Shell 控制并发

#!/bin/bash
c=0
for i in `seq -w 18 31`;do
  while [ $c -ge 3 ];do
    c=$(jobs -p |wc -w)
    sleep 1s
  done
  bash run_cal_us_tmp.sh 201407$i &
  #echo "`sleep 5s`haha" &
  c=$(jobs -p |wc -w)
done

#/bin/bash -x                                             
SPEED=50                                                                                                
mkfifo tmpfifo                                               
exec 6<>tmpfifo                                                                                     

for(( i=0;i<5;i++ ));
do                                                                                                             
    echo $i;                                                                                                   
done >&6

while read tmp<&6
do 
 echo "haha"
done

wait                                                                                                     
exec >&6-