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A way how to execute commands on other tty/pts. A simple echo won’t work because echo writes to the output buffer, while I need to push these commands to the input buffer of the tty/pts.

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <string.h>
#include <unistd.h>

void print_help(char *prog_name) {
        printf("Usage: %s [-n] DEVNAME COMMAND\n", prog_name);
        printf("Usage: '-n' is an optional argument if you want to push a new line at the end of the text\n");
        printf("Usage: Will require 'sudo' to run if the executable is not setuid root\n");

int main (int argc, char *argv[]) {
    char *cmd, *nl = "\n";
    int i, fd;
    int devno, commandno, newline;
    int mem_len;
    devno = 1; commandno = 2; newline = 0;
    if (argc < 3) {
    if (argc > 3 && argv[1][0] == '-' && argv[1][1] == 'n') {
        devno = 2; commandno = 3; newline=1;
    } else if (argc > 3 && argv[1][0] == '-' && argv[1][1] != 'n') {
        printf("Invalid Option\n");
    fd = open(argv[devno],O_RDWR);
    if(fd == -1) {
        perror("open DEVICE");
    mem_len = 0;
    for ( i = commandno; i < argc; i++ ) {
        mem_len += strlen(argv[i]) + 2;
        if ( i > commandno ) {
            cmd = (char *)realloc((void *)cmd, mem_len);
        } else { //i == commandno
            cmd = (char *)malloc(mem_len);

        strcat(cmd, argv[i]);
        strcat(cmd, " ");
  if (newline == 0)
    for (i = 0; cmd[i]; i++)
        ioctl (fd, TIOCSTI, cmd+i);
    if (newline == 1)
        ioctl (fd, TIOCSTI, nl);
    free((void *)cmd);
    exit (0);

Copy the above code to some C file (For eg. tty-send-command.c). Run the following command in the directory you have created the C file in to compile the code.

make tty-send-command

Copy this file to the bin directory.

Start another terminal or switch to any other open terminal that you wish to control and execute the command tty. You can see a sample output below.

@~$ tty

Now to execute a command on /dev/pts/4, run the following command in the controlling/original terminal.

sudo tty-send-command -n /dev/pts/4 echo "Hello there"

You will see that the ls command is executed in /dev/pts/4. The -n option makes tty-send-command send a newline after the command, so that the command gets executed and not just inserted. This utility can infact be used to send any data to other terminals For eg, you could open vim in /dev/pts/4 and then run the following command in the controlling terminal to cause vim to exit in /dev/pts/4.

sudo tty-send-command -n /dev/pts/4 :q

To avoid using sudo all the time, so that the command is easily scriptable, change the owners/permissions of this executable using the following commands.

sudo chown root:root tty-send-command
sudo chmod u+s tty-send-command

What we did was change the owner/group to root and set the setuid bit for the executable which will allow you to run the utility with root permissions.

Setting the setuid bit can become a security risk.

If you are running a mission critical server, or maintaining a storage server loaded with sensitive data, you probably want to closely monitor file access activities within the server. For example, you want to track any unauthorized change in system configuration files such as /etc/passwd.

To monitor who changed or accessed files or directories on Linux, you can use the Linux Audit System which provides system call auditing and monitoring. In the Linux Audit System, a daemon called auditd is responsible for monitoring individual system calls, and logging them for inspection.

In this tutorial, I will describe how to monitor file access on Linux by using auditd.

To install auditd on Debian, Ubuntu:

$ sudo apt-get install auditd

Once installed by apt-get, auditd will be set to start automatically upon boot.

To install auditd on Fedora, CentOS or RHEL:

$ sudo yum install audit

If you want to start auditd automatically upon boot on Fedora, CentOS or RHEL, you need to run the following.

$ sudo chkconfig auditd on

Once you installed auditd, you can configure it by two methods. One is to use a command-line utility called auditctl. The other method is to edit the audit configuration file located at /etc/audit/audit.rules. In this tutorial, I will use the audit configuration file.

The following is an example auditd configuration file.

