（2）Linux文件和目录操作命令，

pwd

cd -/~/..

tree–a/d/f/i/L

mkdir–p/v/m

touch

ls –l/a//i/h/F

cp –r/p/d/a

mv

rm –f/r/i

rmdir -pv 仅空

ln –s

readlink -f

find path –type/name/size

文件类型bcdplfs

xargs –dn

chgrp

umask

ch/lsattr-r+ai

file

md5sum

chown

chmod