【原创】修改WIFI保持连接脚本
项目中用到wifi，由于无线网络的不稳定性，可能会造成wifi的掉线，这就需要在程序中判断网络的是否联通，并且能在断线后继续搜寻无线网络并重新连接。
并且因为wifi连接有许多现成的工具，所以在这里就利用shell脚本来实现此功能。
本篇博客主要是记录我修改此脚本到当前项目的记录，包含shell脚本的一些用法和wifi连接工具的用法：
一、初始化函数init_var
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init_var() { #until [ -d $SYSFS ] ; do sleep 1; done #find the first useable wifi card local wifi_dev #定义局部变量wifi_dev wifi_dev=$(iwconfig 2>&1
| grep -v "no wireless"
) #查看当前设备有的无线设备，grep -v 指的是去除no wireless这一行 while
true; do #无限循环 if
[ -z "$wifi_dev"
]; then #判断wifi_dev字符串是否为空 是空则执行下面的命令 sleep 3 wifi_dev=$(iwconfig 2>&1
| grep -v "no wireless"
) else
#不为空 获取当前wifi设备名 IFACE=$(iwconfig 2>&1
| grep -v -n "no wireless"
| awk ‘{print $1}‘
| awk -F: ‘{print $2}‘
| grep 0) break fi done # support only pc run dhclient which dhclient #判断 dhclient工具是否存在 if
[ $? -ne 0
]; then RUN_PC=0 else RUN_PC=1 fi if
[ "$RUN_PC"
= "0" ] ; then DHCP_CLIENT=udhcpc DHCP_CLIENT_OPT=" -i " PING_KEYWORD=round-trip DHCP_WAIT_TIMES=5 else DHCP_CLIENT=dhclient PING_KEYWORD=rtt DHCP_WAIT_TIMES=5 rm -f /var/lib/dhclient/dhclient.leases fi tmpfsloc=$(mount | grep tmpfs | awk ‘{print $3}‘
| head -n 1) loc=${tmpfsloc:-/dev} WPA_CONFIGFILE=$loc/wpa_supplicant.conf echo dhcp client app is
$DHCP_CLIENT #打印相关信息 echo ping key words is
$PING_KEYWORD echo ESSID is
$CONF_ESSID echo interface is
$IFACE echo run mode is
$RUN_MODE} |
二、主循环程序如下
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while
[ -d $SYSFS ] ; do network_connect if
[ $? -ne 0
]; then echo --INFO--:network is
disconnected? try
to reconnect ifconfig $IFACE 0.0.0.0 setup_wifi fi sleep $CHECK_PERIODdone |
network_connect是一个函数，其主要功能是判断网络是否联通，然后是一个判断语句，如过network_connect不成功（返回的不是0），
则执行setup_wifi函数，此函数的主要功能重新设置并连接wifi。如果网络联通则睡眠CHECK_PERIOD秒后再重新判断连接是否正常。
三、判断网络是否连接函数network_connect
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network_connect() { #get ip first ifconfig $IFACE | grep -q "inet addr"
#判断当前是否有IP地址 if
[ $? -ne 0
]; then echo can\‘t find IP return
1 fi #get default gateway route | grep -q default | awk ‘{print $2}‘
#获取当前连接路由的网关地址 if
[ $? -ne 0
]; then echo can\‘t get default gatway return
1 else SERVER_IP=$(route | grep default | awk ‘{print $2}‘) fi if
[ -z $SERVER_IP ]; then echo did not
get server ip by route, server_ip=$SERVER_IP return
1 fi if
! ping -c $PING_RETRY_COUNT -q $SERVER_IP | grep -q $PING_KEYWORD; then #利用ping命令查看网络是否联通 echo ping $SERVER_IP failed return
1 fi} |
四、加入路由函数setup_wifi
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setup_wifi() { ifconfig $IFACE down ifconfig $IFACE up #将无线网卡重启 echo start wireless scanning local count=0 until [ $count -ge 3
] ; do get_auth_mode #获取AP加密方式等信息，如果未找到指定AP，将会返回1 if
[ $? -ne 0
