Linux Tips and Stuff

Application failed to initialize 0xc0000135 Google Chrome known issue

noreply@blogger.com (derrick caluag) — Wed, 10 Sep 2008 09:17:00 +0000

If you happened to encounter this error after installing Google Chrome on Windows XP / Vista "Application failed to initialize 0xc0000135". I have the solution.

1. Check if your PC have Microsoft .NET framework installed.

2. Disable any antivirus program especially Symantec before running the application then enable it again while chrome is running.

If this doesn't do the trick.. put a comment on this blog.. thanks..

AIX commands you should not leave home without

noreply@blogger.com (derrick caluag) — Thu, 31 Jan 2008 03:15:00 +0000

Introduction

As you know, AIX® has a vast array of commands that enable you to do a multitude of tasks. Depending on what you need to accomplish, you use only a certain subset of these commands. These subsets differ from user to user and from need to need. However, there are a few core commands that you commonly use. You need these commands either to answer your own questions or to provide answers to the queries of the support professionals.

In this article, I'll discuss some of these core commands. The intent is to provide a list that you can use as a ready reference. While the behavior of these commands should be identical in all releases of AIX, they have been only tested under AIX 5.3.

Note:
The bootinfo command discussed in the following paragraphs is NOT a user-level command and is NOT supported in AIX 4.2 or later.

Commands

Kernel

How would I know if I am running a 32-bit kernel or 64-bit kernel?

To display if the kernel is 32-bit enabled or 64-bit enabled, type:

bootinfo -K

How do I know if I am running a uniprocessor kernel or a multiprocessor kernel?

/unix is a symbolic link to the booted kernel. To find out what kernel mode is running, enter ls -l /unix and see what file /unix it links to. The following are the three possible outputs from the ls -l /unix command and their corresponding kernels:

/unix -> /usr/lib/boot/unix_up   # 32 bit uniprocessor kernel
/unix -> /usr/lib/boot/unix_mp   # 32 bit multiprocessor kernel
/unix -> /usr/lib/boot/unix_64   # 64 bit multiprocessor kernel

Note:
AIX 5L Version 5.3 does not support a uniprocessor kernel.

How can I change from one kernel mode to another?

During the installation process, one of the kernels, appropriate for the AIX version and the hardware in operation, is enabled by default. Let us use the method from the previous question and assume the 32-bit kernel is enabled. Let us also assume that you want to boot it up in the 64-bit kernel mode. This can be done by executing the following commands in sequence:

ln -sf /usr/lib/boot/unix_64    /unix
ln -sf /usr/lib/boot/unix_64    /usr/lib/boot/unix

bosboot -ad  /dev/hdiskxx
shutdown -r

The /dev/hdiskxx directory is where the boot logical volume /dev/hd5 is located. To find out what xx is in hdiskxx, run the following command:

 lslv -m hd5

Note:
In AIX 5.2, the 32-bit kernel is installed by default. In AIX 5.3, the 64-bit kernel is installed on 64-bit hardware and the 32-bit kernel is installed on 32-bit hardware by default.

Hardware

How would I know if my machine is capable of running AIX 5L Version 5.3?

AIX 5L Version 5.3 runs on all currently supported CHRP (Common Hardware Reference Platform)-based POWER hardware.

How would I know if my machine is CHRP-based?

Run the prtconf command. If it's a CHRP machine, the string chrp appears on the Model Architecture line.

How would I know if my System p machine (hardware) is 32-bit or 64-bit?

To display if the hardware is 32-bit or 64-bit, type:

bootinfo -y

How much real memory does my machine have?

To display real memory in kilobytes (KB), type one of the following:

bootinfo -r

lsattr -El sys0 -a realmem

Can my machine run the 64-bit kernel?

64-bit hardware is required to run the 64-bit kernel.

What are the values of attributes for devices in my system?

To list the current values of the attributes for the tape device, rmt0, type:

lsattr -l rmt0 -E

To list the default values of the attributes for the tape device, rmt0, type:

lsattr -l rmt0 -D

To list the possible values of the login attribute for the TTY device, tty0, type:

lsattr -l tty0 -a login -R

To display system level attributes, type:

lsattr -E -l sys0

How many processors does my system have?

To display the number of processors on your system, type:

lscfg | grep proc

How many hard disks does my system have and which ones are in use?

To display the number of hard disks on your system, type:

lspv

How do I list information about a specific physical volume?

To find details about hdisk1, for example, run the following command:

lspv hdisk1

How do I get a detailed configuration of my system?

Type the following:

lscfg

The following options provide specific information:

`-p`	Displays platform-specific device information. The flag is applicable to AIX 4.2.1 or later.
`-v`	Displays the VPD (Vital Product Database) found in the customized VPD object class.

For example, to display details about the tape drive, rmt0, type:

lscfg -vl rmt0

You can obtain very similar information by running the prtconf command.

How do I find out the chip type, system name, node name, model number, and so forth?

The uname command provides details about your system.

`uname -p`	Displays the chip type of the system. For example, PowerPC.
`uname -r`	Displays the release number of the operating system.
`uname -s`	Displays the system name. For example, AIX.
`uname -n`	Displays the name of the node.
`uname -a`	Displays the system name, nodename, version, machine ID.
`uname -M`	Displays the system model name. For example, IBM, 9114-275.
`uname -v`	Displays the operating system version.
`uname -m`	Displays the machine ID number of the hardware running the system.
`uname -u`	Displays the system ID number.

AIX

What version, release, and maintenance level of AIX is running on my system?

Type one of the following:

oslevel -r

lslpp -h bos.rte

How can I determine which fileset updates are missing from a particular AIX level?

To determine which fileset updates are missing from 5300-04, for example, run the following command:

oslevel -rl 5300-04

What SP (Service Pack) is installed on my system?

To see which SP is currently installed on the system, run the oslevel -s command. Sample output for an AIX 5L Version 5.3 system, with TL4, and SP2 installed would be:

oslevel –s
5300-04-02

Is a CSP (Concluding Service Pack) installed on my system?

To see if a CSP is currently installed on the system, run the oslevel -s command. Sample output for an AIX 5L Version 5.3 system, with TL3, and CSP installed would be:

oslevel –s
5300-03-CSP

How do I create a file system?

The following command will create, within volume group testvg, a jfs file system of 10MB with mounting point /fs1:

crfs -v jfs -g testvg -a size=10M -m /fs1

The following command will create, within volume group testvg, a jfs2 file system of 10MB with mounting point /fs2 and having read only permissions:

crfs -v jfs2 -g testvg -a size=10M -p ro -m /fs2

How do I change the size of a file system?

To increase the /usr file system size by 1000000 512-byte blocks, type:

chfs -a size=+1000000 /usr

Note:
In AIX 5.3, the size of a JFS2 file system can be shrunk as well.

How do I mount a CD?

Type the following:

mount -V cdrfs -o ro /dev/cd0  /cdrom

How do I mount a file system?

The following command will mount file system /dev/fslv02 on the /test directory:

mount /dev/fslv02 /test

How do I mount all default file systems (all standard file systems in the /etc/filesystems file marked by the mount=true attribute)?

The following command will mount all such file systems:

mount {-a|all}

How do I unmount a file system?

Type the following command to unmount /test file system:

umount /test

How do I display mounted file systems?

Type the following command to display information about all currently mounted file systems:

mount

How do I remove a file system?

Type the following command to remove the /test file system:

rmfs /test

How can I defragment a file system?

The defragfs command can be used to improve or report the status of contiguous space within a file system. For example, to defragment the file system /home, use the following command:

defragfs /home

Which fileset contains a particular binary?

To show bos.acct contains /usr/bin/vmstat, type:

lslpp -w /usr/bin/vmstat

Or to show bos.perf.tools contains /usr/bin/svmon, type:

which_fileset svmon

How do I display information about installed filesets on my system?

Type the following:

lslpp -l

How do I determine if all filesets of maintenance levels are installed on my system?

Type the following:

instfix -i | grep ML

How do I determine if a fix is installed on my system?

To determine if IY24043 is installed, type:

instfix -ik IY24043

How do I install an individual fix by APAR?

To install APAR IY73748 from /dev/cd0, for example, enter the command:

instfix -k IY73748 -d /dev/cd0

How do I verify if filesets have required prerequisites and are completely installed?

To show which filesets need to be installed or corrected, type:

lppchk -v

How do I get a dump of the header of the loader section and the symbol entries in symbolic representation?

Type the following:

dump -Htv

How do I determine the amount of paging space allocated and in use?

Type the following:

lsps -a

How do I increase a paging space?

You can use the chps -s command to dynamically increase the size of a paging space. For example, if you want to increase the size of hd6 with 3 logical partitions, you issue the following command:

chps -s 3 hd6

How do I reduce a paging space?

You can use the chps -d command to dynamically reduce the size of a paging space. For example, if you want to decrease the size of hd6 with four logical partitions, you issue the following command:

chps -d 4 hd6

How would I know if my system is capable of using Simultaneous Multi-threading (SMT)?

Your system is capable of SMT if it's a POWER5-based system running AIX 5L Version 5.3.

How would I know if SMT is enabled for my system?

If you run the smtctl command without any options, it tells you if it's enabled or not.

Is SMT supported for the 32-bit kernel?

Yes, SMT is supported for both 32-bit and 64-bit kernel.

How do I enable or disable SMT?

You can enable or disable SMT by running the smtctl command. The following is the syntax:

smtctl [ -m off | on [ -w boot | now]]

The following options are available:

`-m off`	Sets SMT mode to disabled.
`-m on`	Sets SMT mode to enabled.
`-w boot`	Makes the SMT mode change effective on next and subsequent reboots if you run the `bosboot` command before the next system reboot.
`-w now`	Makes the SMT mode change immediately but will not persist across reboot.

If neither the -w boot or the -w now options are specified, then the mode change is made immediately. It persists across subsequent reboots if you run the bosboot command before the next system reboot.

How do I get partition-specific information and statistics?

