获取前一天时间的SH（Z）

CurYear=`date   +%Y`  
CurMonth=`date   +%m`  
CurDay=`date   +%d`  
   
GetYear="$CurYear"  
GetMonth="$CurMonth"  
GetDay="`expr   $CurDay   -   1`"  
   
 
  if   [   "$GetDay"   -le   0   ]   ;   then      
                  GetMonth=`expr   $CurMonth   -   1`      
                  if   [   "$GetMonth"   -le   0   ]   ;   then      
                                  GetYear=`expr   $CurYear   -   1`  
                                  GetMonth=12     
                  fi      
                  case   "$GetMonth"  
                  in  
                                  1|3|5|7|8|10|12)      
                                                  GetDay=31;;  
                                  4|6|9|11)  
                                                  GetDay=30;;  
                                  2)  
                                                  if   [   `expr   "$CurYear"   %   400`   -eq   0   ]   ;   then  
                                                                  GetDay=29  
                                                  elif   [   `expr   "$CurYear"   %   4`   -eq   0   -a   `expr   "$CurYear"   %   100`   -ne   0   ]   ;   then      
                                                                  GetDay=29  
                                                  else      
                                                                  GetDay=28  
                                                  fi  
                  esac      
  fi      
  if   [   `echo   "$GetMonth"   |   wc   -m`   -ne   3   ]   ;   then     
                                GetMonth=0$GetMonth  
  fi     
  if   [   `echo   "$GetDay"   |   wc   -m`   -ne   3   ]   ;   then     
                  GetDay=0$GetDay  
  fi     
  echo  
  echo   $GetYear/$GetMonth/$GetDay  
  echo

另外，可通过DATE命令，不需自己编写脚本获取
gday=`date --date="1 days ago" +%F`
gday=`date -d="1 days ago" +%F`