时间戳问题可以更改系统时间，也可以更改文件的修改时间
sudo date -s ‘20160727 18:51:56’ //sudo date -s 20160727 //sudo date -s 18:51:56
Usage: touch [OPTION]… FILE…
Update the access and modification times of each FILE to the current time.
Mandatory arguments to long options are mandatory for short options too.
-a change only the access time
-c, –no-create do not create any files
-d, –date=STRING parse STRING and use it instead of current time
-f (ignored)
-m change only the modification time //sudo touch -m filename //sudo touch -m ./*
-r, –reference=FILE use this file ‘s times instead of current time
-t STAMP use [[CC]YY]MMDDhhmm[.ss] instead of current time
–time=WORD change the specified time:
WORD is access, atime, or use: equivalent to -a
WORD is modify or mtime: equivalent to -m
–help display this help and exit
–version output version information and exit
Note that the -d and -t options accept different time-date formats.
If a FILE is -, touch standard output.
参考文献：
https://blog.csdn.net/junjun5156/article/details/52042612