The lparstat command provides a report of partition information and utilization statistics. This command also provides a display of Hypervisor information.

Volume groups and logical volumes

How do I know if my volume group is normal, big, or scalable?

Run the lsvg command on the volume group and look at the value for MAX PVs. The value is 32 for normal, 128 for big, and 1024 for scalable volume group.

How to create a volume group?

Use the following command, where s partition_size sets the number of megabytes (MB) in each physical partition where the partition_size is expressed in units of MB from 1 through 1024. (It's 1 through 131072 for AIX 5.3.) The partition_size variable must be equal to a power of 2 (for example: 1, 2, 4, 8). The default value for standard and big volume groups is the lowest value to remain within the limitation of 1016 physical partitions per physical volume. The default value for scalable volume groups is the lowest value to accommodate 2040 physical partitions per physical volume.

mkvg -y name_of_volume_group -s partition_size list_of_hard_disks

How can I change the characteristics of a volume group?

You use the following command to change the characteristics of a volume group:

chvg

How do I create a logical volume?

Type the following:

mklv -y name_of_logical_volume name_of_volume_group number_of_partition

How do I increase the size of a logical volume?

To increase the size of the logical volume represented by the lv05 directory by three logical partitions, for example, type:

extendlv lv05 3

How do I display all logical volumes that are part of a volume group (for example, rootvg)?

You can display all logical volumes that are part of rootvg by typing the following command:

lsvg -l rootvg

How do I list information about logical volumes?

Run the following command to display information about the logical volume lv1:

lslv lv1

How do I remove a logical volume?

You can remove the logical volume lv7 by running the following command:

rmlv lv7

The rmlv command removes only the logical volume, but does not remove other entities, such as file systems or paging spaces that were using the logical volume.

How do I mirror a logical volume?

mklvcopy LogicalVolumeName Numberofcopies
syncvg VolumeGroupName

How do I remove a copy of a logical volume?

You can use the rmlvcopy command to remove copies of logical partitions of a logical volume. To reduce the number of copies of each logical partition belonging to logical volume testlv, enter:

rmlvcopy testlv 2

Each logical partition in the logical volume now has at most two physical partitions.

Queries about volume groups

To show volume groups in the system, type:

lsvg

To show all the characteristics of rootvg, type:

lsvg rootvg

To show disks used by rootvg, type:

lsvg -p rootvg

How to add a disk to a volume group?

Type the following:

extendvg   VolumeGroupName   hdisk0 hdisk1 ... hdiskn

How do I find out what the maximum supported logical track group (LTG) size of my hard disk?

You can use the lquerypv command with the -M flag. The output gives the LTG size in KB. For instance, the LTG size for hdisk0 in the following example is 256 KB.

/usr/sbin/lquerypv -M hdisk0
256

You can also run the lspv command on the hard disk and look at the value for MAX REQUEST.

What does syncvg command do?

The syncvg command is used to synchronize stale physical partitions. It accepts names of logical volumes, physical volumes, or volume groups as parameters.

For example, to synchronize the physical partitions located on physical volumes hdisk6 and hdisk7, use:

syncvg -p hdisk4 hdisk5

To synchronize all physical partitions from volume group testvg, use:

syncvg -v testvg

How do I replace a disk?

extendvg VolumeGroupName hdisk_new
migratepv hdisk_bad hdisk_new
reducevg -d VolumeGroupName hdisk_bad

How can I clone (make a copy of ) the rootvg?

You can run the alt_disk_copy command to copy the current rootvg to an alternate disk. The following example shows how to clone the rootvg to hdisk1.

alt_disk_copy -d  hdisk1

Network

How can I display or set values for network parameters?

The no command sets or displays current or next boot values for network tuning parameters.

How do I get the IP address of my machine?

Type one of the following:

ifconfig -a

host Fully_Qualified_Host_Name

For example, type host cyclop.austin.ibm.com.

How do I identify the network interfaces on my server?

Either of the following two commands will display the network interfaces:

lsdev -Cc if

ifconfig -a

To get information about one specific network interface, for example, tr0, run the command:

ifconfig tr0

How do I activate a network interface?

To activate the network interface tr0, run the command:

ifconfig tr0 up

How do I deactivate a network interface?

For example, to deactivate the network interface tr0, run the command:

ifconfig tr0 down

EFFICIENT COMMANDS

noreply@blogger.com (derrick caluag) — Thu, 13 Dec 2007 03:54:00 +0000

Bad: cat somefile | grep something
Better: grep something somefile
Why: You're running one program (grep) instead of two (cat and grep).

Bad: ps -ef | grep something | grep -v grep
Better: ps -ef | grep [s]omething
Why: You're running two commands (grep) instead of three (ps
and two greps).

Bad: cat /dev/null > somefile
Better: > somefile
Why: You're running a command (cat) with I/O redirection,
instead of just redirection.

Although the bad way will have the
same result, the good way is far
faster. This may seem trivial, but
the benefits will really show when
dealing with large files or loops.

Setting Up PureFTP server

noreply@blogger.com (derrick caluag) — Thu, 19 Jul 2007 07:48:00 +0000

Setting up Pure FTP server

1. download pureftpd website http://www.pureftpd.org/project/pure-ftpd/doc

http://download.pureftpd.org/pub/pure-ftpd/releases/pure-ftpd-1.0.21.tar.gz

2. compile i suggest you use "./configure --with-everything" to install all features

3. this ftp server have versatile auth methods (read the documention). but in my case i've use ftp authentiacation based on a independent password file.. below are the
steps.

a. create an "ftpgroup" group and an "ftpuser" user.

groupadd ftpgroup
useradd -g ftpgroup -d /dev/null -s /etc ftpuser

b. execute the following command to add the user

pure-pw useradd testaccount -u ftpuser -d /home/ftpusers/testaccount -N 200

where
user - testaccount
uid - ftpuser
chroot directory - /home/ftpusers/testaccount
disk quota - 200 MB

* this will create "/etc/pureftpd.passwd" by default

c. execute "pure-pw mkdb" to save the changes
* this will create "/etc/pureftpd.pdb"
* remember always execute this after changes made to password file

d. to check account info execute the following

pure-pw show testaccount

OUTPUT:

Login : testaccount
Password : $1$G5jGYrk0$n8vs/BsYv5a2cypCLMStm.
UID : 508 (ftpuser)
GID : 509 (ftpgroup)
Directory : /home/ftpusers/testaccount/./
Full name :
Download bandwidth : 0 Kb (unlimited)
Upload bandwidth : 0 Kb (unlimited)
Max files : 0 (unlimited)
Max size : 200 Mb (enabled)
Ratio : 0:0 (unlimited:unlimited)
Allowed local IPs :
Denied local IPs :
Allowed client IPs :
Denied client IPs :
Time restrictions : 0000-0000 (unlimited)
Max sim sessions : 0 (unlimited)

4. run pureftp server

/usr/local/sbin/pure-ftpd -j -lpuredb:/etc/pureftpd.pdb &

Documentation:

http://www.pureftpd.org/project/pure-ftpd/doc

LVM TUTORIAL BASICS

noreply@blogger.com (derrick caluag) — Sun, 06 May 2007 11:13:00 +0000

LVM TUTORIAL BASICS V 1.0 03/21/07

by derrick caluag

[root@intel-4 ~]# fdisk -l

Disk /dev/sda: 145.4 GB, 145492017152 bytes

255 heads, 63 sectors/track, 17688 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System

/dev/sda1 * 1 16 128488+ 83 Linux

/dev/sda2 17 1060 8385930 83 Linux

/dev/sda3 1061 1321 2096482+ 82 Linux swap

/dev/sda4 1322 17688 131467927+ 8e Linux LVM

INITIALIZATION

-- Create Physical Volume

pvcreate /dev/sda4

-- Create Volume Group

vgcreate VolG00 /dev/sda4

-- Create Logical Group (this will create 21G for LVhome)

lvcreate -L21000 VolG00 -n LVhome

-- Format the create Group with desired file system

mkfs.ext3 -b 4096 /dev/VolG00 / LVhome

-- Create Mount point on fstab

vi /etc/fstab

/dev/VolG00/LVhome /home ext3 defaults 1 2

-- Backup files on mountpoint

tar –zcvf /tmp/home.tgz /home

mv /home home2

mkdir home

-- Mount the partition

mount /dev/VolG00/LVhome

-- Untar the backup file back to the mount point

cd /home

cp /tmp/home.tgz

tar –zxvf home.tgz

EXTENDING LVM

-- Unmount partition

umount /dev/VolG00/LVhome

Extend LV

lvextend -L+1G /dev/VolG00/LVhome

add 1G to current size

lvextend -L12G /dev/VolG00/LVhome

extend size to 12G

-- Check extended LV for errors

e2fsck -f /dev/VolG00/LVhome

-- Resize the LV

resize2fs /dev/VolG00/LVhome

-- Remount the partition

mount /dev/VolG00/LVhome

Installing Perl Modules

noreply@blogger.com (derrick caluag) — Thu, 15 Mar 2007 04:50:00 +0000

This tutorial has been my guide now for quite a while... i hope you like it as much as i am.

CPAN

The Comprehensive Perl Archive Network (CPAN) holds many Perl modules and scripts, distributed among a large number of mirrors. The CPAN module provides an interface to query and install modules from CPAN. These notes document the setup and usage of CPAN, with attention to common tasks and pitfalls along the way.

Any Perl modules used by a site should be archived locally. Doing so ensures the modules can be installed on new systems, even if removed from CPAN.

Use CPAN::Reporter to submit module test results. Try SmokeAuto to automate module testing.

Alternatives

Other means of installing perl modules from CPAN include the following, which are not discussed in detail here.

