linux file size check

file system specification
:$mount

/dev/sda2 on / type ext4 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw,rootcontext="system_u:object_r:tmpfs_t:s0")
/dev/sda1 on /boot type ext4 (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
/tmp on /tmp type none (rw,bind)
/var/tmp on /var/tmp type none (rw,bind)
/home on /home type none (rw,bind)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
/dev/sda4 on /oradata0 type ext4 (rw)

file size check current file system  with GigaByte
df -h ./

Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2              50G   30G   17G  64% /

file size check current directory with GigaByte

du -sh directory : sum current directory

945M   directory

du -h directory :  child directory size list 

16K     directory/child directory/.../ 

16K     directory/child directory/../ 

1.3M   directory/child directory/ 

5.9M   directory/child directory/ 

7.5M   directory/child directory/ 

16K     directory/child directory/ 

7.7M   directory/child directory/ 

16K     directory/child directory/

blocksize specification :
 $dumpe2fs /dev/sda2 |grep "Block size"
       
dumpe2fs 1.41.12 (17-May-2010)
Block size:               4096