UNIX Shell循环控制—while

while循环，语法如下：

.../shell/iftest>lfelif.sh            ifeditor.sh        ifparam.sh         ifwr.shgrepif.sh          ifelif.sh          ifpwd.sh           if1.sh*ifcounter.sh       ifels.sh           ifroot.sh          if2.shifcp.sh            ifinteractive.sh   ifset.shifcp2.sh           ifmkdir.sh         iftest2.shifdirec.sh         ifmkdir2.sh        iftst.sh*