CPANPLUS. “CPAN++ (also referred to and pronounced as CPANPLUS) is a new and flexible method of perl module management and installation using the CPAN. It aims to be a rewrite, and in time a replacement to the current CPAN module. In addition to fixing some long-standing problems, CPAN++ includes new features, such as module uninstall.”
PAR - Cross-Platform Packaging and Deployment tool.
Perl Package Manager (PPM) - Included with ActiveState Perl.
Other. Some vendors make perl modules available via other methods, such as ActiveState’s PPM, the FreeBSD ports system, or similar package software. These offer tight integration with the system in question, but may include outdated modules or use different naming conventions and filesystem layouts.

For example, p5-libwww is the FreeBSD port of the module distribution libwww-perl on CPAN, and LWP::UserAgent a module found in that distribution. The following commands are equivalent means to install libwww-perl via the FreeBSD ports system, yum on RedHat systems, or the cpan command included with modern versions of CPAN.

# portinstall p5-libwww
# yum -y install perl-libwww-perl
# cpan -i LWP::UserAgent

To lookup the documentation for a module, use http://search.cpan.org/perldoc/Module::Name. The documentation should also show the distribution a module belongs to, for example Data::Dumper. Other search interfaces include the CPAN Search Site or the CPAN shell search features.

Conversion scripts. cpan2rpm helps convert Perl modules into RedHat Package Manager (RPM) files. The resulting *.rpm packages can be installed via a local Yellowdog Updater, Modified (YUM) server. On Debian, try dh-make-perl --install --cpan Module::Name.

`perl` Upgrade Bug

The first time CPAN is invoked, it will run through a set of questions, such as which CPAN mirror site to use. Following the questions, CPAN may recommend that you install Bundle::CPAN or Bundle::libnet. Avoid installing these bundles!

Older versions of CPAN have a bug whereby a new version of perl itself may be installed. To avoid this bug, install the latest version of CPAN first. Setting the FTP_PASSIVE=1 environment variable avoids another common problem where active File Transfer Protocol (FTP) connections are blocked by a local firewall.

# perl -MCPAN -e '$ENV{FTP_PASSIVE} = 1; install CPAN'

If already in the CPAN shell following the preferences questions, use:

cpan> install CPAN

For reference, the bug is that Bundle::CPAN or Bundle::libnet may list Data::Dumper as a dependency. Data::Dumper is a built-in perl module, so when old versions of CPAN lookup Data::Dumper, they find a new version of perl to install. This bug has been fixed in current versions of CPAN.

Active FTP versus Firewalls

Network problems may prevent access to CPAN mirror sites. The chief problem will be utilities set to use active FTP, which most firewalls block. Persue Active FTP vs. Passive FTP, a Definitive Explanation for more details. I recommend enabling passive FTP by default, though this setting will need to be done for a variety of utilities CPAN might run, such as wget or Net::FTP. Alternatives include disabling the client firewall to allow active FTP connections back from the FTP server, or configuring a local FTP proxy.

Set the FTP_PASSIVE environment variable before running cpan.

# env FTP_PASSIVE=1 cpan -i Net::FTP

During the install of the libnet distribution, enable passive FTP.

…
Ah, I see you already have installed libnet before.

Do you want to modify/update your configuration (y|n) ? [no] y
…
Should all FTP connections be passive (y|n) ? [no] y

If Net::FTP is already installed, edit the libnet.cfg configuration file to use passive FTP.

$ perl -le 'for (@INC) { $_ .= "/".$ARGV[0]; print if -f }' Net/libnet.cfg
/usr/local/lib/perl5/5.8.1/Net/libnet.cfg
$ grep passive /usr/local/lib/perl5/5.8.1/Net/libnet.cfg
'ftp_int_passive' => 1,

If Net::FTP does not work, or certain utilities take too long to time out, consider the following options.

Disable Net::FTP.

If Net::FTP does not work, try adding the following line to the CPAN/Config.pm preferences file. More information on dontload_hash posted to the perl.perl5.porters newsgroup. Also consider installing LWP::UserAgent, which is more capable than Net::FTP.

'dontload_hash' => { 'Net::FTP' => 1 },

Disable utilities that do not work

To reconfigure CPAN to not call certain utilities, replace the path to the utility with a single space.

$ grep ncftp ~/.cpan/CPAN/MyConfig.pm
'ncftp' => q[ ],
'ncftpget' => q[ ],

Preferences Questions

CPAN will ask for preferences settings any time the Config.pm preferences file does not exist or is out of date. The default choice should be acceptable for most.

CPAN build and cache directory? [/root/.cpan]

I use /var/spool/cpan, as the root filesystem tends to be small on my systems, and the spool area makes more sense to me.

Policy on building prerequisites (follow, ask or ignore)? [ask]

Leave this setting set to ask when upgrading CPAN the first time, to prevent dependency lookups automatically installing the latest stable perl. With ask set, one can say no to queries that ask to install Bundle::CPAN, Bundle::libnet, or Data::Dumper until the latest version of CPAN is installed.

Where is your * program? [*]

This series of questions lets one configure (or disable) paths to various utilities CPAN may use to download or unpack modules. It is safe to leave entries blank, as long as CPAN is left with at least one working program that can download modules and another to expand them.

To disable a particular utility, use a single space instead of a file path.

Parameters for the 'make install' command?

Set this option to include UNINST=1 if installing as root. This properly cleans out files from older versions of a module being installed. For user-specific setup, I never set the UNINST option, to avoid remove warnings of unremovable system files.

Now we need to know where your favorite CPAN sites are located.

Choose several CPAN mirror sites. Use traceroute or bandwidth testing tools to determine which mirrors are best for your system. Or, mirror CPAN to a local system.

The mirrors list may need to be updated periodically, if a previous mirror site stops hosting CPAN. Symptoms of this will be slow downloads as CPAN fails though the mirror list.

Reconfiguring CPAN

To alter the CPAN preferences, either edit the Config.pm configuration file manually, or use the following command in the CPAN shell.

cpan> o conf init

The init configuration option runs through all the configuration questions, which may be time consuming. For example, other o conf commands can be used to list, remove, and add mirror sites, and then to save the changes to disk.

cpan> o conf urllist
urllist
ftp://ftp.kernel.org/pub/CPAN/
Type 'o conf' to view configuration edit options

cpan> o conf urllist shift

cpan> o conf urllist push ftp://ftp-mirror.internap.com/pub/CPAN/

cpan> o conf urllist
urllist
ftp://ftp-mirror.internap.com/pub/CPAN/
Type 'o conf' to view configuration edit options

cpan> o conf commit
commit: wrote /usr/local/lib/perl5/5.6.1/CPAN/Config.pm

To manually edit the existing configuration file, either open the user-specific ~/.cpan/CPAN/MyConfig.pm directly, or locate the system-wide configuration file (stored somewhere under the perl @INC path list) to edit with the following command.

$ perl -le 'for (@INC) { $_ .= $ARGV[0]; print if -f }' /CPAN/Config.pm
/System/Library/Perl/CPAN/Config.pm

Usage Tips

Once the latest version of CPAN has been properly installed, it is safe to install Bundle::CPAN to get the latest versions of modules CPAN depends on. If already in the CPAN shell, be sure to run reload cpan first.

cpan> reload cpan
…
cpan> install Bundle::CPAN

The following sections outline various uses and caveats with CPAN.

Invocation

The latest version of CPAN should install a cpan command somewhere on the system, which is easier to use than the traditional means of calling CPAN. With an up to date version of CPAN, the following sets of commands are equivalent. Hereafter, the shorter cpan method will be used.

# enter the CPAN shell
# perl -MCPAN -e shell
# cpan

# install the Acme::Bleach module
# perl -MCPAN -e install Acme::Bleach
# cpan -i Acme::Bleach

Depending on the shell in question, one may need to issue the hash -r or rehash command to make the new cpan command appear in the search path after the latest CPAN is installed. Consult your shell’s documentation for more information on whether this is required.

`autobundle`

The CPAN autobundle can be used to ease perl upgrades, by creating a special bundle containing all the installed modules of the current version of perl. This bundle can then be installed once the new version of perl is installed.

cpan> autobundle
…

Wrote bundle file
/var/spool/cpan/Bundle/Snapshot_2003_10_01_00.pm

cpan> quit

# upgrade perl here …

# cpan
cpan> install Bundle::Snapshot_2003_10_01_00

Autobundle appears to install the modules in alphabetical order; setting the prerequisites_policy policy to ask should help. Multiple install runs may be needed to install everything properly. Module build failures will lead to much recursion on the part of CPAN.

Debugging

Should tests fail during the make test phase of the module install process, the tests should be investigated to determine their impact. If the failed tests are not relevant to the system in question, the module can be installed with the force option. Otherwise, filing a bug report or otherwise contacting the module author may be in order.

Force Install

To force install a module, use the force option.

cpan> force install HTML::Mason

Verbose Testing

More verbose testing will need to be done from the command line. This can be done with the look command from the CPAN shell, along with subsequent shell code as shown in the following example for HTML::Mason, with verbose test logging saved to test.log via the tee(1) command.

cpan> install HTML::Mason
Running install for module HTML::Mason
Running make for D/DR/DROLSKY/HTML-Mason-1.23.tar.gz
…
t/02a-filter..........ok
t/04-misc.............FAILED tests 9-10
Failed 2/11 tests, 81.82% okay
t/05-request..........ok
…
Failed Test Stat Wstat Total Fail Failed List of Failed
---------------------------------------------------------------------------
t/04-misc.t 11 2 18.18% 9-10
2 tests skipped.
Failed 1/23 test scripts, 95.65% okay. 2/376 subtests failed, 99.47% okay.
*** Error code 35

Stop in /var/spool/cpan/build/HTML-Mason-1.23.
/usr/bin/make test -- NOT OK
Running make install
make test had returned bad status, won't install without force

cpan>
cpan> look HTML::Mason
Running look for module HTML::Mason

Trying to open a subshell in the build directory...
Working directory is /var/spool/cpan/build/HTML-Mason-1.23
# make test TEST_VERBOSE=1 TEST_FILE=t/04-misc.t | tee test.log
…

Determination as to whether the failed test is relevant to the system in question will need to be done by a human, typically by running of the test code and consulting the test script and module code to see what is failing. If the failed tests are for features of the module that will not be used, then the module typically can be installed and used without problems.

