pvdisplay – shows you the current state of your physical volumes.
vgdisplay – shows you all volume groups
lvdisplay – shows you all logical volumes
lvscan – shows you all active volumes (disks)
lvs – is like lvscan but shows you less detail.
pvscan – scans all disks for physical volumes and shows disk space.
How to check CentOS version, use command as below
For the CentOS on 32 or 64 bit, can use command as below
For upgrade the CentOS to the latest version
rsync is a program that behaves in much the same way that rcp does, but has many more options and uses the rsync remote-update protocol to greatly speed up file transfers when the destination file already exists.
The rsync remote-update protocol allows rsync to transfer just the differences between two sets of files across the network link, using an efficient checksum-search algorithm described in the technical report that accompanies this package.
Debian or Ubuntu Linux
apt-get install rsync
sudo apt-get install rsync
Red Hat Enterprise Linux (RHEL)
CentOS/Fedora Core Linux
yum install rsync
Command to drop cache
To free pagecache:
echo 1 > /proc/sys/vm/drop_caches
To free dentries and inodes:
echo 2 > /proc/sys/vm/drop_caches
To free pagecache, dentries and inodes:
echo 3 > /proc/sys/vm/drop_caches
Strongly advise to run sync first before do that. You can use command as below
sync;echo 3 > /proc/sys/vm/drop_caches
When modifying a particular account under Modify Account in cPanel, the error “Unable to fetch the cPanel user file for username” occurs
(1) First, you need to make sure the cPanel user file is there
ls -lah username
(2) Make sure the permission is correct
-rw-r—– 1 root username 000 Jan 0 00:00 username
(3) Then run the cPanel command
If it still can not solve! Use the hard way, manual way. Open the cPanel user file and edit it manually(either owner or etc), and go back to WHM and modify the account again. If should be done now. 🙂