linux是一个文件型操作系统，在linux下一切皆文件。
目录、字符设备、块设备、管道、套接字、符号连接文件等在linux下统统都是文件。
linux下的文件类型分为以下几种类型：
1. 正规文件，
2. 目录，
3. 字符设备，
4. 块设备，
5. 套接字文件，
6. 管道，
7. 符号链接文件。
目前我知道有两种方法查看文件类型：
1. 使用ls -l进行查看，
2. 使用stat命令进行查看
sh-# ls -l /tmp/file.txt
-rw-r--r-- 1 root root 0 Oct 12 09:45 /tmp/file.txt
sh-#
sh-# stat /tmp/file.txt
File: "/tmp/file.txt"
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: eh/14d Inode: 42592 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2013-10-12 09:45:41.000000000
Modify: 2013-10-12 09:45:41.000000000
Change: 2013-10-12 09:45:41.000000000
sh-#
sh-# ls -ld /tmp/directory/
drwxr-xr-x 2 root root 40 Oct 12 09:57 /tmp/directory/
sh-#
sh-# stat /tmp/directory/
File: "/tmp/directory/"
Size: 40 Blocks: 0 IO Block: 4096 directory
Device: eh/14d Inode: 57315 Links: 2
Access: (0755/drwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2013-10-12 09:57:09.000000000
Modify: 2013-10-12 09:57:02.000000000
Change: 2013-10-12 09:57:02.000000000
sh-#
sh-# ls -l /dev/console
crw-r--r-- 1 root root 5, 1 Oct 12 09:58 /dev/console
sh-#
sh-# stat /dev/console
File: "/dev/console"
Size: 0 Blocks: 0 IO Block: 4096 character special file
Device: fe00h/65024d Inode: 425 Links: 1 Device type: 5,1
Access: (0644/crw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2013-10-12 09:58:28.000000000
Modify: 2013-10-12 09:58:28.000000000
Change: 2013-10-12 03:48:49.000000000
sh-#
sh-# ls -l /dev/sda1
brw-r--r-- 1 root root 8, 1 Oct 12 03:48 /dev/sda1
sh-#
sh-# stat /dev/sda1
File: "/dev/sda1"
Size: 0 Blocks: 0 IO Block: 4096 block special file
Device: fe00h/65024d Inode: 722 Links: 1 Device type: 8,1
Access: (0644/brw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2013-10-12 03:48:49.000000000
Modify: 2013-10-12 03:48:49.000000000
Change: 2013-10-12 03:48:49.000000000
sh-#
sh-# ls -l /bin/cp
lrwxrwxrwx 1 root root 15 Oct 12 03:47 /bin/cp -> /openbox/bin/cp
sh-# stat /bin/cp
File: "/bin/cp -> /openbox/bin/cp"
Size: 15 Blocks: 0 IO Block: 4096 symbolic link
Device: fe00h/65024d Inode: 360 Links: 1
Access: (0777/lrwxrwxrwx) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2013-10-12 03:47:22.000000000
Modify: 2013-10-12 03:47:22.000000000
Change: 2013-10-12 03:47:22.000000000
sh-#
sh-# mkfifo /tmp/fifo
sh-# ls -l /tmp/fifo
prw-r--r-- 1 root root 0 Oct 12 10:05 /tmp/fifo
sh-#
sh-# stat /tmp/fifo
File: "/tmp/fifo"
Size: 0 Blocks: 0 IO Block: 4096 fifo
Device: eh/14d Inode: 68387 Links: 1
Access: (0644/prw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2013-10-12 10:05:33.000000000
Modify: 2013-10-12 10:05:33.000000000
Change: 2013-10-12 10:05:33.000000000
sh-#