Old Modules

Some modules found by CPAN are out of date, and will not compile. An updated module may be available on CPAN, just not linked to as “current” by CPAN. Modules known to have this problem include the following. The links below should point to the current version of the modules.

Mac OS X

Problems with CPAN on Mac OS X.

Manual Build

On occasion one may need to manually build or test a module, or consult the module directory to read the documentation on any special needs the module may have. This can be done with the CPAN shell look command.

cpan> look Net::SSLeay
…
Working directory is /var/spool/cpan/build/Net_SSLeay.pm-1.25
# exit
cpan>

`sudo`

If CPAN is installed in your home directory, the system-wide cpan may cause problems when run via sudo(8), as by default sudo will invoke CPAN using the ~/.cpan/CPAN/MyConfig.pm configuration, but as root, which causes no end of trouble. To avoid this problem, reset the HOME environment variable with the -H option to sudo when invoking CPAN.

$ sudo -H cpan

Uninstalling

CPAN itself offers no uninstall method. Several of the alternatives to CPAN do, such as CPANPLUS or vendor package/port systems. If the module has been fully installed along with a .packlist file for the module, the ExtUtils::Packlist perl module documentation includes code for a modrm command to cleanly remove an installed module.

Modules built with other tools, such as Module::Build, may not write out a .packlist file for use by ExtUtils::Packlist.

Upgrading

How to upgrade all the modules on the system like apt-get is actually documented in the CPAN manual; however, the question comes up often enough that I answer it here as well.

# install everything that is outdated on my disk:
# perl -MCPAN -e 'CPAN::Shell->install(CPAN::Shell->r)'

Problems with this include new versions of modules that may break old module behavior, or various modules that cannot be upgraded due to build failures or system incompatibilities. Best to subject a test system to this sort of mass module upgrade before attempting it on a production system.

if you need to change server pls check this cool site below

CPAN SERVER SITES:

http://www.cpan.org/SITES.html

HOW TO SETUP DIAL-IN SERVER on LINUX

noreply@blogger.com (derrick caluag) — Wed, 11 Oct 2006 05:23:00 +0000

A lot of my friends have been asking me how to setup a dial-in server on a linux box.. As far as im an concern i was able to make this kind of setup on a debian os.. i've tried it on ubuntu on breezy and dappeldrake and it both went well.. only it requires you to have a modem preferably external or internal will also do and a dedicated line to be used by the dial-in users.. below are the steps that i followed:

Part I . The short version:D on how to get remote access to your Ubuntu box via modem. Install mgetty
sudo apt-get install mgetty
Add a line at the end of file /etc/inittab
S0:2345:respawn:/sbin/mgetty ttyS0
If your modem is on COM1.
Initialize init by typing
sudo init q
Now from Win you can use HyperTerminal to connect to your Ubuntu box with your user name/pass.

For those who want more here is a real deal;)

Part II

The problem: Establish PPP connection to Ubuntu server from a remote location using a modem and to share internet connection.
Laptop modem<> Server modem <> Ethernet Router <> Cable/DSL modem <> Internet

Assumptions: drivers for your modems already installed and modem is at ttyS0. I have an external modem attached to COM1 - ttyS0, COM2 will be ttyS1. I didn't have X installed so I was using nano to edit conf files, you can use gedit if you have X installed or any other editor. Make sure your are familiar with the interface of the editor before you start modifying files. Make sure you create backups of the files before you modify them. You will need to use sudo or login as root for most of the tasks. If you don't know how to configure your dial up on your client look for a dial up howto or Ubuntu docs. I also assume that you already have your local nework including routers properly configured and have an access to the Internet from your Ubuntu server.

Part II.a - Dial in configuration

1. If not already installed use synaptic or apt-get to install ppp and mgetty packages. ppp should be already installed by default so
sudo apt-get install mgetty

2. Create a group ppp by adding a line in file /etc/group ppp:x:1001:

3. Create a new user "pppuser" or whatever you will use for your dial in connection and assign a password by using
sudo adduser pppuser
edit file /etc/passwd or use sudo vipw to change entry for pppuser to pppuser:x:1001:1001:,,,:/home/pppuser:/usr/sbin/ppplogin

4. Add a line to the file /etc/inittab S0:2345:respawn:/sbin/mgetty ttyS0 for modem on ttyS0. Or S1:2345:respawn:/sbin/mgetty ttyS1 for modem on ttyS1 That will let mgetty to accept incoming calls

5.Make a new file /usr/sbin/ppplogin and add the following in there
#!/bin/sh
#/etc/ppp/ppplogin
# PPP login script
mesg n
stty -echo
exec /usr/sbin/pppd -detach modem debug crtscts

6. Set access to the ppplogin file and etc/ppp directory
chmod 750 /usr/sbin/ppplogin
chown root:ppp /usr/sbin/ppplogin
chmod 775 /etc/ppp
chown root:root -R /etc/ppp

7. Restart init by typing init q
If you're use external modem it should be on before that.

8. Open file /etc/mgetty/login.config Comment out everything in there and add a line
/AutoPPP/ - a_ppp /usr/sbin/pppd file /etc/ppp/options

9. Open file /etc/ppp/options and make sure these lines are uncommented. If anything else is uncommented it probably should be commented.

-detach
asyncmap 0
modem
crtscts
proxyarp
lock
require-pap
refuse-chap
ms-dns 192.168.1.1 #put your dns server ip here
usepeerdns
In my case the ms-dns entry had an ip of my router, if you using Linksys router it's 192.168.1.1 by default unless you changed it.

10. Create a file /etc/ppp/options.ttyS0 for the modem on ttyS0 and add following in there
192.168.1.3:192.168.1.201
noauth
Where first address is the address of your server for ppp connection which I think, should be different from your eth ip. The second address is the address that will be assigned to the client when connection is established. It will probably make life easier, unless you know what you doing, if all those addresses on the same subnet as your other computers on the network. (ip starts with the same 192.168.1.x numbers)
You can substitute noauth for a debug line, this way it will log some info about you connection in a syslog.

11. Edit file /etc/ppp/pap-secrets
find a line after # Every regular user can use PPP and has to use passwords from /etc/passwd
It should look something like that
* hostname "" *
substitute hostnatname with * so it looks like that
* * "" *

If you don't do that pap will not authenticate you and you'll be immediately disconnected.

Now you're able to connect using dial-up connection from you laptop or a remote office into your Ubuntu server and use ssh or putty if you're using Win.

Part II.b - Accessing internet from a remote client

I'm sure there other or better solutions to that, but that was easy enough and it worked for me.

sudo apt-get install ipmasq

Done. ipmasq automatically senses all your interfaces and initializes IP Masquerade forwarding/firewalling and allows you to connect to the rest of your network and the Internet.

SETTING TWO IP ADDRESS in ONE LAN card or NIC

noreply@blogger.com (derrick caluag) — Tue, 27 Jun 2006 04:46:00 +0000

SETTING TWO IP ADDRESS in ONE LAN card or NIC.

Two options either you add it at /etc/netword/interfaces or you set using ifconfig

1. TO set using IFCONFIG (temporary)

ifconfig eth1:1 netmask 255.255.255.0

2. TO add permanently

for debian flavors:

edit
/etc/network/interfaces

iface eth1:1 inet static
address
netmask
broadcast
gateway

Adding Additional Hard drive on your Linux Machine

noreply@blogger.com (derrick caluag) — Tue, 16 May 2006 16:35:00 +0000

Normally one would ask? how do i add additional harddrive to my linux box.. well we could make use of utilities like fdisk, cfdisk or QtParted but it is fdisk that is im going to discuss below.

Why FDISK.. the answer is simple. since fdisk is the utility that i've been using eversince i've tried linux. :)

Here are the steps:

You must first be able to identify which partion is your new harddrive either though dmesg or using fdisk utility

 # fdisk -l

The output will display the current harddrive informations and which device it is assigned to.
for scsi drive its normally /dev/sda while for IDE drive its /dev/hda

      # fdisk /dev/hdc

      Command (m for help): _

For a short manual we need to enter the 'm' command:

        Command (m for help): m
      Command action
         a   toggle a bootable flag
         b   edit bsd disklabel
         c   toggle the dos compatibility flag
         d   delete a partition
         l   list known partition types
         m   print this menu
         n   add a new partition
         o   create a new empty DOS partition table
         p   print the partition table
         q   quit without saving changes
         s   create a new empty Sun disklabel
         t   change a partition's system id
         u   change display/entry units
         v   verify the partition table
         w   write table to disk and exit
         x   extra functionality (experts only)

      Command (m for help):

We need to know just few necessary commands: d,p,n,q,w. Don't be afraid to use them--all your changes will be done only in memory and will only be written to the hard after the 'w' command is entered. If we have an error, we just need to cancel all changes with the command 'q'.

First of all, let's make ourself sure that disk is empty:

        Command (m for help): p

      Disk /dev/hdc: 64 heads, 63 sectors, 787 cylinders
      Units = cylinders of 4032 * 512 bytes

         Device Boot    Start       End    Blocks   Id  System

      Command (m for help):

Often sellers of PCs and hardware will pre-divide disks into partitions. In such cases we can use command 'd' (described below) to delete everything what we do not need.

So, let's create a new parititon (with command 'n'), answering all the questions as we go:

        Command (m for help): n
      Command action
         e   extended
         p   primary partition (1-4)

Choosing the partition type-- primary or extended--we will enter P for primary.

