Linux how to

Practical instructions on how to go about doing things in Linux. This is about the Fedora Linux.

How to extend an xfs filesystem

• xfs filesystems must be mounted to be extended. There is no need to unmount
• usually an xfs fileystem occupies all of its logical volume so the extension of a filesytem involves first the expansion of the logical volume and then the extension of the filesystem

• expanding the logical volume

• lvextend -L +5G /dev/Volume00/data-lv00 - this will add 5GB on logical voluem /dev/Volume00/data-lv00
• xfs_growfs /NewFS - this will extend the filesystems on the previously extended LV to occupy it completely. The filesystem is mounted on /NewFS in this case.

More on how to operate the Logical Volume Manager (LVM) is found here

How to extend an ext3 file system

Note: A mounted ext3 file system cannot be extended. Unmount it before proceeding.

• Unmount the file system
• expand the logical volume containing the file system

• lvextend -L +2G /dev/Volume00/lvol00 - this will add 2GB on logical volume /dev/Volume00/lvol00

• do an fsck on the file system (this is required)

• e2fsck /dev/Volume00/lvol00

• extend the filesystem to the logical volume limits

• resize2fs /dev/Volume00/lvol00

• remount file system

How to install java

• 1. Download the latest JDK version from Sun. Choose the "Linux self-extracting file" version (not the RPM version).
• 2. Make sure the "rpm-build" package is installed:

 yum install rpm-build

• 3. Move the JDK to the RPM Building Source directory:

 mv jdk-* /usr/src/redhat/SOURCES/

• 4. Download the Source RPM from JPackage. Make sure you choose the same version as the JDK you downloaded in step 1.
• 5. Build the Java RPM using the file that you just downloaded:

 rpmbuild --rebuild java-*src.rpm

• 6. After the build the RPMs can be found in /usr/src/redhat/RPMS/i586/. You can install them using yum:

 yum -y localinstall /usr/src/redhat/RPMS/i586/java-1.5.0-sun-*

• 7. If you want to enable the Java plugin for your web browser do the following:

 ln -s $JAVA_HOME/jre/plugin/i386/ns7/libjavaplugin_oji.so /usr/lib/mozilla/plugins/

• 8. Make sure that the old X11 libraries are installed, or Java will crash your web browser:

 yum install xorg-x11-deprecated-libs

How to install Flash plugin

• Setup Macromedia yum repository by editing the /etc/yum.repos.d/macromedia.repo file:

 [macromedia]
 name=Macromedia for i386 Linux
 baseurl=http://macromedia.rediris.es/rpm/
 enabled=1
 gpgcheck=1
 gpgkey=http://macromedia.mplug.org/FEDORA-GPG-KEY

• Install the plugin using yum:

 yum -y install flash-plugin

• Note: If the Macromedia license agreement does not appear you may have to run /usr/lib/flash-plugin/setup install. At the time of this writing there is a bug in Flash plugin that prevents it from displaying normal text in FC5. To resolve this follow the instructions describe at Macromedia's FAQ.

How to sign your RPM packages with GPG Key

1. Generate your own gpg key pair. For more information have a look at FedoraNEWS.ORG
2. Use rpm command as shown below to sign your packages

 rpm --addsign file_name.rpm

If the file is already signed, then you can use --resign option to sign it with your signature. To check signatures, simply use --checksig option