下面哪条命令可用来确保文件“myfile”存在 。

A . typemyfile B . type-qmyfile C . filemyfile D . whAtismyfile

A . COPYMYFILE.PRGPRN B . COPYMYFILE.PRG>PRN C . COPYPRNMYFILE.PRG D . COPYPRN>MYFILE.PRG

A . A、Cp －wmyDirmyfileDir2 B . B、Cp -imyDirmyfileDir2 C . C、Cp myDirmyfileDir2 D . D、Cp -vmyDirmyfileDir2

A . cp file1/dev/null B . touch file1 C . create file1 D . mkfile file1

A . A、Tree B . B、Attrib C . C、SYS D . D、DiskCopy

A . find/-typed\（-perm-4000-o-perm-2000\）–print B . find/-typef\（-perm-4000-a-perm-2000\）–print C . find/-typef\（-perm-4000-o-perm-2000\）–print D . find/-nouser-o-nogroup–print

A . cdhls B . cdhch C . cdhrm D . cdhver

A . A.Application_OnEnd B . B.Application_OnStart C . C.Session_OnEnd D . D.Sever_OnStart

A . imagex.exe/mountanswer.xml/verify B . imagex.exe/appendanswer.xml/check C . sysprep.exe/generalize/oobe/unattend：answer.xml D . sysprep.exe/reboot/audit/unattend：answer.xml

A . cdhls B . cdhch C . cdhrm D . cdhver

A . newuser B . useradd C . mkuser D . usercfg

A . FORMAT B . COPY C . DIR D . XCOPY

A . ldd B . ldso C . modprobe D . ldconfig

A . vi B . ed C . crontab D . edit

A . ACAD.CFG B . ACAD.INI C . ACAD.PGP D . ACAD.ACS

A . RnlcDcmDbgUeCtxtRelCmd B . RnlcDcmDbgCloseAutoFailRsp C . RnlcDcmDbgCloseAutoRsp D . SerReqSaeRelFalMsg

A . cp myfile /dev/null B . touch myfile C . create myfile D . mkfile myfile

A . display acl config all B . display access-list all C . display ip access-list all D . display access-list link

A . tar B . cpio C . umask D . backu

A．A.LST RRU B．B.DSP BRD C．C.DSP CELL D．D.DSP BRDMFRINFO

A．Tree B．Attrib C．SYS D．DiskCopy

A．tar -cvf myfile.txt myfile.txt.tar.gz B．tar -zcvf myfile.txt myfile.txt.tar.gz C．tar -cvf myfile.txt.tar.gz myfile.txt D．tar -zcvf myfile.txt.tar.gz myfile.txt