系统每隔一段时间自动pull代码

#!/bin/bash
while true;do
    dd=$( date -u )
    echo $dd,"start pull wmsinventoryapiwms6.2"
    cd /e/project/wmsinventoryapiwms6.2
    git pull
 
 
    echo $dd,"start pull wmsadminwms6.2"
    cd /e/project/wmsadminwms6.2
    git pull
 
    echo $dd,"start pull wmsadminapiwms6.2"
    cd /e/project/wmsadminapiwms6.2
    git pull
 
    sleep 1800
 
done