How To Set Auto Login - CentOS

I did this on CentOS 6.3

For GUI auto login:

--> Edit  /etc/gdm/custom.conf with the following items
[daemon]
AutomaticLoginEnable=true
AutomaticLogin=username

# reboot

For CLI auto login:

Step 1)

Edit /etc/init/tty.conf, replace "exec /sbin/mingetty $TTY" with "exec /sbin/mingetty --autologin=root $TTY" (no quotes).


With step 1 above we are already get auto login for root but system will randomly assign tty for root. To assign fix tty number, do step 2 below.

Step 2)

Add "aa:3:respawn:/sbin/mingetty --noclear --autologin root tty1" into /etc/inittab.

This will fix root autologin on tty1.
aa is just a label.


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How to View Remote Console Message

A little tips if you want to view remote console message. It helps and saves my time in my works. This is needed when your server running in run level 3 and has application running.

/dev/vcs1 -> console device file

To view virtual console message, remote login to server and run command below:

# cat /dev/vcs1
10:23:14 server2 1 some message here
10:23:44 server2 1 some message here
10:24:14 server2 1 some message here

I use putty with default window size to give best output.

Next, we can make it easy for us with a script like example below:

#! /bin/sh
cat /dev/vcs1 >> output1
sleep 30
exec /tmp/script1

This script will create a file called output1 and save remote console message.

Search keyword

This is brief on how to search certain keyword in files.

# grep -r "keyword" /path

example:
# grep -r "/etc/dovecot-sql.conf" /etc
/etc/dovecot/tem:        args = /etc/dovecot-sql.conf
/etc/dovecot/dovecot.conf:        args = /etc/dovecot-sql.conf

vi Editor Command Summary

i = insert

yy = copy current line
p = paste

:44 = go to line 44

VirtualBox with Broadband Access

I have VirtualBox installed on

Host: Windows XP
Guest: CentOS 6.3.

I tried to make my Guest OS to work with Internet via broadband.
Finally I got it worked. See image below for graphical settings. Enjoy!

Install LibreOffice 4.0 on CentOS 6.3

Installation file ---> LibreOffice_4.0.3_Linux_x86_rpm.tar.gz

# tar xzf LibreOffice_4.0.3_Linux_x86_rpm.tar.gz
# ll
-rw-rw-r-- 1 aatkt aatkt   6923631 May 11 07:33 install_flash_player_11_linux.i386.tar.gz
drwxr-xr-x 4 root  root       4096 May  2 20:35 LibreOffice_4.0.3.3_Linux_x86_rpm
-rw-rw-r-- 1 aatkt aatkt 184488945 Jun  4 11:06 LibreOffice_4.0.3_Linux_x86_rpm.tar.gz
# cd LibreOffice_4.0.3.3_Linux_x86_rpm/
# ls -l
  drwxr-xr-x 2 root root 4096 May  2 20:35 readmes
  drwxrwxr-x 3 root root 4096 May  2 20:35 RPMS
# cd RPMS/
# ls
desktop-integration
libobasis4.0-images-4.0.3.3-3.i586.rpm
...
...
...   

