命令说明：
touch #创建文件或更改文件的时间戳
常用参数：
-a #修改文件的访问时间(access),同时文件的改变时间(change)也会更新
-m #修改文件的修改时间(modify),同时文件的改变时间(change)也会更新
范例实践：
#在/tmp目录下和/root目录下创建chenliang.txt文件
[root@db01 ~]# touch /tmp/chenliang.txt /root/chenliang.txt
[root@db01 ~]# ll /tmp/chenliang.txt /root/chenliang.txt
-rw-r--r-- 1 root root 0 Nov 29 18:27 /root/chenliang.txt
-rw-r--r-- 1 root root 0 Nov 29 18:27 /tmp/chenliang.txt
#在/chenliang/目录下创建liangliang01~10.txt文件
[root@db01 ~]# mkdir /chenliang
[root@db01 ~]# touch /chenliang/liangliang{01..10}.txt
[root@db01 ~]# ll /chenliang/*
-rw-r--r-- 1 root root 0 Nov 29 18:32 /chenliang/liangliang01.txt
-rw-r--r-- 1 root root 0 Nov 29 18:32 /chenliang/liangliang02.txt
-rw-r--r-- 1 root root 0 Nov 29 18:32 /chenliang/liangliang03.txt
-rw-r--r-- 1 root root 0 Nov 29 18:32 /chenliang/liangliang04.txt
-rw-r--r-- 1 root root 0 Nov 29 18:32 /chenliang/liangliang05.txt
-rw-r--r-- 1 root root 0 Nov 29 18:32 /chenliang/liangliang06.txt
-rw-r--r-- 1 root root 0 Nov 29 18:32 /chenliang/liangliang07.txt
-rw-r--r-- 1 root root 0 Nov 29 18:32 /chenliang/liangliang08.txt
-rw-r--r-- 1 root root 0 Nov 29 18:32 /chenliang/liangliang09.txt
-rw-r--r-- 1 root root 0 Nov 29 18:32 /chenliang/liangliang10.txt
#修改/chenliang/liangliang01.txt文件的访问时间（访问时间的更新，改变时间也会随着更新）
[root@db01 ~]# stat /chenliang/liangliang01.txt
File: `/chenliang/liangliang01.txt'
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: 803h/2051d Inode: 1177349 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2018-11-29 18:32:53.644717804 +0800
Modify: 2018-11-29 18:32:53.644717804 +0800
Change: 2018-11-29 18:32:53.644717804 +0800
[root@db01 ~]# touch -a /chenliang/liangliang01.txt
[root@db01 ~]# stat /chenliang/liangliang01.txt
File: `/chenliang/liangliang01.txt'
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: 803h/2051d Inode: 1177349 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2018-11-29 18:36:35.675763737 +0800
Modify: 2018-11-29 18:32:53.644717804 +0800
Change: 2018-11-29 18:36:35.675763737 +0800
#修改/chenliang/liangliang02.txt文件的修改时间（修改时间的更新，改变时间也会随着更新）
[root@db01 ~]# stat /chenliang/liangliang02.txt
File: `/chenliang/liangliang02.txt'
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: 803h/2051d Inode: 1177350 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2018-11-29 18:32:53.644717804 +0800
Modify: 2018-11-29 18:32:53.644717804 +0800
Change: 2018-11-29 18:32:53.644717804 +0800
[root@db01 ~]# touch -m /chenliang/liangliang02.txt
[root@db01 ~]# stat /chenliang/liangliang02.txt
File: `/chenliang/liangliang02.txt'
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: 803h/2051d Inode: 1177350 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2018-11-29 18:32:53.644717804 +0800
Modify: 2018-11-29 18:40:22.144336030 +0800
Change: 2018-11-29 18:40:22.144336030 +0800