for var in 1 2 3 4 5      (ps:或者for var in $(seq 1 5)或者for var in {1..5})
   do
        echo -n "$val   "
   done

　　for((i=0;i<10;i++))            (  ps:必須是for(( ))  )
   {
         let "val=i%2"
         if [ $val -ne 0 ]; then
             echo
 
 "${i} is a odd number"
         fi
   }

　　 while read line            # (  ps:while讀取是按行讀，常用於文本按行讀取 )
    do
        if [ "$line" -eq 5 ]; then
              echo "5"
              break
        fi
    done                     #  (  ps:寫成 done < data.txt  則重定向從data.txt中按行讀取數據)

 res=10
 while [ $res -gt 0 ] 
 do
      echo -n "$res   "
      let "res-=1"
 done
 echo "done"  

Shell編程------循環語句