my system is RHEL5.2
[root@joy ~]# uname -r
2.6.18-92.el5
[root@joy ~]# mount
/dev/sda3 on / type ext3 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
/dev/sda1 on /boot type ext3 (rw)
tmpfs on /dev/shm type tmpfs (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
/dev/sdb on /mnt type ext3 (rw)
[root@joy ~]# df -T
Filesystem Type 1K-blocks Used Available Use% Mounted on
/dev/sda3 ext3 7002712 2631988 4009264 40% /
/dev/sda1 ext3 101086 11139 84728 12% /boot
tmpfs tmpfs 257744 0 257744 0% /dev/shm
/dev/sdb ext3 20642428 176200 19417652 1% /mnt

create a empty file,but this file size is 4k
[root@joy tmp]# touch joy
[root@joy tmp]# ll -sh joy
4.0K -rw-r--r-- 1 root root 0 Oct 30 17:23 joy
[root@joy tmp]# stat joy
File: `joy'
Size: 0 Blocks: 8 IO Block: 4096 regular empty file
Device: 803h/2051d Inode: 1421279 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2009-10-30 17:23:50.000000000 +0800
Modify: 2009-10-30 17:23:50.000000000 +0800
Change: 2009-10-30 17:23:50.000000000 +0800
append 2 byte data for the file ,size change 8k
[root@joy tmp]# echo i > joy
[root@joy tmp]# ll -sh joy
8.0K -rw-r--r-- 1 root root 2 Oct 31 04:59 joy

There is a difference between the actual size of the content of a file (in your case, 2 bytes) and the size it takes up on disk.
The latter is always a multiple of the block size, which in your case seems to be 8KB (a fairly standard value).
This is related to how disk reading/writing/caching works, which is related to your operating system (Linux) and the
organization of the data on your hard drive (the filesystem).

Hi,

This is probably blocksize related.

The blocksize is the minimum size that can be occupied on a disk.

A file that is one bit, will occupy 1 block, which size could be anything from 1K to 64K (largest I've seen).

I don't know which alias ll has, but maybe the -s option is in there.

Blocksize is in red, filesize is in green.

thank you

what is this?
Device: 803h/2051d
.000000000 +0800

Hi,

This +0800 is the offset compared to UTC (+ 8 hours would put you in this area of the world).

This 803h/2051d shows (hex and decimal) the physical device and partition that the file is on.

Try a ls -l /dev/sd[ab]* you should see something like this:
The bold entry is 0803 (major number 8, minor number 3)

Hope this helps

thank you,but my compute has only a harddisk. why start disk 8

Your computer may have only one hard disk device, but probably has multiple bus connections to add more.

Hi,

This is by convention.

There are a lot of different devices you can connect to your box, a (scsi) HD is just one of those.

Take a look at this article: LINUX ALLOCATED DEVICES

If you scroll down to 8 block you see the scsi disk devices (8 being the so called major number), next to it a breakdown per disk (sda/sdb etc) with the starting minor number.

One none partitioned scsci disk will have major number 8 and minor number 0. The first partition will be 8 1, then 8 2 etc. This also explains why you can have a maximum of 15 partitions on one disk. (0 -> 16. One for the disk itself, 15 for partitions).

Hope this clears things up a bit.

Thank you very much.

Also note that the directory file-sizes may be out of date at any particular time, because the directory entries are updated infrequently.