How to install NFS (Network File System) server in Linux Mint?

The Network File System (NFS) protocol was developed by Sun Microsystems in 19841. NFS builds over Open Network Computing Remote Procedure Call, commonly called SUN ONC.

Step 1: Install NFS server and associated applications on the Linux Mint desktop.

Issue the command: #sudo apt-get install nfs-kernel-server nfs-common portmap

Step 2: Configure the NFS Server.

NFS exports from a server are controlled by the file /etc/exports. Each line begins with the absolute path of a directory to be exported, followed by a space-seperated list of allowed clients.

For example: To export the /var/nfs directory so that it can be accessed by any client, please insert the below line into /etc/export.
/var/nfs * (ro,async,subtree_check)

Note: Allowing any client to access your box can be potentially harmful. Please reconsider your decision before doing so.

To allow access to machines with a particular set of IP addresses, please insert the below line in /etc/export.
/var/nfs 192.168.1.1/24 (ro,async,subtree_check)

Other options that can specified along with the IP address include:

ro:

The directory is shared read only; the client machine will not be able to write it. This is the default.

rw:

The client machine will have read and write access to the directory.

no_root_squash:

If no_root_squash is specified, then root on the client machine will have the same level of access to the files on the system as root on the server. This can have serious security implications. You should not specify this option without a good reason.

no_subtree_check:

If only part of a volume is exported, a routine called subtree checking verifies that a file that is requested from the client is in the appropriate part of the volume. If the entire volume is exported, disabling this check will speed up transfers.

sync

By default, all but the most recent version (version 1.11) of the exportfs command will use async behavior, telling a client machine that a file write is complete – that is, has been written to stable storage – when NFS has finished handing the write over to the filesystem. This behavior may cause data corruption if the server reboots, and the sync option prevents this.

References


1.  “Design and Implementation of the Sun Network Filesystem“. USENIX. 1985.

2. RFC 3530 – NFS Version 4 Protocol Specification.

3. Linux NFS Overview, FAQ and How-To documents.

Disclaimer


All data and information provided on this site is for informational purposes only. sks8.wordpress.com or skumar.co.nr makes no representations as to accuracy, completeness, currentness, suitability, or validity of any information on this site and will not be liable for any errors, omissions, or delays in this information or any losses, injuries, or damages arising from its display or use. All information is provided on an as-is basis. Any trademarks, if at all displayed on this blog belong to their respective owners.

a user on a client computer to access files over a network in a manner similar to how local storage is accessed
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How to reset forgotten root password in Linux?

The root password for the Linux system can be reset by booting it into the Single User mode which is also termed as Emergency mode or more popularly known as Rescue mode.

If the boot loader installed on your Linux system is GRUB, then please follow the below listed steps to reset the root password.

  • Select the line which specifies the kernel to be loaded.
  • Press the ‘e’ key to edit the entry.
  • Choose second line (the line starting with the word kernel).
  • Press the ‘e’ key again to edit kernel entry
  • Append the letter ‘S’ or word ‘single’ to the end of the line.
  • Press the [ENTER] key
  • Press the ‘b’ key to boot the Linux kernel into single user mode

After the booting process completes, mount the ‘/’ and ‘proc’ partitions using the below listed commands.

# mount -t proc proc /proc
# mount -o remount,rw /

Issue the 'passwd' command to change the root password.

Finally, reboot the system employing the below commands.
# sync
# reboot

If the boot loader installed on your Linux system is not GRUB but LILO, then please follow the below mentioned steps to reset the root password.

  • At the Boot: prompt displayed by the LILO boot loader, type linux single and press the [ENTER] key:
  • Allow the system boot and when it displays the # prompt, type passwd to reset the root password.
  • Finally, reboot the system by issuing sync followed by the reboot command.

Disclaimer

All data and information provided on this site is for informational purposes only. sks8.wordpress.com or skumar.co.nr makes no representations as to accuracy, completeness, currentness, suitability, or validity of any information on this site and will not be liable for any errors, omissions, or delays in this information or any losses, injuries, or damages arising from its display or use. All information is provided on an as-is basis. Any trademarks, if at all displayed on this blog belong to their respective owners.

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What is the difference between exit() and _exit() system call?

Should I employ exit(int status) or _exit(int status) to exit() from a child process? Does this question haunt you quite often? If so, this post is for you.

The exit() method which is part of the C library routines calls the kernel system call _exit() internally.

The responsibility of the kernel system call _exit() includes asking the kernel to close any open descriptors, free the memory used by the process and perform terminating process clean-up. Whereas the exit() call takes care of flushing the I/O buffers and perform additional clean-up before invoking _exit() internally.

In simpler words, exit() performs clean-up related to user-mode constructs in the library, and calls user-supplied cleanup functions whereas _exit() performs only the kernel level cleanup for the process.

It’s always advisable to use _exit(int status) in a child because employing exit(int status) can lead to stdio buffers being flushed twice, and temporary files being unexpectedly removed.

Finally, exit(int status) is defined in stdio.h and _exit(int status) is defined in unistd.h file.

Disclaimer

All data and information provided on this site is for informational purposes only. sks8.wordpress.com or skumar.co.nr makes no representations as to accuracy, completeness, currentness, suitability, or validity of any information on this site and will not be liable for any errors, omissions, or delays in this information or any losses, injuries, or damages arising from its display or use. All information is provided on an as-is basis. Any trademarks, if at all displayed on this blog belong to their respective owners.

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How to obtain hostname from IP address in Linux?

Today, I fell in need of identifying the host name (also termed as ‘DNS name‘) based on the IP address for one of my Linux Box. My first try was using 'ping -a' command. But that failed to satisfy my requirement.

Domain names, arranged in a tree, cut into zon...
Image via Wikipedia

If you ever come across the situation where 'ping -a' does not provide you with the host name of the box, then you can try any of the below mentioned methods to satisfy the requirement.

Method 1: Using the 'host' command

One of the simplest way to retrieve host name from IP address is employing the 'host' command provided by GNU/Linux.
Syntax for the host command: $>host <ip-address> <nameserver>
Example:

testhost:~ # host 209.85.231.104
104.231.85.209.in-addr.arpa domain name pointer maa03s01-in-f104.google.com.
testhost:~ #

Method 2: Using the 'nslookup' command

nslookup is a command used to query the Internet Domain Name servers.

Example:
nslookup 209.85.231.104
Server:  72.163.128.140
Address: 72.163.128.140#53


Non-authoritative answer:
104.231.85.209.in-addr.arpa    name = maa03s01-in-f104.google.com.


Authoritative answers can be found from:
231.85.209.in-addr.arpa    nameserver = ns1.google.com.
231.85.209.in-addr.arpa    nameserver = ns3.google.com.
231.85.209.in-addr.arpa    nameserver = ns4.google.com.
231.85.209.in-addr.arpa    nameserver = ns2.google.com.
ns3.google.com    internet address = 216.239.36.10
ns4.google.com    internet address = 216.239.38.10
ns2.google.com    internet address = 216.239.34.10
ns1.google.com    internet address = 216.239.32.10

Method 3: Using the 'dig' command
As per the Linux man pagedig (domain information groper) is a flexible tool for interrogating DNS name servers. It performs DNS lookups and displays the answers that are returned from the name server(s) that were queried.

Disclaimer

All data and information provided on this site is for informational purposes only. sks8.wordpress.com or skumar.co.nr makes no representations as to accuracy, completeness, currentness, suitability, or validity of any information on this site and will not be liable for any errors, omissions, or delays in this information or any losses, injuries, or damages arising from its display or use. All information is provided on an as-is basis. Any trademarks, if at all displayed on this blog belong to their respective owners.

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My most favourite Linux wallpapers – Series 1

I am a die hard fan of Linux (though I am writing this blog using a Microsoft® Windows box). It a great operating system where a user is allowed to customize anything straight down to the code level.

I have been using Linux for the past nine years intermittently. Most of the time, it has been only to satisfy my urge to create software.

All these years, I have had used a lot of wallpapers to decorate my desktop. Both of my Linux as well as Microsoft® Windows desktops. I like a couple of wallpapers that I think would be a good idea to share with the rest of the world.

1. Linux Mint – Water Droplets

Linux Mint - Green Water Droplets

This is my most favourite wallpaper. This decorates my desktop at present.

This wallpaper was created by Zwopper. It licensed under Creative Commons.

2. Linux Mint – Blue – Water Droplets

Linux Mint - Blue Water Droplets

This wallpaper that always revitalizes me!

This wallpaper was created by Zwopper. It licensed under Creative Commons.

3. Linux Mint – Blueness

Linux Mint Blueness

An eye pleasing wallpaper!

This wallpaper was created by Nikola Trifunovic. It licensed under GPL.

4. Linux Mint – Light Green

Linux Mint - Light Green

It looks good on Desktop

This wallpaper was created by Zwopper. It licensed under Creative Commons.

5. Linux Mint – Dark Blue

Linux Mint - Dark Blue

Imparts soothing effect on your thoughts when on desktop

This wallpaper was the winner of the ‘Wallpaper of the Month, August 2008‘ in the Mint Wallpaper contest. It’ licensed under GPL.

6. Linux Mint – Dark Green

Linux Mint - Dark Green

Green is considered to be one of the most pleasing colours!

This is the Linux Mint Daryna Wallpaper.

Disclaimer:

All data and information provided on this site is for informational purposes only. sks8.wordpress.com nor skumar.co.nr makes no representations as to accuracy, completeness, currentness, suitability, or validity of any information on this site and will not be liable for any errors, omissions, or delays in this information or any losses, injuries, or damages arising from its display or use. All information is provided on an as-is basis. The trademarks, if at all used on this blog belong to their respective owners.

Published in: on August 14, 2009 at 12:44 pm  Comments (5)  
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