$ sudo vi /etc/audit/audit.rules
# First rule - delete all

# increase the buffers to survive stress events. make this bigger for busy systems.
-b 1024

# monitor unlink() and rmdir() system calls.
-a exit,always -S unlink -S rmdir

# monitor open() system call by Linux UID 1001.
-a exit,always -S open -F loginuid=1001

# monitor write-access and change in file properties (read/write/execute) of the following files.
-w /etc/group -p wa
-w /etc/passwd -p wa
-w /etc/shadow -p wa
-w /etc/sudoers -p wa

# monitor read-access of the following directory.
-w /etc/secret_directory -p r

# lock the audit configuration to prevent any modification of this file.
-e 2

Once you finish editing the audit configuration, restart auditd.

$ sudo service auditd restart

Once auditd starts running, it will start generating an audit daemon log in /var/log/audit/audit.log as auditing is in progress.

A command-line tool called ausearch allows you to query audit daemon logs for specific violations.

To check if a specific file (e.g., /etc/passwd) has been accessed by anyone, run the following. As shown in the above example audit configuration, auditd checks if /etc/passwd is modified or tampered with using chmod.

$ sudo ausearch -f /etc/passwd
time->Sun May 12 19:22:31 2013
type=PATH msg=audit(1368411751.734:94): item=0 name="/etc/passwd" inode=655761 dev=08:01 mode=0100644 ouid=0 ogid=0 rdev=00:00
type=CWD msg=audit(1368411751.734:94):  cwd="/home/xmodulo"
type=SYSCALL msg=audit(1368411751.734:94): arch=40000003 syscall=306 success=yes exit=0 a0=ffffff9c a1=8624900 a2=1a6 a3=8000 items=1 ppid=14971 pid=14972 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts2 ses=19 comm="chmod" exe="/bin/chmod" key=(null)

The ausearch output above shows that chmod has been applied to /etc/passwd by the root once.

To check if a specific directory (e.g., /etc/secret_directory) has been accessed by anyone, run the following.

$ sudo ausearch -f /etc/secret_directory
time->Sun May 12 19:59:58 2013
type=PATH msg=audit(1368413998.927:108): item=0 name="/etc/secret_directory/" inode=686341 dev=08:01 mode=040755 ouid=0 ogid=0 rdev=00:00
type=CWD msg=audit(1368413998.927:108):  cwd="/home/xmodulo"
type=SYSCALL msg=audit(1368413998.927:108): arch=40000003 syscall=230 success=no exit=-61 a0=bfcdc4e4 a1=b76f0fa9 a2=8c65c70 a3=ff items=1 ppid=2792 pid=11300 auid=1001 uid=1001 gid=1001 euid=1001 suid=1001 fsuid=1001 egid=1001 sgid=1001 fsgid=1001 tty=pts1 ses=2 comm="ls" exe="/bin/ls" key=(null)

The output shows that /etc/secret_directory was looked into by Linux UID 1001.

In our example audit configuration, auditd was placed in immutable mode, which means that if you attempt to modify /etc/audit/audit.rules, and restart auditd, you will get the following error.

$ sudo /etc/init.d/auditd restart
Error deleting rule (Operation not permitted)
The audit system is in immutable mode, no rules loaded

If you want to be able to modify the audit rules again after auditd is put in immutable mode, you need to reboot your machine after changing the rules in /etc/audit/audit.rules.

If you want to enable daily log rotation for the audit log generated in /var/log/audit directory, use the following command in a daily cronjob.

$ sudo service auditd rotate

Veritas Cheat Sheet


vxdisk list
 List all disks used by Veritas (VX).

vxdisk list <diskname>
 Display detailed information about a 
 single disk, including mutlipathing
 information, size, type, Vx version,
 and more.

 Display report style information about
 the current status of all Vx componants,
 including disks, subdisks, plexes, and

vxprint <componant>
 Display report style information about
 the current status of ONLY the componant
 you request. So for instance, 
 "vxprint vol01" shows information about
 all subcomponants of vol01. This works
 for plexes, disk groups, etc.

vxprint -hrt
 Display detailed information about all
 Vx componanats, including stwdith, 
 ncolumns, offsets, layout type, read-
 policy, and more. This is best for
 a true picture of your configuration.

vxdg list
 Display listing and state information
 of all Disk Groups.

vxdg list <diskgroup name>
 Display detailed information about
 a diskgroup, including flags, version,
 logs status, etc.