]; then echo "AP $CONF_ESSID not found, sleeping..."; sleep 5; let ‘count=count+1‘; else break
#找到后返回 fi done #scan ok if
[ $count -lt 3
] ; then if
[ "$RUN_MODE"
= "debug" ] ; then set_wifi_mode return
0 fi fi local index if
[ $count -lt 3
] ; then echo APs list: ${mac_ary[*]} #打印获取后的同名AP列表 echo signal list: ${siglevel_ary[*]} echo sort index: ${sort_ary[*]} for(( i =
1; i <=
$AP_COUNT; i++)) #下面的功能是找到最大信号的那个AP 并加入到其中，如果加入不成功，依次加次强的那个 do index=${sort_ary[i]} #the first is most signal bssid=${mac_ary[index]} echo try
AP: ${ssid_name_ary[index]} $bssid set_wifi_mode #该函数是设置wifi模式，并调用WPA_CONFIGFILE工具，连接AP if
[ $? -ne 0
]; then echo association with $bssid failed else echo association with $bssid OK break fi done fi} |
五、搜寻指定AP，并获得AP加密方式函数get_auth_mode
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get_auth_mode() { local grep_expr found local ad_hoc_grep iwlist_log=$(iwlist $IFACE scanning) #扫描所有AP信息 grep_expr="ESSID:\"$CONF_ESSID\"" ad_hoc_grep="Mode:$ADHOC_MODE" local start_line start_line=$(printf "%s \n"
"$iwlist_log" | grep -n $grep_expr | awk -F: ‘{print $1}‘)#找到符合指定AP名的行 AP_COUNT=$(echo $start_line | wc -w) #判断有几行 echo total ap number is
$AP_COUNT #有几行就说明有几个同名AP # if AP_COUNT > 0 if
[ $AP_COUNT -gt 0
]; then #如果大于0就说明找到指定AP found=true else return
1 fi start_line=$(printf "%s \n"
"$iwlist_log" | grep $grep_expr -B 2
| grep Cell | awk ‘{print $2}‘) #获得全部指定AP名的Cell local i cell for((i =
1; i <=
$AP_COUNT; i++
)) #将每个同名AP分离出来 并存到数组内 do cell=$(echo $start_line | awk ‘{print $(‘$i‘)}‘) get_ssid_str $cell $i #根据Cell编号，获取每个同名AP的加密信息 done #suppose all APs used the same encryption settings, for supporting roaming ssid_str=${ssid_str_ary[1]} #数组内第一个AP就是同名AP中信号最强的 Encryption=$(printf "%s \n"
"$ssid_str" | grep Encryption | awk -F: ‘{print $2}‘)#下面是获取其加密类型 Auth_Suite=$(printf "%s \n"
"$ssid_str" | grep "Authentication Suites"
| awk ‘{print $5}‘) Group_cipher=$(printf "%s \n"
"$ssid_str" | grep "Group Cipher"
| head -n 1
| awk ‘{print $4}‘) echo --INFO--:Group_cipher=$Group_cipher #Pair_ciper=$(printf "%s \n" "$ssid_str" | grep "Pairwise Ciphers" | awk ‘{print $5}‘) if
[ "$Auth_Suite"
= "802.1X" ]; then #转化为wpa_supplicant对应的加密类型 #Auth_Suite is PSK or 802.1X echo didn\‘t support WPA Enterprise, Authentication Suites is
$Auth_Suite return
1 fi if
[ "$Group_cipher"
= "CCMP" -o "$Group_cipher"
= "TKIP" ]; then EncrypType=$Group_cipher fi AuthMode=WEP if
[ "$Encryption"
= "off" ]; then AuthMode= return
0 fi if
echo $ssid_str | grep -q "802.11i/WPA2"
; then AuthMode=WPA2 return
0 fi if
echo $ssid_str | grep -q "WPA Version"
; then AuthMode=WPA return
0 fi return
0 } |
六、加入AP函数set_wifi_mode
