Start and stop VMWARE VPS / virtual machine guest operating system from command line

Posted on in Categories Howto, Linux, Linux distribution, RedHat/Fedora Linux, Sys admin, Tips last updated June 30, 2007

Vmware server comes with the nifty vmware-cmd utility. It allows an administrator to perform various operations on a virtual machine from Linux command line / shell prompt such as:

=> Stop / Start VM

=> Get VM status

=> Setup variables

=> Powerdown VM and much more

Task: Lists the virtual machines on the local server

You can list all servers and config file, enter:
# vmware-cmd -l
Output:

/nas/vms/Ubuntu/Ubuntu.vmx
/nas/vms/FreeBSD/FreeBSD.vmx
/nas/vms/OpenBSD/OpenBSD.vmx
/nas/vms/Debian4/Debian4.vmx
/nas/vms/CentOS5/CentOS5.vmx

Turn on VM / Power up VPS

Just pas start option to vmware-cmd,
# vmware-cmd /nas/vms/FreeBSD/FreeBSD.vmx start

To stop VM/VPS, enter:
# vmware-cmd /nas/vms/FreeBSD/FreeBSD.vmx stop

To reset VM/VPS, enter:
# vmware-cmd /nas/vms/FreeBSD/FreeBSD.vmx reset

To suspend VM/VPS, enter:
# vmware-cmd /nas/vms/FreeBSD/FreeBSD.vmx suspend

Find out if OpenBSD VM is on or off:
# vmware-cmd /disk2.vmware/vms/OpenBSD/OpenBSD.vmx getstate
Output:

getstate() = off

vmware-cmd offers other options, please consult VMWARE documentation for more information.

Download Linux Google desktop application

Posted on in Categories Download of the day, Linux desktop, Linux distribution, RedHat/Fedora Linux, Ubuntu Linux last updated June 28, 2007

Google Desktop is a desktop search application that gives you easy access to information on your computer and from the web. Desktop makes searching your own email, files, music, photos, and more as easy as searching the web with Google.

Earlier this application was only available on Windows or Mac system. Now google released Linux version. This is done almost three years after the product’s launch for the Windows operating system.

=> Search your computer as easily as you search the web with Google

=> Find information in your documents, emails, web history, and more

=> Open files with just a few keystrokes

Google Desktop for Linux runs on Debian 4.0, Fedora Core 6, Ubuntu 6.10, SUSE 10.1, and Red Flag 5.

On a related note if privacy is a big concern try old good find command or Linux GUI desktop search application.

Download Linux Google Desktop

Red Hat and Canonical (Ubuntu) rejected any patent deals with Microsoft

Posted on in Categories GNU/Open source, Linux, Linux desktop, Linux distribution, News, Windows last updated June 20, 2007

This is really good news. Both Redhat and Canonical (Ubuntu’s parent company) has rejected nasty Microsoft patent deals.

Following Linux distributions and companies made a patent deals with Microsoft:
[a] Novell Suse Linux
[b] Linspire Linux desktop
[c] Xandros Linux desktop
[d] LG Electronics

The drama started last November, when Microsoft inked a deal with Novell to foster interoperability and technical collaboration between the open- and closed-source operating systems. Novell also got protection from possible patent suits as part of the agreement.

Soon after, Microsoft came out with allegations that the open-source camp is infringing on 235 of its patents, and the software giant began making moves to form alliances with other Linux providers. The company was successful in negotiating partnerships with Xandros and Linspire, but has hit a wall with Ubuntu and Red Hat.

Canonical chief executive Mark Shuttleworth has made it clear that Ubuntu isn’t interested in forming a deal with Microsoft along the lines of those recently reached by Linspire, Xandros and Novell.

Red Hat Says No to Microsoft ‘Innovation Tax’

nixCraft FAQ Roundup June 07, 2007

Posted on in Categories FAQ last updated June 7, 2007

Recently updated/posted Linux and UNIX FAQ (mostly useful to Linux/UNIX new administrators or users) :

Enjoy!

Howto Reboot or halt Linux system in emergency

Posted on in Categories CentOS, Debian Linux, Gentoo Linux, Howto, Linux, Linux distribution, Networking, RedHat/Fedora Linux, Security, Suse Linux, Sys admin, Tips, Troubleshooting, Ubuntu Linux last updated August 25, 2005

Linux kernel includes magic system request keys. It was originally developed for kernel hackers. However, you can use this hack to reboot, shutdown or halt computer safely (remember safe reboot/shutdown == flush filesystem buffers and unmount file system and then reboot so that data loss can be avoided).

This is quite useful when Linux based system is not available after boot or after a X server crashed ( svgalib program crashes) or no display on screen. Sysrq key combo forces the kernel to respond it regardless of whatever else it is doing, unless it is completely locked up (dead).