 Display volume status and volume type.
 By default, only displays "rootdg", 
 to display a diffrent Disk Group,
 use "vxinfo -g <dgname>".

vxassist maxgrow <volume>
 This command will output the maximum size
 the volume specified can increased by,
 specified in sectors.


vxdiskadd <devname>
 Adds a disk to Vx by Initializing and Encapsolating
 it. Specified by its device name (ex: c0t1d0s2).
 NOTE: You'll need to reboot to finalize the
 disk addition!
 This command, can also be used to add a disk to
 a specified disk group. Just follow the prompts.
 No reboots needed for changing DG's.

vxedit rename <oldname> <newname>
 Rename a Vx disk. Ex: "vxedit rename disk01 disk05"

vxedit set reserve=on <diskname>
 Sets the "reserve" flag to a Vx disk. This
 is used to keep specific disks from being
 accidentally, or generally used.

vxdisk offline <diskname>
 Used to "offline" a disk. The disk should
 be removed from its diskgroup before being 

vxdisk rm <devname>
 Used to remove disks from Vx control completely.
 Ex: "vxdisk rm c0t1d0s2" Make sure to 
 removed the disk from its diskgroup, and offline
 the disk before removing it.

vxedit set spare=on <diskname>
 Sets the "spare" flag to a Vx disk. This is used
 to make the specified disk a hot spare, which
 is then added to the "hot spare pool".

vxedit set spare=off <diskname>
 Same as above but removes the disk from the
 "hot spare pool".


vxdg init <diskgroup> <diskname>=<devname>
 Creates a new disk group, and assigns the naming
 scheme to the first disk added to the group.
 ex: "vxdg init newdg newdg01=c0t10d0s2".
 NOTE: This is kinda tricky because the disk that
 you're adding can't be a member of ANY DG, but
 must be initialized. It's easier to use
 "vxdiskadd", and add the disk to a newdg by
 specifying a new DG name for the DG field.

vxdg deport <diskgroup>
 Disabled a diskgroup, but doesn't remove it. Often
 used as an organized pool of disk to realocate, and
 to moved DG's from one system to another.

vxdg import <diskgroup>
 Reverse of above. Enables local access to the specified
 disk group.

vxdg -n <newdgname> <olddgname>
 Change a Disk Groups name.

vxdg list <dgname>
 Use this to check the version numbers of Disk
 Groups. Shows other details about the DG too.

vxdg destroy <dgname>
 Removes the specified DG, and frees all its disks
 back to general use by Vx.

-= Quick Chart!: Disk Group Version Number Translation

 VxVM Introduced Supported
 Release Version Versions
 ------- ------------ ---------
 1.2 10 10
 1.3 15 15
 2.0 20 20
 2.2 30 30
 2.3 40 40
 2.5 50 50
 3.0 60 20-60


vxmake sd <subdiskname> <disk>,<offset>,<length>
 Creates a subdisk with the specified name,
 and by the offset and length specified.
 ex: "vxmake sd disk02-01 disk02,0,8000"
 NOTE: If you are going to add this subdisk
 to a plex, its good to check the other
 subdisks in that plex to see what their
 lengths and offsets are, use the command:
 "vxprint -st"

vxedit rm <subdiskname> 
 Removes a subdisk. 
vxsd assoc <plexname> <subdiskname>,....
 Associates the specified subdisks to
 the specified plex. Example:
 "vxsd assoc vol01-03 disk01-01,disk02-01" 
 NOTE: Striped volumes are diffrent, 
 you need to specify the column# so 
 use the following: 
vxsd -l <col#/offset> assoc <plexname> <subdiskname>,... 
 Same as above, but used for associating
 subdisks to a striped plex. Use the command 
 "vxprint -st" to see what other subdisk
 in the plex look like, and then set the
 new subdisks column number and offset
 (found in the seventh column of output)
 to the appropriate value.
vxsd aslog <plex> <subdiskname>
 Adds a log subdisk to the specified plex. 
 Ex: "vxsd aslog vol01-02 disk03-01" 

vxsd dis <subdiskname>
 Disassociates the specified subdisk from its
 current plex. 


vxmake plex <plexname> sd=<subdiskname>,<subdiskname>,.... 
 Creates a new plex by the name specified and
 assigns the specified subdisks to it.

vxmake plex <plexname> layout=<layout> stwidth=<stwidth> ncolumn=<ncolumn> sd=...
 Like above command, but specifies layout type
 as defined by <layout>, which is used for creation
 of striped and RAID5 plexes. The layout is
 constrained by the defined number of columns,
 and stripe width. Subdisks specified are
 added to the created plex. 

