ServerBuddies Support Blog

There are several general features of all LVM CLI commands.

When sizes are required in a command line argument, units can always be specified explicitly. If you do not specify a unit, then a default is assumed, usually KB or MB. LVM CLI commands do not accept fractions.

Where commands take volume group or logical volume names as arguments, the full path name is optional. A logical volume called lvol0 in a volume group called vg0 can be specified as vg0/lvol0. Where a list of volume groups is required but is left empty, a list of all volume groups will be substituted. Where a list of logical volumes is required but a volume group is given, a list of all the logical volumes in that volume group will be substituted. For example, the lvdisplay vg0 command will display all the logical volumes in volume group vg0.

All LVM commands accept a -v argument, which can be entered multiple times to increase the output verbosity. For example, the following examples shows the default output of the lvcreate command.

The following command shows the output of the lvcreate command with the -v argument.

All LVM objects are referenced internally by a UUID, which is assigned when you create the object.

dig, or domain information groper, provides the ability to query any domain server for information about the domains it serves. It operates in both an interactive mode and a batch query mode.

Using dig is much like using host, in that in its simplest mode you enter just the command and the name to lookup.

However, dig is more verbose by default and presents a much wider array or information, though in a somewhat less readable form.

Just like host, it is possible to query your default system resolver, or you can query a name server specified on the command line. For example, I could query name server about the google.com domain.

Above, we have a large amount of information, though not all of it is generally useful to us. First is the version of dig, and the command line options we specified.

The comes some status information, including the NOERROR designator that indicates the name was retrieve without error. If the domain did not exist, or could not be queried, there would be an NXDOMAIN error or some other error. Next are the flags of the query.

In this case, we have one query and one answer which are contained in the QUESTION and ANSWER sections below it. The next two items inform us of the number of AUTHORITY and ADDITIONAL sections that follow. In this case, the authority section gives us the primary and secondary name servers for this domain, ns1.serverbuddies.com and ns2.serverbuddies.com, and the additional section provides the IP addresses of those name servers.

The last few lines give the time the query required, the server that was queried and the port on which it was queried, the time and date on which the query was made, and the size of the message received from the name server.

Like host, dig has a mode in which you can query all of the information available about the domain. This can be done by appending the ANY argument to the end of the command line. Furthermore, the options NS, MX, CNAME, etc. are also available and do just what you would expect.

Reference - for more please check - http://doxfer.com/Webmin/