touch命令的作用（linux中touch命令的功能与格式）

如果创建一个新文件有很多种方法，比如:

vi file
cat > file
echo "hello,world" > file
touch file
touch命令不仅可以创建新文件，而且可以修改文件的时间属性;

格式: touch [option] [file]

备注:

1) -t选项的时间格式[[CC]YY]MMDDhhmm[.ss]说明:

2) touch命令的几点说明:

１，同时创建一个或者多个空文件

linuxidc@linuxidc:~/linux/mkdir$ ls
linuxidc@linuxidc:~/linux/mkdir$ touch a.txt
linuxidc@linuxidc:~/linux/mkdir$ ls
a.txt
linuxidc@linuxidc:~/linux/mkdir$ touch b.txt c.txt
linuxidc@linuxidc:~/linux/mkdir$ ls
a.txt b.txt c.txt
linuxidc@linuxidc:~/linux/mkdir$ touch {1..5}.txt
linuxidc@linuxidc:~/linux/mkdir$ ls
1.txt 2.txt 3.txt 4.txt 5.txt a.txt b.txt c.txt

2，创建文件，并用stat查看文件的属性状态信息

linuxidc@linuxidc:~/linux/mkdir$ touch linuxidc.txt
linuxidc@linuxidc:~/linux/mkdir$ stat linuxidc.txt 
 File: 'linuxidc.txt'
 Size: 0 Blocks: 0 IO Block: 4096 regular empty file
linuxidcice: 807h/2055d Inode: 9569451 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ linuxidc) Gid: ( 1000/ linuxidc)
Access: 2018-05-01 17:25:16.439856937  0800
Modify: 2018-05-01 17:25:16.439856937  0800
Change: 2018-05-01 17:25:16.439856937  0800
 Birth: -
最后有３个时间
Access time: 最后访问时间，查看文件的内容时，这个时间会改变，使用cat命令查看文件时，可以看出Access time已经变了
linuxidc@linuxidc:~/linux/mkdir$ stat linuxidc.txt 
 File: 'linuxidc.txt'
 Size: 0 Blocks: 0 IO Block: 4096 regular empty file
linuxidcice: 807h/2055d Inode: 9569451 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ linuxidc) Gid: ( 1000/ linuxidc)
Access: 2018-05-01 17:25:16.439856937  0800
Modify: 2018-05-01 17:25:16.439856937  0800
Change: 2018-05-01 17:25:16.439856937  0800
 Birth: -
linuxidc@linuxidc:~/linux/mkdir$ cat linuxidc.txt 
linuxidc@linuxidc:~/linux/mkdir$ stat linuxidc.txt 
 File: 'linuxidc.txt'
 Size: 0 Blocks: 0 IO Block: 4096 regular empty file
linuxidcice: 807h/2055d Inode: 9569451 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ linuxidc) Gid: ( 1000/ linuxidc)
Access: 2018-05-01 17:27:51.887215139  0800
Modify: 2018-05-01 17:25:16.439856937  0800
Change: 2018-05-01 17:25:16.439856937  0800
 Birth: -
Modify time:最后修改时间，修改文件内容，文件的修改时间会改变。访问时间和状态改变时间 也发生变化
linuxidc@linuxidc:~/linux/mkdir$ stat linuxidc.txt 
 File: 'linuxidc.txt'
 Size: 0 Blocks: 0 IO Block: 4096 regular empty file
linuxidcice: 807h/2055d Inode: 9569451 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ linuxidc) Gid: ( 1000/ linuxidc)
Access: 2018-05-01 17:27:51.887215139  0800
Modify: 2018-05-01 17:25:16.439856937  0800
Change: 2018-05-01 17:25:16.439856937  0800
 Birth: -
linuxidc@linuxidc:~/linux/mkdir$ vim linuxidc.txt 
linuxidc@linuxidc:~/linux/mkdir$ stat linuxidc.txt 
 File: 'linuxidc.txt'
 Size: 5 Blocks: 8 IO Block: 4096 regular file
linuxidcice: 807h/2055d Inode: 9569550 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ linuxidc) Gid: ( 1000/ linuxidc)
Access: 2018-05-01 17:29:34.982228802  0800
Modify: 2018-05-01 17:29:34.982228802  0800
Change: 2018-05-01 17:29:35.018231392  0800
 Birth: -
Change time:状态改变时间,修改文件内容，移动文件，或者改变文件属性等，文件的change time会发生改变.
１，移动文件( 重命名 ), change time 发生改变:
linuxidc@linuxidc:~/linux/mkdir$ stat linuxidc.txt 
 File: 'linuxidc.txt'
 Size: 5 Blocks: 8 IO Block: 4096 regular file
linuxidcice: 807h/2055d Inode: 9569550 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ linuxidc) Gid: ( 1000/ linuxidc)
Access: 2018-05-01 17:29:34.982228802  0800
Modify: 2018-05-01 17:29:34.982228802  0800
Change: 2018-05-01 17:29:35.018231392  0800
 Birth: -
linuxidc@linuxidc:~/linux/mkdir$ mv linuxidc.txt linuxidc2.txt
linuxidc@linuxidc:~/linux/mkdir$ stat linuxidc2.txt 
 File: 'linuxidc2.txt'
 Size: 5 Blocks: 8 IO Block: 4096 regular file
linuxidcice: 807h/2055d Inode: 9569550 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ linuxidc) Gid: ( 1000/ linuxidc)
Access: 2018-05-01 17:29:34.982228802  0800
Modify: 2018-05-01 17:29:34.982228802  0800
Change: 2018-05-01 17:32:25.392863791  0800