vxplex att <volname> <plexname>
 Associates specified plex with specified volume.
 (Adds a mirror) 
 NOTE: Attachment will take a while. Watch
 it with Vxtask, or via vxprint

vxplex dis <plexname>
 Disassociate specified plex from its connected 

vxedit -r rm <plexname>
 Remove the plex.

vxmend off <plexname>
 Offlines a plex for repair to it's disks.

vxplex det <plexname>
 Detaches specified plex from its connected
 volume, but maintians association with it's
 volume. The plex is no longer used
 for I/O untill it is (re)attached.

vxmend fix clean <plexname>
 Used to clean plexes that are in the
 "unclean" state. Used with unstartable

vxplex mv <originalplex> <newplex>
 Moves the data content from the origonal
 plex onto a new plex. 
 NOTE: The old plex must be active (ENABLED).
 The new plex should be the same length, or
 larger than the old plex. The new plex 
 must not be associated with another volume.

vxplex cp <volume> <newplex>
 Copies the data from the specified volume
 to a new plex.
 NOTE: The new plex cannot be associated
 with any other volume. The new plex,
 further, will NOT be attached to 
 the specified volume. (Also, see notes
 from above)


vxassist make <volumename> <length>
 Creates a new volume with the name specified
 and is made to the length specified. 
 Ex: "vxassist make newvol 10m"
 NOTE: This command will pull disk space
 from the generally avalible Vx disk space.

vxassist make <volname> <length> layout=<layouttype> <disk> <disk> ....
 Like the above command, but with layout specified.
 The most common layouts are: striped and raid5
 ex: "vxassist make newvol 100m layout=raid5 disk01 disk02 disk03"
 NOTE: See the vxassist(1M) man page for more information.

vxmake vol <volname> len=<length> plex=<plexname>,...
 Creates a new volume of specified length (usually
 in sectors), and attachs the specified plexes to that
 volume. Useful for creating volumes to house 
 copied or moved plexes.
 NOTE: See the vxmake(1M) man page for more information.

vxvol init <state> <volname> [plexname]
 Manually sets the state of a volume.
 NOTE: Not for the squimish.

vxassist maxsize [layout=raid5]
 Returns the maximum size avalible via Vx to create
 a new volume. By adding "layout=raid5" to the command
 the calulations take into account losse due
 to raid5. Output is in sectors and Megs.

vxassist maxgrow <volname>
 Returns the maximum ammount of Vx space that
 can be added to the specified volume.

vxassist mirror <volname>
 Creates a mirror for the specified volume.
 NOTE: Think of this as "handsfree plex creation".
 This is fast, but the disks you want used 
 may not be used... often best to do manually.

vxassist addlog <volname>
 Adds a Dirty Region Log (DRL) for the specified volume.

vxassist remove log <volname>
 Reverse of above.

vxvol start <volname>
 Starts a volume

vxvol stop <volname>
 Stops a volume. Alternately you can use command as
 such: "vxvol stopall" in order to stop all volumes.

vxassit growto/growby/shrinkto/shrinkby <volname> <length>
 Resizes the volume specified. Use one of the
 following: growto, growby, shrinkto, and shrinkby
 in order to descide what <length> specifies.
 By default length is specified in sectors.
 This does not resize the filesystem inside the volume.
 NOTE: Don't shrink volumes to be less that 
 its contained filesystem! (duh)

vxvol set len=<length> <volname>
 An alternate to above command. Sets the absolute
 lenths of the specified volume to the length
 specified, by default, in sectors. This 
 does not resize the filesystem inside the volume.

 NOTE: There is also a resize(1M) command, used
 for resizing both volume AND filesytem. See
 the man page for that one.

vxedit rm <volname>
 Removes the specified volume. (poof!)
 NOTE: If the volume specified is in the ENABLED
 state, you will need to use the command
 "vxedit -f <volname>". Also, using the "r"
 with "f" will remove all plexes and subdisks
 with the volume. If you didn't guess, "r"
 is Recursive, and "f" is Force.