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set_wifi_mode() { echo auth mode is
$AuthMode if
[ "$RUN_MODE"
= "debug" ] ; then killall $DHCP_CLIENT killall wpa_supplicant sleep 5 ifconfig $IFACE up sleep 2 #iwconfig $IFACE key off iwconfig $IFACE mode $ADHOC_MODE sleep 2 iwconfig $IFACE essid "$DEBUG_CONF_ESSID" ifconfig $IFACE $DEBUG_FIX_IP return fi if
[ "$AuthMode"
= "WEP" ] ; then #判断加密类型 生成wpa_supplicant所需的.conf文件 local pref if
[ "$WEP_KEY_TYPE"
= "char" ] ; then pref="s:" fi iwconfig $IFACE key open
$pref$PASSWORD [$WEP_KEYINDEX] iwconfig $IFACE essid "$CONF_ESSID" echo try
"open" Authentication mode sleep 5 name=$(iwconfig $IFACE | head -1
| awk -F\" ‘{print $2}‘) if
[ "$name"
!= "$CONF_ESSID" ];then echo "open"
Authentication mode failed, try
shard mode iwconfig $IFACE key restricted $pref$PASSWORD [$WEP_KEYINDEX] iwconfig $IFACE essid "$CONF_ESSID" fi elif
[ "$AuthMode"
= "WPA2" -o "$AuthMode"
= "WPA" ] ; then killall wpa_supplicant write_wpa_config #此函数生产.conf文件 sleep 2 ifconfig $IFACE up sleep 2 wpa_supplicant -i $IFACE -B -c $WPA_CONFIGFILE #利用wpa_supplicant工具加AP #wait wpa config, associ sleep 10 else iwconfig $IFACE key off iwconfig $IFACE essid "$CONF_ESSID" fi if
[ "$AuthMode"
!= "WPA2" -a "$AuthMode"
!= "WPA" ]; then if
[ "$SET_MODE"
= "yes" ] ; then if
[ "$RUN_MODE"
= "debug" ] ; then killall $DHCP_CLIENT killall wpa_supplicant sleep 2 ifconfig $IFACE up sleep 2 fi iwconfig $IFACE mode $ADHOC_MODE else iwconfig $IFACE mode $DEFAULT_MODE fi fi #check if successed #判断是否加入成功 ssidname=$(iwconfig $IFACE | grep $IFACE | awk -F: ‘{print $2}‘
| awk ‘{print $1}‘) cur_bssid=$(iwconfig $IFACE | grep "Access Point:"
| awk ‘{print $6}‘) cur_mode=$(iwconfig $IFACE | grep Mode | awk -F: ‘{print $2}‘
| awk ‘{print $1}‘) echo $ssidname $cur_bssid $cur_mode if
[ "$ssidname"
!= "\"$CONF_ESSID\"" -o "$bssid"
!= "$cur_bssid" \ -o "$cur_mode"
!= "$DEFAULT_MODE" ]; then #fail return
1 fi if
[ -z $FIX_IP ] ; then dhcp_pc dhcp_ok=$(ifconfig $IFACE | grep "inet addr"
| awk ‘{print $1}‘) if
[ -z $dhcp_ok ]; then return
1 fi else ifconfig $IFACE $FIX_IP fi if
[ "$RUN_MODE"
!= "debug" ] ; then route add default gateway $SERVER_IP $IFACE fi return
0} |
七、生产wpa_supplicant所需.conf文件函数
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write_wpa_config() { #init wpa_supplicant.conf file if
[ -f $WPA_CONFIGFILE ]; then rm -f $WPA_CONFIGFILE fi cat >$WPA_CONFIGFILE<<-EOF ctrl_interface=/var/run/wpa_supplicant network={ ssid="$CONF_ESSID" bssid=$bssid scan_ssid=1 key_mgmt=WPA-PSK proto=$AuthMode pairwise=$EncrypType group=$EncrypType psk="$PASSWORD" } EOF} |
至此，此脚本全部结束，这个脚本的最好处在于支持wifi信号的漫游。
【原创】修改WIFI保持连接脚本,布布扣,bubuko.com
原文：http://www.cnblogs.com/M-Bing/p/3647268.html