如何设置php实现session定期自动清理

[root@hz scripts]# grep "session.save_path = " /usr/local/php/lib/php.ini 
;   session.save_path = "N;/path" 
;   session.save_path = "N;MODE;/path" 
;session.save_path = "/tmp" 
session.save_path = "2;/tmp/session" 
[root@hz ~]# cat /byrd/script/Cleartmpsen.sh 
#!/bin/bash 
# Version:1.0 
# Author:Byrd 
# Site:www.t4x.org 
# Contact:root#t4x.org 
# This is script will clear php session before 3 hours. 
i="0 1 2 3 4 5 6 7 8 9 a b c d e f" 
for byrd in $i; 
do 
  for x in $i; 
  do 
    mkdir -p /tmp/session/$byrd/$x; 
  done; 
done 
chown -R bywww:bywww /tmp/session 
chmod -R 1777 /tmp/session 
find /tmp/session -amin +180 -exec rm -rf {} ＼; 
if [ `grep 'session.save_path =' /usr/local/php/lib/php.ini | wc -l` -eq 3 ];then 
  sed -i 's#;session.save_path = "/tmp"#;session.save_path = "/tmp"＼nsession.save_path = "2;/tmp/session"#g' /usr/local/php/lib/php.ini 
else 
  exit 1 
fi 


定时任务： 
[root@hz scripts]# echo '#This is a config php session BY:BYRD AT:2015-11-12' >>/var/spool/cron/root 
[root@hz scripts]# echo '0 3 * * 0 /bin/bash /byrd/scripts/spehspsion.sh >/dev/null 2>&1' >>/var/spool/cron/root