2，修改文件的权限，change time发生了改变

linuxidc@linuxidc:~/linux/mkdir$ stat linuxidc2.txt 
 File: 'linuxidc2.txt'
 Size: 5 Blocks: 8 IO Block: 4096 regular file
linuxidcice: 807h/2055d Inode: 9569550 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ linuxidc) Gid: ( 1000/ linuxidc)
Access: 2018-05-01 17:29:34.982228802  0800
Modify: 2018-05-01 17:29:34.982228802  0800
Change: 2018-05-01 17:32:25.392863791  0800
 Birth: -
linuxidc@linuxidc:~/linux/mkdir$ chmod 777 linuxidc2.txt 
linuxidc@linuxidc:~/linux/mkdir$ stat linuxidc2.txt 
 File: 'linuxidc2.txt'
 Size: 5 Blocks: 8 IO Block: 4096 regular file
linuxidcice: 807h/2055d Inode: 9569550 Links: 1
Access: (0777/-rwxrwxrwx) Uid: ( 1000/ linuxidc) Gid: ( 1000/ linuxidc)
Access: 2018-05-01 17:29:34.982228802  0800
Modify: 2018-05-01 17:29:34.982228802  0800
Change: 2018-05-01 17:33:31.602584110  0800
 Birth: -
touch -m修改文件的modify和change时间
linuxidc@linuxidc:~/linux/mkdir$ stat linuxidc2.txt 
 File: 'linuxidc2.txt'
 Size: 5 Blocks: 8 IO Block: 4096 regular file
linuxidcice: 807h/2055d Inode: 9569550 Links: 1
Access: (0777/-rwxrwxrwx) Uid: ( 1000/ linuxidc) Gid: ( 1000/ linuxidc)
Access: 2018-05-01 17:29:34.982228802  0800
Modify: 2018-05-01 17:29:34.982228802  0800
Change: 2018-05-01 17:33:31.602584110  0800
 Birth: -
linuxidc@linuxidc:~/linux/mkdir$ touch -m linuxidc2.txt 
linuxidc@linuxidc:~/linux/mkdir$ stat linuxidc2.txt 
 File: 'linuxidc2.txt'
 Size: 5 Blocks: 8 IO Block: 4096 regular file
linuxidcice: 807h/2055d Inode: 9569550 Links: 1
Access: (0777/-rwxrwxrwx) Uid: ( 1000/ linuxidc) Gid: ( 1000/ linuxidc)
Access: 2018-05-01 17:29:34.982228802  0800
Modify: 2018-05-01 17:34:31.678864985  0800
Change: 2018-05-01 17:34:31.678864985  0800
touch -d修改创建后的文件的修改时间
linuxidc@linuxidc:~/linux/mkdir$ ls -lh linuxidc2.txt 
-rwxrwxrwx 1 linuxidc linuxidc 5 5月 1 17:34 linuxidc2.txt
linuxidc@linuxidc:~/linux/mkdir$ touch -d 20190218 linuxidc2.txt 
linuxidc@linuxidc:~/linux/mkdir$ ls -lh linuxidc2.txt 
-rwxrwxrwx 1 linuxidc linuxidc 5 2月 18 2019 linuxidc2.txt
linuxidc@linuxidc:~/linux/mkdir$ stat linuxidc2.txt 
 File: 'linuxidc2.txt'
 Size: 5 Blocks: 8 IO Block: 4096 regular file
linuxidcice: 807h/2055d Inode: 9569550 Links: 1
Access: (0777/-rwxrwxrwx) Uid: ( 1000/ linuxidc) Gid: ( 1000/ linuxidc)
Access: 2019-02-18 00:00:00.000000000  0800
Modify: 2019-02-18 00:00:00.000000000  0800
Change: 2018-05-01 17:37:13.031347481  0800
 Birth: -