zswap – compcache, compressed swap for better performance

First, here is a link to article on compcache.

http://code.google.com/p/compcache/wiki/CompilingAndUsingNew

zswap is already in the kernel and you can see the documentation in the kernel documentation. Here is the name of the file if you need:

/usr/share/doc/kernel-doc-$(uname -r)/Documentation/vm/zswap.txt

Here is the overview, in case you do not want to install kernel-doc

Overview:

Zswap is a lightweight compressed cache for swap pages. It takes pages that are
in the process of being swapped out and attempts to compress them into a
dynamically allocated RAM-based memory pool.  zswap basically trades CPU cycles
for potentially reduced swap I/O.  This trade-off can also result in a
significant performance improvement if reads from the compressed cache are
faster than reads from a swap device.

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cvs add files recursively – not already in repository

When you have a lot of files in some repository and you have added a couple of new, in CVS there is no command to add just the new ones to the repository, so here is a workaround for that.

cvs status 2>/dev/null | awk '{if ($1=="?")print "cvs add -kb " $2}'

Well, if you are adding text files then you might want to remove the “-kB” in the cvs command above.

Code beautifier for php

If you would like to beautify your php scripts, then you can use the beautifier available at :

http://pear.php.net/package/PHP_Beautifier/download

Home grown mail scheduler with bash script and cron

If you are using Linux (Fedora/Ubuntu or anything else) then you do get a lot of tools and one of them is cron. Very very useful. Just write some script that can do the task for you, put it in cron and forget it. So, here is a home grown way to schedule mails.

First, copy this script below:

#!/bin/bash -
#===============================================================================
#
#          FILE: sched_mail.sh
#
#         USAGE: ./sched_mail.sh
#
#   DESCRIPTION:
#
#       OPTIONS: ---
#  REQUIREMENTS: ---
#          BUGS: ---
#         NOTES: ---
#        AUTHOR: Amit Agarwal (aka), 
#      REVISION:  ---
#===============================================================================

mailfile="~/mail"
if [[ $(wc -l $mailfile|awk '{print $1}' ) -ge 5 ]]
then
    to=$(grep ^To: $mailfile|sed 's/To: //')
    echo "Good to send mail... to = $to"
    sendmail -t <$mailfile
    echo "once mail is send, delete the contents of file"
    echo "sed -i '4,$ d' $mailfile"
fi

Now, create a file called mail in your home directory, with the following contents:

force recheck on reboot – fsck

If you want to force a fsck re-check on reboot, then just

touch /forcefsck

Related articles

• Set some disk params to be safe
• Improve Boot Performance
• Ext4

find more information on ext2/3/4 filesystem

In my previous post on check filesystem regurlarly, I mentioned tune2fs. That tool give quite a lot of information. But just in case, you did not find what you are looking for in the output, then you can get much more information on these partitions with the dumpe2fs command.

findmnt – find all the mounts and their source

If you are looking for the source of a mount and the various options used in the mount, then the quickest way to get that is ::

findmnt

By default, with no parameters, it lists all the mounts in a tree like view and all the options used to mount the path. It also lists the source of the mount.

By default again, it uses some capabilities of the terminal to show the tree which you can disable with the option “-a”.