In choosing number of the partition in this example, we will assign all of the all free space to one partition. Because this will be the first and only existing partition, we will assign the number 1:

        Partition number (1-4): 1

When setting the number of the first cylinder of the partition, we can just use the default value, which is recorded when we just press Enter:

        First cylinder (1-787, default 1):
      Using default value 1

Setting the number of the last cylinder of the partition is easy in this example, since we are filling the entire drive with one partition. Again, just press Enter for the default (instead of the number of the cylinder, we can set size of partition in bytes, kbytes, or megabytes):

        Last cylinder or +size or +sizeM or +sizeK (1-787, default 787):
      Using default value 787

      Command (m for help):

Now, partition is created. We can take a look of new table of partitions with the help of the 'p' command:

        Command (m for help): p

      Disk /dev/hdc: 64 heads, 63 sectors, 787 cylinders
      Units = cylinders of 4032 * 512 bytes

         Device Boot    Start       End    Blocks   Id  System
      /dev/hdc1             1       787   1586560+  83  Linux

      Command (m for help):

If we don't like (for some reason) the location or number of the partition, we can delete it using 'd' command:

        Command (m for help): d
      Partition number (1-4): 1
      Command (m for help):

If you want to divide the disk into a few partitions, you will need to repeat all these operations a few times. One thing that is important to remember is that if the amount of partitions is greater than four, you'll need to create not primary, but an extended partition across the whole available disk space. Inside this partition you can create as many logical parts as needed.

Remember, please, that logical partitions always should be numbered from 5 upwards; it doesn't matter how many primary partitions were created before (one, three, or none at all).

After a partition has been made. you may want to format it using mkfs command. you could use mkfs.ext3 depending on what type of partiition that you desired.

mkfs.ext3 /dev/hdc1

After formating you may want to mount it to your linux box so that you could use it already

mount /dev/hdc1 /u01

or simply add it on your fstab so that you dont need to remount it everytime your system is restarted.

3-legged 'Transparent Proxy' firewall using IPFilter 4.1.8, Squid on Fedora Core 1

noreply@blogger.com (derrick caluag) — Mon, 01 May 2006 03:46:00 +0000

3-legged 'Transparent Proxy' firewall using IPFilter 4.1.8, Squid on Fedora Core 1
Date: Oct 8, 2005
by Jett Tayer <>

Download and install apt for Fedora Core 1
# cd /usr/local/src
# wget http://apt.sw.be/fedora/1/en/i386/dag/RPMS/apt-0.5.15cnc6-4.1.fc1.rf.i386.rpm
# wget http://apt.sw.be/fedora/1/en/i386/dag/RPMS/apt-devel-0.5.15cnc6-4.1.fc1.rf.i386.rpm
# rpm -ivh apt-0.5.15cnc6-4.1.fc1.rf.i386.rpm
# rpm -ivh apt-devel-0.5.15cnc6-4.1.fc1.rf.i386.rpm
Update your apt database
# apt-get update
Upgrade your packages
# apt-get upgrade
Upgrade the kernel
# apt-get install kernel#2.4.22-1.2199.nptl kernel-source#2.4.22-1.2199.nptl
Install some needed apps
# apt-get install patch rpm-build
Restart your machine and boot the newly installed kernel.
Download and extract the Squid package.
# apt-get install squid
Configure Squid to do 'transparent proxying'
# vi /etc/squid/squid.conf
You will need to make at least the following changes in /etc/squid/squid.conf
http_port 3128
http_access deny to_localhost
acl our_networks src 192.168.1.0/24 192.168.2.0/24
http_access allow our_networks
visible_hostname your.server.name.dom
httpd_accel_host virtual
httpd_accel_port 80
httpd_accel_with_proxy on
httpd_accel_uses_host_header on
Fire up Squid!
# service squid start
Install Bind 9: Provide caching DNS service to LAN only
# apt-get install bind bind-chroot
# service named start
Install IPFilter
Download and extract ipfilter software package
# wget http://coombs.anu.edu.au/~avalon/ip_fil4.1.8.tar.gz
# gzip -cd ip_fil4.1.8.tar.gz tar xvf -
# cd ip_fil4.1.8
Edit Makefile
# vi Makefile
look for the line,
LINUXKERNEL=/usr/src/linux
and change it to,
LINUXKERNEL=/usr/src/linux-2.4
Uncomment the following 3 lines
STATETOP_CFLAGS=-DSTATETOP
STATETOP_INC=
STATETOP_INC=-I/usr/local/include
and change the last line
STATETOP_INC=-I/usr/local/include
to
STATETOP_INC=-I/usr/include
Uncomment the following 2 lines
STATETOP_LIB=-lncurses
STATETOP_LIB=-L/usr/local/lib -lncurses
and change the last line
STATETOP_LIB=-L/usr/local/lib -lncurses
to
STATETOP_LIB=-L/usr/lib -lncurses
Next look for the line
POLICY=-DIPF_DEFAULT_PASS=FR_PASS
and change it to
POLICY=-DIPF_DEFAULT_PASS=FR_BLOCK
Save the file
# wq!
Compile IPFilter
# make linux
# make install-linux
Note:
There will be errors about ipfilter.o not being found.
Just copy ipfilter.o created in 'make-linux' command above in
/usr/src/redhat/BUILD/ipfilter/lib/modules/2.4.22-1.2199.nptl/kernel/net/ipv4/
then do a "make install-linux" again.
Still there will be errors, but don't worry because ipfilter RPM file will
be written in /usr/src/redhat/RPMS/i386. In that case just go directly
to the location of IPFilter RPM file and install it manually.
# cd /usr/src/redhat/RPMS/i386/
# rpm -ivh ipfilter-4.1.8-1.i386.rpm
IPFilter is now installed.
Config file (/etc/ipf.conf)
Here is my working ipf.conf for a 3-legged firewall
############################
### ipf.conf starts here ###
#
# $Linux ipf.conf 2005/07/17 16:15:55 tayer Exp $
#
# See /usr/share/ipfilter/examples for syntax and examples.
# eth0 is connected to the Internet with ip address 10.10.10.1 which is part of
# 10.10.10.0/24 network (not my real ip block of course!)
# eth1 is connected to the private subnet 192.168.1.0/24, 192.168.1.1 is the IP of eth1
# eth2 is connected to the private subnet 192.168.2.0/24, 192.168.2.1 is the IP of eth2
# Filtering:
block in all
block out all
block in quick on eth0 from 127.0.0.0/8 to any
block in quick on eth0 from 192.168.0.0/16 to any
block in quick on eth0 from 172.16.0.0/12 to any
block in quick on eth0 from 10.0.0.0/8 to any
block in quick on eth0 from 169.254.0.0/16 to any
block in quick on eth0 from 223.0.0.0/8 to any
block in quick on eth0 from 198.18.0.0/15 to any
block in quick on eth0 from 197.0.0.0/8 to any
block in quick on eth0 from 224.0.0.0/3 to any
block out quick on eth0 from any to 127.0.0.0/8
block out quick on eth0 from any to 192.168.0.0/16
block out quick on eth0 from any to 172.16.0.0/12
block out quick on eth0 from any to 10.0.0.0/8
block out quick on eth0 from any to 169.254.0.0/16
block out quick on eth0 from any to 223.0.0.0/8
block out quick on eth0 from any to 198.18.0.0/15
block out quick on eth0 from any to 197.0.0.0/8
block out quick on eth0 from any to 224.0.0.0/3
# What's these?? :)
block in log quick on eth0 from any to 10.10.10.0
block in log quick on eth0 from any to 10.10.10.255
block in log quick on eth0 from any to 255.255.255.255
##### Block a bunch of different nasty things. ############
# That I don"t want to see in the log
#
# Block frags
block in log quick on eth0 all with frags
# Block short tcp packets
block in log quick from any to any with ipopts
block in log quick all with short
# Block anything with special options
block in log quick all with ipopts
#
# Log packets with BOTH ssrr and lsrr set
log in all with opt lsrr,ssrr
# block source routed packets
block in log quick all with opt lsrr
block in log quick all with opt ssrr
# Block nmap OS fingerprint attempts
# Log first occurrence of these so I can get their IP address
block in log first quick on eth0 proto tcp from any to any flags FUP
# Block public pings
#block in log quick on eth0 proto icmp all
# Allow loopback packets freely
pass in quick on lo
pass out quick on lo
# Allow LAN packets freely
# allow freely packets from 192.168.1.0/24 LAN
pass in quick on eth1
pass out quick on eth1
# allow freely packets from 192.168.2.0/24 LAN
pass in quick on eth2
pass out quick on eth2
# Allow incoming data channel for outgoing connections, reject
# and log all incoming control connections
pass out quick on eth0 proto tcp from any to any port = 21 flags S keep state
# Allow SSH
pass in on eth0 proto tcp from any to eth0/32 port = 22 flags S/SA keep state
# Allow SMTP traffic
#pass in on eth0 proto tcp from any to eth0/32 port = 25 flags S/SA keep state
# Allow DNS traffic (tcp & axfr)
#pass in on eth0 proto tcp from any to eth0/32 port = 53 flags S/SA keep state
# Allow DNS traffic (udp)
#pass in on eth0 proto udp from any to eth0/32 port = 53 keep state
# Allow outside world to ping me (bad idea)
#pass in on eth0 proto icmp from any to any icmp-type 8 code 0 keep state keep frags
# Allow me to ping the outside world
pass out quick proto icmp from any to any icmp-type 8 code 0 keep state keep frags
# Allow all outgoing tcp traffic
pass out on eth0 proto tcp all flags S/SA keep state
# Allow all outgoing udp traffic
pass out on eth0 proto udp all keep state
#
### ipf.conf ends here ###
##########################
Config file (/etc/ipnat.conf)
Here is my working ipnat.conf for my 3-legged firewall
### ipnat.conf starts here ###
#
map eth0 192.168.1.0/24 -> 10.10.10.1/32 proxy port ftp ftp/tcp
map eth0 192.168.1.0/24 -> 10.10.10.1/32 portmap tcp/udp 40000:60000
map eth0 192.168.1.0/24 -> 10.10.10.1/32
map eth0 192.168.2.0/24 -> 10.10.10.1/32 proxy port ftp ftp/tcp
map eth0 192.168.2.0/24 -> 10.10.10.1/32 portmap tcp/udp 40000:60000
map eth0 192.168.2.0/24 -> 10.10.10.1/32
#
# Redirection is triggered for input packets.
# For example, to redirect FTP connections through this box, to the local ftp
# port, forcing them to connect through a proxy, you would use:
#
rdr eth0 0.0.0.0/0 port ftp -> 127.0.0.1 port ftp
#
# squid transparent proxy
rdr eth1 192.168.1.1/32 port 80 -> 192.168.1.1 port 80
rdr eth1 0.0.0.0/0 port 80 -> 192.168.1.1 port 3128
rdr eth1 192.168.2.1/32 port 80 -> 192.168.2.1 port 80
rdr eth1 0.0.0.0/0 port 80 -> 192.168.2.1 port 3128
#
### ipnat.conf ends here ###
Enable IP Forwarding:
Add this line in /etc/sysctl.conf if not already there
# echo "net.ipv4.ip_forward = 1" >> /etc/sysctl.conf
Re-read /etc/sysctl.conf
# sysctl -p
Fire up IPFilter
# service ipfilter start
IPFilter admin commands
Display a table of data detailing firewall performance,
including how many packets have been passed or blocked.
# ipfstat -hio
To flush and load ipfilter rules
# ipf -Fa -f /etc/ipf.conf
To flush and load ipnat rules
# ipnat -CF -f /etc/ipnat.conf

Basic Linux Commands

noreply@blogger.com (derrick caluag) — Thu, 27 Apr 2006 11:02:00 +0000

BASIC LINUX COMMANDS

alias    Create an alias
awk      Find and Replace text, database sort/validate/index
break    Exit from a loop
builtin  Run a shell builtin

cal      Display a calendar
case     Conditionally perform a command
cat      Display the contents of a file
cd       Change Directory
cfdisk   Partition table manipulator for Linux
chgrp    Change group ownership
chmod    Change access permissions
chown    Change file owner and group
chroot   Run a command with a different root directory
cksum    Print CRC checksum and byte counts
clear    Clear terminal screen
cmp      Compare two files
comm     Compare two sorted files line by line
command  Run a command - ignoring shell functions
continue Resume the next iteration of a loop
cp       Copy one or more files to another location
cron     Daemon to execute scheduled commands
crontab  Schedule a command to run at a later time
csplit   Split a file into context-determined pieces
cut      Divide a file into several parts

date     Display or change the date & time
dc       Desk Calculator
dd       Data Dump - Convert and copy a file
declare  Declare variables and give them attributes
df       Display free disk space
diff     Display the differences between two files
diff3    Show differences among three files
dir      Briefly list directory contents
dircolors Colour setup for `ls'
dirname  Convert a full pathname to just a path
dirs     Display list of remembered directories
du       Estimate file space usage

echo     Display message on screen
ed       A line-oriented text editor (edlin)
egrep    Search file(s) for lines that match an extended expression
eject    Eject CD-ROM
enable   Enable and disable builtin shell commands
env      Display, set, or remove environment variables
eval     Evaluate several commands/arguments
exec     Execute a command
exit     Exit the shell
expand   Convert tabs to spaces
export   Set an environment variable
expr     Evaluate expressions

factor   Print prime factors
false    Do nothing, unsuccessfully
fdformat Low-level format a floppy disk
fdisk    Partition table manipulator for Linux
fgrep    Search file(s) for lines that match a fixed string
find     Search for files that meet a desired criteria
fmt      Reformat paragraph text
fold     Wrap text to fit a specified width.
for      Expand words, and execute commands
format   Format disks or tapes
free     Display memory usage
fsck     Filesystem consistency check and repair.
function Define Function Macros

gawk     Find and Replace text within file(s)
getopts  Parse positional parameters
grep     Search file(s) for lines that match a given pattern
groups   Print group names a user is in
gzip     Compress or decompress named file(s)

hash     Remember the full pathname of a name argument
head     Output the first part of file(s)
history  Command History
hostname Print or set system name

id       Print user and group id's
if       Conditionally perform a command
import   Capture an X server screen and save the image to file
info     Help info
install  Copy files and set attributes

join     Join lines on a common field

kill     Stop a process from running

less     Display output one screen at a time
let      Perform arithmetic on shell variables
ln       Make links between files
local    Create variables
locate   Find files
logname  Print current login name
logout   Exit a login shell
lpc      Line printer control program
lpr      Off line print
lprint   Print a file
lprintd  Abort a print job
lprintq  List the print queue
lprm     Remove jobs from the print queue
ls       List information about file(s)

m4       Macro processor
man      Help manual
mkdir    Create new folder(s)
mkfifo   Make FIFOs (named pipes)
mknod    Make block or character special files
more     Display output one screen at a time
mount    Mount a file system
mtools   Manipulate MS-DOS files
mv       Move or rename files or directories

nice     Set the priority of a command or job
nl       Number lines and write files
nohup    Run a command immune to hangups

passwd   Modify a user password
paste    Merge lines of files
pathchk  Check file name portability
popd     Restore the previous value of the current directory
pr       Convert text files for printing
printcap Printer capability database
printenv Print environment variables
printf   Format and print data
ps       Process status
pushd    Save and then change the current directory
pwd      Print Working Directory

quota    Display disk usage and limits
quotacheck Scan a file system for disk usage
quotactl Set disk quotas

ram      ram disk device
rcp      Copy files between two machines.
read     read a line from standard input
readonly Mark variables/functions as readonly
remsync  Synchronize remote files via email
return   Exit a shell function
rm       Remove files
rmdir    Remove folder(s)
rpm      Remote Package Manager
rsync    Remote file copy (Synchronize file trees)

screen   Terminal window manager
sdiff    Merge two files interactively
sed      Stream Editor
select   Accept keyboard input
seq      Print numeric sequences
set      Manipulate shell variables and functions
shift    Shift positional parameters
shopt    Shell Options
shutdown Shutdown or restart linux
sleep    Delay for a specified time
sort     Sort text files
source   Run commands from a file `.'
split    Split a file into fixed-size pieces
su       Substitute user identity
sum      Print a checksum for a file
symlink  Make a new name for a file
sync     Synchronize data on disk with memory

tac      Concatenate and write files in reverse
tail     Output the last part of files
tar      Tape ARchiver
tee      Redirect output to multiple files
test     Evaluate a conditional expression
time     Measure Program Resource Use
times    User and system times
touch    Change file timestamps
top      List processes running on the system
traceroute Trace Route to Host
trap     Run a command when a signal is set(bourne)
tr       Translate, squeeze, and/or delete characters
true     Do nothing, successfully
tsort    Topological sort
tty      Print filename of terminal on stdin
type     Describe a command

ulimit   Limit user resources
umask    Users file creation mask
umount   Unmount a device
unalias  Remove an alias
uname    Print system information
unexpand Convert spaces to tabs
uniq     Uniquify files
units    Convert units from one scale to another
unset    Remove variable or function names
unshar   Unpack shell archive scripts
until    Execute commands (until error)
useradd  Create new user account
usermod  Modify user account
users    List users currently logged in
uuencode Encode a binary file
uudecode Decode a file created by uuencode

v        Verbosely list directory contents (`ls -l -b')
vdir     Verbosely list directory contents (`ls -l -b')

watch    Execute/display a program periodically
wc       Print byte, word, and line counts
whereis  Report all known instances of a command   
which    Locate a program file in the user's path.
while    Execute commands
who      Print all usernames currently logged in
whoami   Print the current user id and name (`id -un')

xargs    Execute utility, passing constructed argument list(s)
yes      Print a string until interrupted

Mirror Your Web Site With rsync

noreply@blogger.com (derrick caluag) — Mon, 24 Apr 2006 14:31:00 +0000

Mirror Your Web Site With rsync

Version 1.0
Author: Falko Timme
Last edited 04/20/2006

This tutorial shows how you can mirror your web site from your main web server to a backup server that can take over if the main server fails. We use the tool rsync for this, and we make it run through a cron job that checks every x minutes if there is something to update on the mirror. Thus your backup server should usually be up to date if it has to take over.

rsync updates only files that have changed, so you do not need to transfer 5 GB of data whenever you run rsync. It only mirrors new/changed files, and it can also delete files from the mirror that have been deleted on the main server. In addition to that it can preserve permissions and ownerships of mirrored files and directories; to preserve the ownerships, we need to run rsync as root which is what we do here. If permissions and/or ownerships change on the main server, rsync will also change them on the backup server.

In this tutorial we will tunnel rsync through SSH which is more secure; it also means you do not have to open another port in your firewall for rsync - it is enough if port 22 (SSH) is open. The problem is that SSH requires a password for logging in which is not good if you want to run rsync as a cron job. The need for a password requires human interaction which is not what we want.

But fortunately there is a solution: the use of public keys. We create a pair of keys (on our backup server mirror.example.com), one of which is saved in a file on the remote system (server1.example.com). Afterwards we will not be prompted for a password anymore when we run rsync. This also includes cron jobs which is exactly what we want.

As you might have guessed already from what I have written so far, the concept is that we initiate the mirroring of server1.example.com directly from mirror.example.com; server1.example.com does not have to do anything to get mirrored.

I will use the following setup here:

Main server: server1.example.com (server1) - IP address: 192.168.0.100
Mirror/backup server: mirror.example.com (mirror) - IP address: 192.168.0.175
The web site that is to be mirrored is in /var/www on server1.example.com.

rsync is for mirroring files and directories only; if you want to mirror your MySQL database, please take a look at these tutorials:

I want to say first that this is not the only way of setting up such a system. There are many ways of achieving this goal but this is the way I take. I do not issue any guarantee that this will work for you!

1 Install rsync

First we have to install rsync on both server1.example.com and mirror.example.com. For Debian systems, this looks like this:

server1/mirror:

(We do this as root!)

apt-get install rsync

On other Linux distributions you would use yum (Fedora/CentOS) or yast (SuSE) to install rsync.