Misc Stuff:

To calculate the size of a filesystem inside a volume, use
the command:
 fstyp -v <volume-device-path> | head -30 | grep ncg
Ignore the errors. Output will look this this:
 # fstyp -v /dev/vx/rdsk/datadg/vol01 | head -30 | grep ncg
 ncg 17152 size 70254592 blocks 65863396
 # Broken Pipe
 Unknown_fstyp (no matches)
The size found after the label "size" is presented in kilobytes.
You can convert to sectors by multiplying by 2.


To calculate the size of a volume, use vxprint, and look for the
"len". The volume length is in sectors. Convert to kilobytes
by dividing by 2.


Volume Growth Procudure:
1) You can use vxassist to estimate the max size of 
a given volume based on the disks you wish to add:
ex: # vxassist -g rootdg maxgrow vol01 disk01 disk02 disk03

2) Next, actually grow the volume (NOT THE FS) via the 
command (assuming maxgrow outputed 10639360 as the maxsize):
ex:# vxassist -g rootdg growto vol01 10639360 disk01 disk02 disk03

3) Now VxVM grinds away, monitor with vxtask.

4) Now Grow the Filesystem, for UFS use:
# /usr/lib/fs/ufs/mkfs -F ufs -M /export /dev/vx/rdsk/rootdg/vol01 10639360

for VXFS ufs:
# /usr/lib/fs/vxfs/fsadm -b 10639360 -r /dev/vx/rdsk/rootdg/vol01 /mnt

5) Done!


Changing User/Group of a Raw Volume: (ex:)
 vxedit -g xxxdg set group=dba data_vol_123
 vxedit -g xxxdg set user=oracle data_vol_123

This post will cover how to increase the disk space for a VMware virtual machine running Linux that is using logical volume manager (LVM). Firstly we will add a new disk to the virtual machine and then extend the original LVM over this additional space. Basically we will have two physical disks but just one volume group and one logical group that is using the space on both disks together. With this method there is no down time for the virtual machine.

As there are a number of different ways to increase disk space I have also posted some different methods here:

Important Notes: Be very careful when working with the commands in this article as they have the potential to cause a lot of damage to your data. If you are working with virtual machines make sure you take a snapshot of your virtual machine beforehand, or otherwise have some other form of up to date backup before proceeding. It could also be worth cloning the virtual machine first and testing out this method on the clone.

Throughout my examples I will be working with a VMware virtual machine running Debian 6, this was set up with a 20gb disk and we will be adding a new 20gb disk for a total LVM size of 40gb.

Although my examples make use of virtual machines, this method would work with a physical server as well if you have added a new physical disk in and want to use that to expand the LVM.

Identifying the partition type

As this method focuses on working with LVM, we will first confirm that our partition type is actually Linux LVM by running the below command.

fdisk -



As you can see in the above image /dev/sda5 is listed as “Linux LVM” and it has the ID of 8e. The 8e hex code shows that it is a Linux LVM, while 83 shows a Linux native partition. Now that we have confirmed we are working with an LVM we can continue.

Below is the disk information showing that our initial setup only has the one 20gb disk currently, which is under the logical volume named /dev/mapper/Mega-root – this is what we will be expanding with the new disk.


Note that /dev/mapper/Mega-root is the volume made up from /dev/sda5 currently – this is what we will be expanding.

Adding a new virtual hard disk

First off we add a new disk to the virtual machine. This is done by right clicking the virtual machine in vSphere, selecting edit settings and then clicking the “Add…” button which is used to add hardware to the virtual machine.

Select hard disk and click next.



Select create a new virtual disk and click next.



Select the disk size you want to add, I will be using 20gb as previously mentioned. I have also selected to store the disk with the virtual machine, it will store on the same datastore as the virtual machines files, this will be fine for my test purposes. Click next once complete.



Select next on the advanced options page.



Review everything and click finish once you have confirmed the settings.



You will then see the new disk under the hardware devices tab and it will be labelled with (adding) which means it will not apply until you click OK, so click OK to complete the process.



Detect the new disk space

In my test for this example, as soon as I added the additional disk in through VMware it displayed through “fdisk -l” for me, you can see the second disk labelled /dev/sdb (I have cropped out the information on /dev/sda1 to make it less cluttered here). It is also worth noting that it shows as not containing a valid partition table, we are about to set this up.



This may not however be the case for you, to avoid reboot you may need to rescan your devices, you can try this with the below command. Note that you may need to change host0 depending on your setup.

echo "- - -" > /sys/class/scsi_host/host0/scan

If you have issues detecting the new disk, just perform a reboot and it should then display correctly.