Using further extension to iptables called ipt_sysrq (new iptables target), which allows you to do the same as the magic sysrq key on a keyboard does, but over the network. So if your network server is not responding you can still reboot it. Please note that Magic SysRq support need to be compiled in your kernel. You need to say “yes” to ‘Magic SysRq key (CONFIG_MAGIC_SYSRQ)’ when configuring the kernel. I’m assuming that you have Magic SysRq key’ support is compiled in your kernel.

Enable sysrq keys

By default it is not enabled on many Linux distributions. Add or modify following line (as soon as new Linux system installed) /etc/sysctl.conf:
# vi /etc/sysctl.conf
Append following config directive:
kernel.sysrq=1
Save and close the file. Reload settings:
# sysctl -p

Save and close the file and reboot system to take effect

How do I use the magic SysRq keys in emergency?

You need to use following key combination in order to reboot/halt/sync file system etc:
ALT+SysRq+COMMAND-KEY

The ‘SysRq’ key is also known as the ‘Print Screen’ key. COMMAND-KEY can be any one of the following (all keys need to hit simultaneously) :

  • ‘b’ : Will immediately reboot the system without syncing or unmounting your disks.
  • ‘o’ : Will shutdown your system off (if configured and supported).
  • ‘s’: Will attempt to sync all mounted filesystems.
  • ‘u’ : Will attempt to remount all mounted filesystems read-only.
  • ‘e’ : Send a SIGTERM to all processes, except for init.
  • ‘h’: Show help, indeed this the one you need to remember.

So whey you need to tell your Linux computer to reboot or when your X server is crashed or you don’t see anything going across the screen then just press:

ALT+SysRQ+s : (Press and hold down ALT, then SysRQ (Print Screen) key and press ‘s’) -Will try to syn all mounted system

ALT+SysRQ+r : (Press and hold down ALT, then SysRQ (Print Screen) key and press ‘r’) -Will reboot the system.

If you wish to shutdown the system instead of reboot then press following key combination:
ALT+SysRQ+o

ipt_sysrq is a new iptables target that allows you to do the same as the magic sysrq key on a keyboard does, but over the network. Sometimes a remote server hangs and only responds to icmp echo request (ping). Every administrator of such machine is very unhappy because (s)he must go there and press the reset button. It takes a long time and it’s inconvenient. So use the Network Magic SysRq and you will be able to do more than just pressing a reset button. You can remotely sync disks, remount them read-only, then do a reboot. And everything comfortably and only in a few seconds. Please see Marek Zelem page to enableIP Tables network magic SysRq function.

For more information read official Documentation for sysrq.c version 1.15 stored in /usr/src/linux/Documentation/sysrq.txt and read man page of sysctl, sysctl.conf.

Linux : How to delete file securely

Posted on in Categories File system, Gentoo Linux, Linux, RedHat/Fedora Linux, Security, Suse Linux, Sys admin, Tips, Ubuntu Linux last updated June 22, 2005

Recently we had lot of discussion regarding this issue. How to remove files securely so that it cannot be undeleted. Peter Gutmann paper “Secure Deletion of Data from Magnetic and Solid-State Memory” has very good information. Here are some commands/tools available under Debian GNU/Linux (it should work with other Linux distributions) to delete file securely.

srm: Securely remove files or directories

This command is a replacement for rm command. It works under Linux/BSD/UNIX-like OSes. It removes each specified file by overwriting, renaming, and truncating it before unlinking. This prevents other people from undelete or recovering any information about the file from the command line. Because it does lots of operation on file/directory for secure deletion, it also takes lot of time to remove it. Download srm from http://sourceforge.net/projects/srm (RPM file is also available for RPM based Linux distributions)

i) Untar and install the srm:

# ./configure
# make
# make install 

ii) How to use srm?
srm syntax is like rm command. Read man srm. Here is simple example:

$ srm privateinfo.doc

wipe: It is a secure file wiping utility

Download wipe from http://wipe.sourceforge.net/
i) Untar and install the wipe

# ./configure
# make
# make install

ii) How to use wipe?

$ wipe filename

Read man page of wipe for information.

shred: Delete a file securely, first overwriting it to hide its contents.

It is available on most of Linux distributions including Debian GNU/Linux. To remove file called personalinfo.tar.gz :

$ shred -n 200 -z -u  personalinfo.tar.gz

Where,

  • -n: Overwrite N (200) times instead of the default (25)
  • -z: Add a final overwrite with zeros to hide shreddin
  • -u: Truncate and remove file after overwriting

Read the man page of shred(1) for more information. Most of these utilities are not effective (read as useless) only if :

  • File system is log-structured or journaled filesystems, such as JFS, ReiserFS, XFS, Ext3 etc
  • Your filesystems is RAID-based, compressed filesystem etc
  • In addition, file system backups and remote mirrors may contain copies of the file that cannot be removed by these utilities.

See also: