Operating Systems
Where is my second CPU gone in Linux
Sep 8th
This was a weird problem that I faced when I installed Fedora 12 on my Intel 2140 Dual Core pc. The installtion went fine and Linux was working properly. But I discovered that Linux did not actually detect second CPU core when I examined /proc/cpuinfo. Earler I had used Fedora 10 which detected both the cores properly and worked well.
After doing some googling in the Internet, I found that Fedora 12 had disabled SMP mode during boot up and the problem can be rectified by placing “noapic acpi=off” in the Linux kernel command line options. Hmm.. The solution did work. More >
How to know when my password is going to expire in Linux
Sep 7th
Typically organizations implement periodic password expire policy to harden the security. If you want to know when your password is going to expire by yourself, the command “chage” can give you the information. This command is actually meant for super user (root user). However a normal will be able to retrieve information about himself if not about other users.
Use the following command to information about your password.
[neo@techpulp ~]# chage -l neo Last password change : Jun 20, 2010 Password expires : never Password inactive : never Account expires : never Minimum number of days between password change : 0 Maximum More >
How to bind my mysql server to a specific IP address
Sep 6th
MySQL server contains a file my.cnf in /etc direcory of Linux. This file contains configuration of MySQL server as well as the configuration parameters of the MySQL client.
To make MySQL server listen on a specific IP address, you need to add a line similar to the following with IP address of your choice under mysqld section.
[root@techpulp ~]# cat /etc/my.cnf [mysqld] datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock user=mysql # Default to using old password format for compatibility with mysql 3.x # clients (those using the mysqlclient10 compatibility package). old_passwords=1 # To allow mysqld to connect to a MySQL Cluster management daemon, uncomment # these lines More >
How to lock and unlock an user account in FreeBSD
Sep 5th
Any user account can be locked or unlocked only by Administrator (i.e root user). This is done using pw command as explained below.
To lock a user account (mark) from logging in:
[root@techpulp ~]# pw lock mark
To unlock a user account (mark):
[root@techpulp ~]# pw unlock mark
How to check status of password for an account in Linux
Sep 4th
The need to check the status of password for an account comes if you have a habit of locking user account based on certain criteria. In another scenario, if have received requests from employees that have their user accounts expired. This scenario occurs if you have an Organization policy of locking user account for certain number of sequential login failures or if an account is unused for certain period.
To check the status of password of an account, you need to use “passwd” command as shown below.
[root@techpulp ~]# passwd -S mark mark PS 2009-01-21 0 99999 7 -1 (Password set, unknown More >
How to read Microsoft Windows .chm help files in Linux
Sep 2nd
It is sometimes required to read Microsoft Windows help files (.chm) in Linux. Once such case could be for cross developing applications using MinGW for Windows in Linux. Another case could be reading documentation of a generic stuff like JavaScript programming etc.
Linux supports a command called “xchm” that can be used to view .chm files. You can install it using “yum” command in Fedora/RHEL Linux as shown below.
[root@techpulp ~]# yum -y install xchm
After successful installation you should see a new command xchm available.
To open a .chm help file, use following command.
[neo@techpulp ~]# xchm jquery.chm
There’s a KDE version of CHM file viewer More >
How to create passwordless account in Linux system
Sep 1st
First of all, you should know that creating a password-less account is a very bad idea. You should be knowing what you are doing before doing so. However this may be of use in certain scenarios like doing SSH or Telnet to a virtual machines created using Virtualization software like VMWare, KVM, Microsoft Virtual PC etc. In such scenarios you should have a dedicated network adapter for each virtual machine that is accessible to the host machine only. Of course any such management service like SSH, Telnet or FTP should be running only on the adapter accessible to Host system More >
How to install screen command in FreeBSD
Sep 1st
To install screen command in FreeBSD, run the following commands after logging in as super user (root). Note that you should have valid Internet connection.
[root@techpulp ~]# cd /usr/ports/sysutils/screen [root@techpulp ~]# make install
The above command should download screen command from FreeBSD repository and install it in your system.
How to unzip files with .7z extension in Fedora Linux
Aug 31st
There is an open source tool named 7zip which creates compressed files with .7z extension. Fedora Linux provides a package in its repository to install the application. First of all, you need to install “p7zip” package in the system as shown below. You need to login as root and the system should have an active Internet connection so that “yum” tool can download from Fedora repository to install 7zip in your system.
[root@techpulp ~]# yum -y install p7zip
If installation is successful, you should see a command with name “7za“.
You can the command 7za to uncompress a file with .7z extension as More >
How to show desktop pop-up notification in Linux using notify-send command
Aug 27th
It is very useful when you are about to start a bulk job and want to get notified asynchronously after its completion. That helps you continue with other work without having to check for its completion periodically. Of course if you don’t have any other work, you can at least play few games without bothering about the job completion.
There is a command in Linux called “notify-send” that can be used to generate a desktop notification from command line or a script. However where exactly this notification message appears depends entirely on the desktop you are using. For example, if you More >
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