今天沒事搞了兩個虛機玩玩，但是安裝軟件的時候出現錯誤，如下：
yum提示Another app is currently holding the yum lock; waiting for it to exit...
# yum -y install vixie-cron Loaded plugins: fastestmirror, refresh-packagekit, security Existing lock /var/run/yum.pid: another copy is running as pid 25960. Another app is currently holding the yum lock; waiting for it to exit...
yum在鎖定狀態中。
已經有一個yum進程在運行了，目前使用kill殺了進程：
# kill -s 9 *****
# ps aux|grep yum
root 16744 0.0 0.0 1032 900 pts/1 S+ 09:19 0:00 grep yum
root 55960 0.0 0.0 0 0 ? Z Sep19 0:01 [yumBackend.py] <defunct>
kill不了，那怎么辦呢？
可以通過強制關掉yum進程：
#rm -f /var/run/yum.pid
然后就可以使用yum了。