Partition the new disk

We now need to partition the new /dev/sdb disk so that it can be used, this is done by using fdisk.

fdisk /dev/sdb

This should provide us with the below prompt, the inputs I have entered in are shown in bold.

‘n’ was selected for adding a new partition.

root@Mega:~# fdisk /dev/sdb
Command (m for help): n

‘p’ is then selected as we are making a primary partition.

Command action
   e   extended
   p   primary partition (1-4)

As this is a new disk, we do not yet have any partitions on it so we will use partition 1 here.

Partition number (1-4): 1

Next we press the enter key twice, as by default the first and last cylinders of the unallocated space should be correct.

First cylinder (1-2610, default 1): "enter"
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610): "enter"
Using default value 2610

‘t’ is selected to change to a partitions system ID, in this case we change to ’1′ automatically as this is currently our only partition.

Command (m for help): t
Selected partition 1

The hex code ’8e’ was entered as this is the code for a Linux LVM which is what we want this partition to be, as we will be joining it with the original Linux LVM which is currently using /dev/sda5.

Hex code (type L to list codes): 8e
Changed system type of partition 1 to 8e (Linux LVM)

‘w’ is used to write the table to disk and exit, all changes that have been done will be saved and then you will be exited from fdisk.

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

By using “fdisk -l” now you will be able to see that /dev/sdb1 is listed, this is the new partition created on our newly added /dev/sdb disk and it is currently using all 20gb of space.


Increasing the logical volume

Next we will use the pvcreate command to create a physical volume for later use by the LVM. In this case the physical volume will be our new /dev/sdb1 partition.

root@Mega:~# pvcreate /dev/sdb1
  Physical volume "/dev/sdb1" successfully created

Now we need to confirm the name of the current volume group using the vgdisplay command. The name will vary depending on your setup, for me it is the name of my test server. vgdisplay provides plenty of information on the volume group, I have only shown the name and the current size of it for this example.

root@Mega:~# vgdisplay
  --- Volume group ---
  VG Name               Mega
  VG Size               19.76 GiB

Now using the vgextend command, we extend the ‘Mega’ volume group by adding in the physical volume of /dev/sdb1 which we created using the pvcreate command just before.

root@Mega:~# vgextend Mega /dev/sdb1
  Volume group "Mega" successfully extended

Using the pvscan command we scan all disks for physical volumes, this should confirm the original /dev/sda5 partition and the newly created physical volume /dev/sdb1

root@Mega:~# pvscan
  PV /dev/sda5   VG Mega   lvm2 [19.76 GiB / 0    free]
  PV /dev/sdb1   VG Mega   lvm2 [19.99 GiB / 19.99 GiB free]
  Total: 2 [39.75 GiB] / in use: 2 [39.75 GiB] / in no VG: 0 [0   ]

Next we need to increase the logical volume with the lvextend command (rather than the physical volume which we have already done). This means we will be taking our original logical volume and extending it over our new disk/partition/physical volume of /dev/sdb1.

Firstly confirm the name of the logical volume using lvdisplay. The name will vary depending on your setup.

root@Mega:~# lvdisplay
  --- Logical volume ---
  LV Name                /dev/Mega/root
  LV Size                18.91 GiB

The logical volume is then extended using the lvextend command. We are extending the original logical volume of /dev/Mega/root over the newer /dev/sdb1

root@Mega:~# lvextend /dev/Mega/root /dev/sdb1
  Extending logical volume root to 38.90 GiB
  Logical volume root successfully resized

If you like you can then run vgdisplay and lvdisplay again to confirm the size of the volume group and logical volume respectively, I have done this and I now have the following.

  LV Size                38.90 GiB
  VG Size                39.75 GiB

However if you run a “df” command to see available disk space it will not have changed yet as there is one final step, we need to resize the file system using the resize2fs command in order to make use of this space.

root@Mega:~# resize2fs /dev/Mega/root
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/Mega/root is mounted on /; on-line resizing required
old desc_blocks = 2, new_desc_blocks = 3
Performing an on-line resize of /dev/Mega/root to 10196992 (4k) blocks.
The filesystem on /dev/Mega/root is now 10196992 blocks long.

This took a minute or so to complete, running the “df” command now shows the correct disk space for /dev/mapper/Mega-root