linux下的stat du df and devices

df
   display overall disk utlilization information for mounted filesystems on directories.usually,directories are device file for partition.such as /dev/hda1.but using another file or directories are yields information on the partition that holds the file or directory.if directories are omitted,information for mounted filesystems on all devices in /etc/fstab are displayed
df -h display results in a human-readable format.
 df -i display information on remaining inodes rather than the default disk space information
 df -m
 df . quitely determine which partition the current working directory
 
stat
  display file or filesystem status. include the midify time, size,block counts, inode counts and so on.
  example: stat /usr
  
du
  display disk utilization information for directories .
   -a show all files,not just directories
   -c produce a grand total for all listed items
   -h display results in a human-readable format, include suffixes such as M(megabytes) and G(gigabytes)
   -s prints a summary for each of the directories specified,instead of totals for each subdirectory found recursively
   example:
   du /etc/rc.d
   du -s /etc
   
devices linux filesystems and the filesystem hierarchy standard
 IDE hard disk
 /dev/hda the primary master disk
 /dev/hdb primary slave disk
 /dev/hdc secondary master disk
 /dev/hdd secondary slave
 SCSI hard disk (have 15 devices on a single bus)
 /dev/sda
 /dev/sdb
 ...........
 a typical pc with a single hard disk on the primary IDE interface and a single CD_ROM on the second interface would have disk drive /dev/hda and CD_ROM /dev/hdc
 on each disk in a pc, there may be between 1 and 16 partitions.1 to 12 logical partitions may be created. logical partition are numbered from 5 to 16. under this pc partitioning scheme. a maximum of 15 partitions with filesystems may exist on a single physical(3 primary plus 12 logical)