2 Create An Unprivileged User On server1.example.com

Now we create an unprivileged user called someuser on server1.example.com that will be used by rsync on mirror.example.com to mirror the directory /var/www (of course, someuser must have read permissions on /var/www on server1.example.com).

server1:

(We do this as root!)

useradd -d /home/someuser -m -s /bin/bash someuser

This will create the user someuser with the home directory /home/someuser and the login shell /bin/bash (it is important that someuser has a valid login shell - something like /bin/false does not work!). Now give someuser a password:

passwd someuser

3 Test rsync

Next we test rsync on mirror.example.com. As root we do this:

mirror:

rsync -avz -e ssh someuser@server1.example.com:/var/www/ /var/www/

You should see something like this. Answer with yes:

The authenticity of host 'server1.example.com (192.168.0.100)' can't be established.
RSA key fingerprint is 32:e5:79:8e:5f:5a:25:a9:f1:0d:ef:be:5b:a6:a6:23.
Are you sure you want to continue connecting (yes/no)?

<-- yes

Then enter someuser's password, and you should see that server1.example.com's /var/www directory is mirrored to /var/www on mirror.example.com.

You can check that like this on both servers:

server1/mirror:

ls -la /var/www

You should see that all files and directories have been mirrored to mirror.example.com, and the files and directories should have the same permissions/ownerships as on server1.example.com.

4 Create The Keys On mirror.example.com

Now we create the private/public key pair on mirror.example.com:

mirror:

(We do this as root!)

mkdir /root/rsync
ssh-keygen -t dsa -b 2048 -f /root/rsync/mirror-rsync-key

You will see something like this:

Generating public/private dsa key pair.
Enter passphrase (empty for no passphrase): [press enter here]
Enter same passphrase again: [press enter here]
Your identification has been saved in /root/cron/mirror-rsync-key.
Your public key has been saved in /root/cron/mirror-rsync-key.pub.
The key fingerprint is:
68:95:35:44:91:f1:45:a4:af:3f:69:2a:ea:c5:4e:d7 root@mirror

It is important that you do not enter a passphrase otherwise the mirroring will not work without human interaction so simply hit enter!

Next, we copy our public key to server1.example.com:

mirror:

(Still, we do this as root.)

scp /root/rsync/mirror-rsync-key.pub someuser@server1.example.com:/home/someuser/

The public key mirror-rsync-key.pub should now be available in /home/someuser on server1.example.com.

Mirror Your Web Site With rsync

noreply@blogger.com (derrick caluag) — Mon, 24 Apr 2006 14:31:00 +0000

Mirror Your Web Site With rsync

Version 1.0
Author: Falko Timme
Last edited 04/20/2006

I will use the following setup here:

Main server: server1.example.com (server1) - IP address: 192.168.0.100
Mirror/backup server: mirror.example.com (mirror) - IP address: 192.168.0.175
The web site that is to be mirrored is in /var/www on server1.example.com.

rsync is for mirroring files and directories only; if you want to mirror your MySQL database, please take a look at these tutorials:

1 Install rsync

First we have to install rsync on both server1.example.com and mirror.example.com. For Debian systems, this looks like this:

server1/mirror:

(We do this as root!)

apt-get install rsync

On other Linux distributions you would use yum (Fedora/CentOS) or yast (SuSE) to install rsync.

2 Create An Unprivileged User On server1.example.com

server1:

(We do this as root!)

useradd -d /home/someuser -m -s /bin/bash someuser

passwd someuser

3 Test rsync

Next we test rsync on mirror.example.com. As root we do this:

mirror:

rsync -avz -e ssh someuser@server1.example.com:/var/www/ /var/www/

You should see something like this. Answer with yes:

The authenticity of host 'server1.example.com (192.168.0.100)' can't be established.
RSA key fingerprint is 32:e5:79:8e:5f:5a:25:a9:f1:0d:ef:be:5b:a6:a6:23.
Are you sure you want to continue connecting (yes/no)?

<-- yes

Then enter someuser's password, and you should see that server1.example.com's /var/www directory is mirrored to /var/www on mirror.example.com.

You can check that like this on both servers:

server1/mirror:

ls -la /var/www

You should see that all files and directories have been mirrored to mirror.example.com, and the files and directories should have the same permissions/ownerships as on server1.example.com.

4 Create The Keys On mirror.example.com

Now we create the private/public key pair on mirror.example.com:

mirror:

(We do this as root!)

mkdir /root/rsync
ssh-keygen -t dsa -b 2048 -f /root/rsync/mirror-rsync-key

You will see something like this:

Generating public/private dsa key pair.
Enter passphrase (empty for no passphrase): [press enter here]
Enter same passphrase again: [press enter here]
Your identification has been saved in /root/cron/mirror-rsync-key.
Your public key has been saved in /root/cron/mirror-rsync-key.pub.
The key fingerprint is:
68:95:35:44:91:f1:45:a4:af:3f:69:2a:ea:c5:4e:d7 root@mirror

It is important that you do not enter a passphrase otherwise the mirroring will not work without human interaction so simply hit enter!

Next, we copy our public key to server1.example.com:

mirror:

(Still, we do this as root.)

scp /root/rsync/mirror-rsync-key.pub someuser@server1.example.com:/home/someuser/

The public key mirror-rsync-key.pub should now be available in /home/someuser on server1.example.com.

How To Set Up Database Replication In MySQL

noreply@blogger.com (derrick caluag) — Sun, 23 Apr 2006 08:07:00 +0000

How To Set Up Database Replication In MySQL

Version 1.1
Author: Falko Timme
Last edited: 01/14/2006

This tutorial describes how to set up database replication in MySQL. MySQL replication allows you to have an exact copy of a database from a master server on another server (slave), and all updates to the database on the master server are immediately replicated to the database on the slave server so that both databases are in sync. This is not a backup policy because an accidentally issued DELETE command will also be carried out on the slave; but replication can help protect against hardware failures though.

In this tutorial I will show how to replicate the database exampledb from the master with the IP address 192.168.0.100 to a slave. Both systems (master and slave) are running Debian Sarge; however, the configuration should apply to almost all distributions with little or no modification.

Both systems have MySQL installed, and the database exampledb with tables and data is already existing on the master, but not on the slave.

1 Configure The Master

First we have to edit /etc/mysql/my.cnf. We have to enable networking for MySQL, and MySQL should listen on all IP addresses, therefore we comment out these lines (if existant):

#skip-networking
#bind-address            = 127.0.0.1

Furthermore we have to tell MySQL for which database it should write logs (these logs are used by the slave to see what has changed on the master), which log file it should use, and we have to specify that this MySQL server is the master. We want to replicate the database exampledb, so we put the following lines into /etc/mysql/my.cnf:

log-bin = /var/log/mysql/mysql-bin.log
binlog-do-db=exampledb
server-id=1

Then we restart MySQL:

/etc/init.d/mysql restart

Then we log into the MySQL database as root and create a user with replication privileges:

mysql -u root -p
Enter password:

Now we are on the MySQL shell.

For mysql version 3.23 and below

GRANT LINE ON *.* TO 'slave_user'@'Host IP' IDENTIFIED BY ''; (Replace with a real password! and Host IP with ip adress or host.domainname will do)

For Mysql version 4 and up

GRANT REPLICATION SLAVE ON *.* TO 'slave_user'@'%' IDENTIFIED BY ''; (Replace with a real password!)
FLUSH PRIVILEGES;

* you could also use grant all privileges although not recommended

Next (still on the MySQL shell) do this:

USE exampledb;
FLUSH TABLES WITH READ LOCK;
SHOW MASTER STATUS;

The last command will show something like this:

+---------------+----------+--------------+------------------+
| File          | Position | Binlog_do_db | Binlog_ignore_db |
+---------------+----------+--------------+------------------+
| mysql-bin.006 | 183      | exampledb    |                  |
+---------------+----------+--------------+------------------+
1 row in set (0.00 sec)

Write down this information, we will need it later on the slave!

Then leave the MySQL shell:

quit;

There are two possibilities to get the existing tables and data from exampledb from the master to the slave. The first one is to make a database dump, the second one is to use the LOAD DATA FROM MASTER; command on the slave. The latter has the disadvantage the the database on the master will be locked during this operation, so if you have a large database on a high-traffic production system, this is not what you want, and I recommend to follow the first method in this case. However, the latter method is very fast, so I will describe both here.

If you want to follow the first method, then do this:

mysqldump -u root -p --opt exampledb > exampledb.sql (Replace with the real password for the MySQL user root! Important: There is no space between -p and !)

This will create an SQL dump of exampledb in the file exampledb.sql. Transfer this file to your slave server!

If you want to go the LOAD DATA FROM MASTER; way then there is nothing you must do right now.

Finally we have to unlock the tables in exampledb:

mysql -u root -p
Enter password:
UNLOCK TABLES;
quit;

Now the configuration on the master is finished. On to the slave...

2 Configure The Slave

On the slave we first have to create the database exampledb:

mysql -u root -p
Enter password:
CREATE DATABASE exampledb;
quit;

If you have made an SQL dump of exampledb on the master and have transferred it to the slave, then it is time now to import the SQL dump into our newly created exampledb on the slave:

mysql -u root -p exampledb < /path/to/exampledb.sql (Replace with the real password for the MySQL user root! Important: There is no space between -p and !)

If you want to go the LOAD DATA FROM MASTER; way then there is nothing you must do right now.

Now we have to tell MySQL on the slave that it is the slave, that the master is 192.168.0.100, and that the master database to watch is exampledb. Therefore we add the following lines to /etc/mysql/my.cnf:

server-id=2
master-host=192.168.0.100
master-user=slave_user
master-password=secret
master-connect-retry=60
replicate-do-db=exampledb

Then we restart MySQL:

/etc/init.d/mysql restart

If you have not imported the master exampledb with the help of an SQL dump, but want to go the LOAD DATA FROM MASTER; way, then it is time for you now to get the data from the master exampledb:

mysql -u root -p
Enter password:
LOAD DATA FROM MASTER;
quit;

If you have phpMyAdmin installed on the slave you can now check if all tables/data from the master exampledb is also available on the slave exampledb.

