单项选择题
The command echo $! will produce what output？（）
A. the process id of last background command B. the exit status of the last command C. the exit status of the last background command D. the process id of the current shell E. the name of the command being executed
填空题 Whatcommandwithalloptionsand/orparameterwillsendthesignalUSR1toanyexecutingprocessofprogramapache2？（）
填空题 Whichcommand（withoutoptions）wouldyouusetodisplayhowmuchspaceisavailableonallmountedpartitions？（）
单项选择题 WithXorg7.0，whatisthenameofthedefaultfontserver？（）
