File status

_$: stat u_ex130502.zip 
  File: `u_ex130502.zip'
  Size: 1712      	Blocks: 8          IO Block: 4096   regular file
Device: fc02h/64514d	Inode: 1044509     Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1008/txbackup)   Gid: ( 1011/txbackup)
Access: 2013-06-13 11:17:09.002075752 +0200
Modify: 2013-06-04 16:41:01.000000000 +0200
Change: 2013-06-13 10:29:29.793853148 +0200
 Birth: -

Create a file of a certain size

5000 bytes, all zeroes (zippable):

_$: dd if=/dev/zero of=upload_test bs=5000 count=1

10M, all zeroes (zippable):

_$: dd if=/dev/zero of=upload_test bs=1M count=10

10M, random (unzippable):

_$: dd if=/dev/urandom of=blob bs=1M count=10

Change the access and modification date

_$: touch myfile --date="2014/06/04 12:00:00"
_$: touch -t 201406041200 myfile

Copy files between two filesystems

_$: dd if=devops3.tar of=/var/lib/libvirt/images/virtualbox/devops3.tar bs=100M

Find the filesystem in which a file is mount

_$: df /path/to/file
Filesystem      1K-blocks    Used Available Use% Mounted on
/path/to/file   162545156 4126812 151607132   3% /another/path/to/file