Finally, we must do this:

mysql -u root -p
Enter password:
SLAVE STOP;

In the next command (still on the MySQL shell) you have to replace the values appropriately:

CHANGE MASTER TO MASTER_HOST='192.168.0.100', MASTER_USER='slave_user', MASTER_PASSWORD='', MASTER_LOG_FILE='mysql-bin.006', MASTER_LOG_POS=183;

MASTER_HOST is the IP address or hostname of the master (in this example it is 192.168.0.100).
MASTER_USER is the user we granted replication privileges on the master.
MASTER_PASSWORD is the password of MASTER_USER on the master.
MASTER_LOG_FILE is the file MySQL gave back when you ran SHOW MASTER STATUS; on the master.
MASTER_LOG_POS is the position MySQL gave back when you ran SHOW MASTER STATUS; on the master.

Now all that is left to do is start the slave. Still on the MySQL shell we run

START SLAVE;
quit;

That's it! Now whenever exampledb is updated on the master, all changes will be replicated to exampledb on the slave. Test it!

How do I scan my Linux system for rootkits, worms, trojans, etc.?

noreply@blogger.com (derrick caluag) — Sat, 22 Apr 2006 17:47:00 +0000

Either with ckrootkit or with rkhunter.

chkrootkit:

Either install the package that comes with your distribution (on Debian you would run

apt-get install chkrootkit

), or download the sources from www.chkrootkit.org and install manually:

wget --passive-ftp ftp://ftp.pangeia.com.br/pub/seg/pac/chkrootkit.tar.gz

tar xvfz chkrootkit.tar.gz

cd chkrootkit-/

make sense

Afterwards, you can move the chkrootkit directory somewhere else, e.g. /usr/local/chkrootkit:

cd ..

mv chkrootkit-/ /usr/local/chkrootkit

Now you can run chkrootkit manually:

cd /usr/local/chkrootkit

./chkrootkit

(if you installed a chkrootkit package coming with your distribution, your chkrootkit might be somewhere else).

You can even run chkrootkit by a cron job and get the results emailed to you:

Run

crontab -e

to create a cron job like this:

0 3 * * * (cd /usr/local/chkrootkit-; ./chkrootkit 2>&1 | mail -s "chkrootkit output my server" you@yourdomain.com)

That would run chkrootkit every night a 3.00h.

rkhunter:

Download the latest rkhunter sources from www.rootkit.nl:

wget http://downloads.rootkit.nl/rkhunter-1.2.7.tar.gz

tar xvfz rkhunter-1.2.7.tar.gz

cd rkhunter/

./installer.sh

This will install rkhunter to the directory /usr/local/rkhunter. Now run

rkhunter --update

to download the latest chkrootkit/trojan/worm signatures (you should do this regularly).

Now you can scan your system for malware by running

rkhunter -c

TRACKING OF LOGINS AND LOGOUTS on LINUX / UNIX Distros

noreply@blogger.com (derrick caluag) — Tue, 18 Apr 2006 05:28:00 +0000

TRACKING OF LOGINS AND LOGOUTS

In the .login file add the commands:
------------------------------

------

echo login time `date` >> .daylogs/masterlog

grep -i "sun" .daylogs/masterlog > .daylogs/sunday.log
grep -i "mon" .daylogs/masterlog > .daylogs/monday.log
grep -i "tue" .daylogs/masterlog > .daylogs/tuesday.log
grep -i "wen" .daylogs/masterlog > .daylogs/wensday.log
grep -i "thu" .daylogs/masterlog > .daylogs/thursday.log
grep -i "fri" .daylogs/masterlog > .daylogs/friday.log
grep -i "sat" .daylogs/masterlog > .daylogs/saturday.log

In the .logout file add this line
-----------------------------------

echo logout time `date`>> .daylogs/masterlog

This script assumes you have a hidden
directory called .daylogs this helps keep it
out of sight and away from prying eyes and
if you keep root ownership of the directory
change the mode to:

chmod 744 .daylogs

This will not allow anyone to get in to the
directory to look around.

CREATING TRASH

noreply@blogger.com (derrick caluag) — Sat, 15 Apr 2006 04:02:00 +0000

CREATING TRASH

Sometimes unwittingly we may delete
some important files and realise it
later. To avoid such a situation,
you can use this following idea.

Create a small bash script containing
the line

mv $1 ~/trash/

Save this file in your home say
".srm" (safe rm) and in your
".bashrc" enter this line:

alias rm='~/.srm'

Now whenever you delete any files
it will go to "trash" directory
instead of deletion. You will
have to create a "trash" directory
in your home directory.

BASH SHELL OPTION

noreply@blogger.com (derrick caluag) — Thu, 13 Apr 2006 09:54:00 +0000

BASH SHELL OPTION

If you are using bash shell. There is
a way to cd a particular directory
even if you spelled incorrectly on the
command line. Set the shell option to:

shopt -s cdspell

eg:-
Suppose you want to cd to "cd /tmp"
and you have miss typed to "cd /pmp"
still it will cd to "cd /tmp".

This setting will be very usefull if
you have a long named directory.

NFS BETWEEN SOLARIS & LINUX

noreply@blogger.com (derrick caluag) — Tue, 11 Apr 2006 21:07:00 +0000

NFS BETWEEN SOLARIS & LINUX

If you receive error messages such
as "unknown version" when attempting to
mount a Linux based NFS server from
Solaris, you probably have an
incompatibility between the NFS versions
running on both of them. Linux uses
version 2, while Solaris uses version 3.
In order to get the machines to
communicate, you have to use the vers
option on the Solaris machine as follows:

mount -o vers=2 nfsserver:/remotedir /localdir

MAINTAINING LOG AND TMP FILE

noreply@blogger.com (derrick caluag) — Mon, 10 Apr 2006 18:10:00 +0000

MAINTAINING LOG AND TMP FILE

If you need to maintain an
application that generate
a lot of logfiles or tmp
files with running numbers
as part of the filename and
uses a common extension.
These two command together
will help to maintain it
for a window of time.

It compress those files that
are more than 24hrs and
have it remove after 120hrs.
You need to put it in
daily cron.

find $LOGDIR -name '*.ext' -mtime +0 -exec compress {} \;
find $LOGDIR -name '*.Z' -mtime +5 -exec rm -f {} \;

You can change the time to
suit your needs and use
wherever compressing utility
you have to save space.
If you need to maintain
directories created by
application here are help;

find $LOGDIR -type d -mtime +0 -exec compress -r {} \;
find $LOGDIR -type d -mtime +5 -exec rm -f {}
The compression is to save
space while waiting to be
deleted. Application
developers may need to read
these files/directories so
keep those files/directories
for a certain amount of time
before deleting.

EXTRACT CORRUPTED TAR FILE

noreply@blogger.com (derrick caluag) — Mon, 10 Apr 2006 18:08:00 +0000

EXTRACT CORRUPTED TAR FILE

In many case if there is a corrupted tar file,
the following command can be used in an attempt
to extract the file:

% cat [tar-filename] | tar -xvf -

NOTE: Where "-" is the STDOUT

EFFICIENT COMMANDS

noreply@blogger.com (derrick caluag) — Sun, 02 Apr 2006 06:16:00 +0000

EFFICIENT COMMANDS

I cringe anytime I see someone code
inefficiently. Here are three of the
most common mistakes, followed by a
better way to do the same thing.

Bad: cat somefile | grep something
Better: grep something somefile
Why: You're running one program (grep) instead of two (cat and grep).

Bad: ps -ef | grep something | grep -v grep
Better: ps -ef | grep [s]omething
Why: You're running two commands (grep) instead of three (ps
and two greps).

Bad: cat /dev/null > somefile
Better: > somefile
Why: You're running a command (cat) with I/O redirection,
instead of just redirection.

Although the bad way will have the
same result, the good way is far
faster. This may seem trivial, but
the benefits will really show when
dealing with large files or loops.

Removing Blank Line using SED

noreply@blogger.com (derrick caluag) — Sat, 01 Apr 2006 15:30:00 +0000

I SED BLANK

Using sed, you can remove blank lines, and
lines that contain only whitespace, from a
file using the following:

sed -e '/^[ ]*$/d' InputFile >OutputFile

Within the single quotes ('), the forward
slashes (/) delimit the regular expression
that will be interpreted by sed. The "d"
before the closing single quote, tells sed
to delete any lines that match the regular
expression.

Within the regular expression, the caret
(^) matches the beginning of a line.
The []* matches zero to many occurrences of
the character list between the open bracket
([) and the close bracket (]) (in the above
regular expression, you must insert a space
and a tab between the brackets). The dollar
sign ($) matches the end of a line.

These three constructs together match any
blank line or any line that contains only
spaces and tabs (in any combination).

Since the standard operation of sed is to
echo lines to stdout, all lines except blank
lines (or lines that only contain whitespace)
will be sent to OutputFile.

VI COPY FILE TO FILE

noreply@blogger.com (derrick caluag) — Thu, 30 Mar 2006 06:43:00 +0000

VI COPY FILE TO FILE

Here is how to copy the required number
of lines from one file to another in
VI editor. First use the following
key combinations in the source file.

Press ESCAPE
Press Shift "(Shift double quotes)
Press a
Press the number of lines you want to copy
press y followed by another y

Now press " : " (COLON) to get the vi prompt.
Hit e "Destination file name"
Once you enter the Destination file
go to the line where you want the lines
copied to be inserted.

Press ESCAPE.
Press SHIFT "(Double quotes).
Press a.
Press p.

The lines get copied.

FIND THOSE HIDDEN FILES

noreply@blogger.com (derrick caluag) — Thu, 30 Mar 2006 06:40:00 +0000

FIND THOSE HIDDEN FILES

Finding only hidden files
(starting with .) in a directory.

ls -a | grep "^\." OR
ls -a | awk '$0~/^\./ {print $0}'