touch 命令是 Unix/Linux 操作系统的一个标准程序，它用于创建、改变和修改文件的时间戳。

touch 命令的选项

touch [options] file

-a, change the access time only
-c, if the file does not exist, do not create it
-d, update the access and modification times
-m, change the modification time only
-r, use the access and modification times of file
-t, creates a file using a specified time [[CC]YY]MMDDhhmm[.SS]