shell exec命令执行shell打印输出到一个文件

[root@master ~]# cat 1.sh 
#!/bin/bash

exec 1>> /tmp/2.log 2>>/tmp/2.log
date 
echo 111
ldkkdfkslfds
date
[root@master ~]# ./1.sh 
[root@master ~]# cat /tmp/2.log 
Sat Jun  9 15:08:19 UTC 2018
111
./1.sh: line 6: ldkkdfkslfds: command not found
Sat Jun  9 15:08:19 UTC 2018
Sat Jun  9 15:10:39 UTC 2018
111
./1.sh: line 6: ldkkdfkslfds: command not found
Sat Jun  9 15:10:39 UTC 2018