption"] ","
    info["Encryption"] = info["Encryption"] enc
  }
' \
|sort -n \
;