# rpm -ivh *.rpm
Preparing...                ########################################### [100%]
   1:libreoffice4.0-ure     ########################################### [  2%]
   2:libobasis4.0-core01    ########################################### [  4%]
   3:libobasis4.0-core02    ########################################### [  6%]
   4:libobasis4.0-core03    ########################################### [  8%]
   5:libobasis4.0-core04    ########################################### [ 10%]
   6:libobasis4.0-core05    ########################################### [ 12%]
   7:libobasis4.0-core06    ########################################### [ 14%]
   8:libobasis4.0-core07    ########################################### [ 16%]
   9:libobasis4.0-en-US     ########################################### [ 18%]
  10:libobasis4.0-base      ########################################### [ 20%]
  11:libobasis4.0-impress   ########################################### [ 22%]
  12:libobasis4.0-writer    ########################################### [ 24%]
  13:libobasis4.0-en-US-base########################################### [ 25%]
  14:libobasis4.0-en-US-calc########################################### [ 27%]
  15:libobasis4.0-en-US-math########################################### [ 29%]
  16:libobasis4.0-en-US-res ########################################### [ 31%]
  17:libobasis4.0-en-US-writ########################################### [ 33%]
  18:libobasis4.0-calc      ########################################### [ 35%]
  19:libobasis4.0-draw      ########################################### [ 37%]
  20:libobasis4.0-images    ########################################### [ 39%]
  21:libreoffice4.0         ########################################### [ 41%]
  22:libobasis4.0-math      ########################################### [ 43%]
  23:libreoffice4.0-math    ########################################### [ 45%]
  24:libreoffice4.0-base    ########################################### [ 47%]
  25:libreoffice4.0-calc    ########################################### [ 49%]
  26:libreoffice4.0-dict-en ########################################### [ 51%]
  27:libreoffice4.0-dict-es ########################################### [ 53%]
  28:libreoffice4.0-dict-fr ########################################### [ 55%]
  29:libreoffice4.0-draw    ########################################### [ 57%]
  30:libreoffice4.0-en-US   ########################################### [ 59%]
  31:libreoffice4.0-impress ########################################### [ 61%]
  32:libreoffice4.0-writer  ########################################### [ 63%]
  33:libobasis4.0-librelogo ########################################### [ 65%]
  34:libobasis4.0-ogltrans  ########################################### [ 67%]
  35:libobasis4.0-postgresql########################################### [ 69%]
  36:libobasis4.0-extension-########################################### [ 71%]
  37:libobasis4.0-extension-########################################### [ 73%]
  38:libobasis4.0-extension-########################################### [ 75%]
  39:libobasis4.0-extension-########################################### [ 76%]
  40:libobasis4.0-extension-########################################### [ 78%]
  41:libobasis4.0-extension-########################################### [ 80%]
  42:libobasis4.0-extension-########################################### [ 82%]
  43:libobasis4.0-gnome-inte########################################### [ 84%]
  44:libobasis4.0-graphicfil########################################### [ 86%]
  45:libobasis4.0-javafilter########################################### [ 88%]
  46:libobasis4.0-kde-integr########################################### [ 90%]
  47:libobasis4.0-onlineupda########################################### [ 92%]
  48:libobasis4.0-ooofonts  ########################################### [ 94%]
  49:libobasis4.0-ooolinguis########################################### [ 96%]
  50:libobasis4.0-pyuno     ########################################### [ 98%]
  51:libobasis4.0-xsltfilter########################################### [100%]

# cd desktop-integration# ll
total 19256
-rw-rw-r-- 1 root root 6529856 May  2 18:18 libreoffice4.0-freedesktop-menus-4.0.3-3.noarch.rpm
-rw-rw-r-- 1 root root 6566595 May  2 18:18 libreoffice4.0-mandriva-menus-4.0.3-3.noarch.rpm
-rw-rw-r-- 1 root root 6613278 May  2 18:20 libreoffice4.0-suse-menus-4.0.3-3.noarch.rpm
# rpm -ivh  libreoffice4.0-freedesktop-menus-4.0.3-3.noarch.rpm
Complete!

EXT3-fs error (device cciss/c0d0p5) in start_transaction: Journal has aborted

Today, I am trying to scp file from Linux server A to server B but got the following error.

[root@server-A local]# scp don.tar.gz server-B:/tmp 
root@server-B's password:
scp: /tmp/don.tar.gz: Read-only file system

Read-only file system error appeared. I waste a lot of time thinking the file permission that can caused the problem.

From dmesg, I got the following error:

[root@server-B ~]# dmesg
l has aborted
EXT3-fs error (device cciss/c0d0p5) in start_transaction: Journal has aborted
EXT3-fs error (device cciss/c0d0p5) in start_transaction: Journal has aborted
EXT3-fs error (device cciss/c0d0p5) in start_transaction: Journal has aborted
EXT3-fs error (device cciss/c0d0p5) in start_transaction: Journal has aborted
EXT3-fs error (device cciss/c0d0p5) in start_transaction: Journal has aborted
EXT3-fs error (device cciss/c0d0p5) in start_transaction: Journal has aborted
EXT3-fs error (device cciss/c0d0p5) in start_transaction: Journal has aborted
EXT3-fs error (device cciss/c0d0p5) in start_transaction: Journal has aborted
EXT3-fs error (device cciss/c0d0p5) in start_transaction: Journal has aborted
EXT3-fs error (device cciss/c0d0p5) in start_transaction: Journal has aborted

[root@server-B ~]# mount
/dev/cciss/c0d0p2 on / type ext3 (rw)
none on /proc type proc (rw)
none on /sys type sysfs (rw)
none on /dev/pts type devpts (rw,gid=5,mode=620)
usbfs on /proc/bus/usb type usbfs (rw)
/dev/cciss/c0d0p1 on /boot type ext3 (rw)
none on /dev/shm type tmpfs (rw)
/dev/cciss/c0d0p5 on /usr2 type ext3 (rw) <-- /usr2 
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)

Upon googling, I found useful information at http://major.io/2007/11/20/ext3-fs-error-device-hda3-in-start_transaction-journal-has-aborted/

In my case, the problem was resolved by reboot server-B and forced switch off. The system itself will recover the blocks and boot up, if not you can follow guide from link above. 

[root@server-A local]# scp don.tar.gz server-B:/tmp
root@server-B's password:
don.tar.gz                          100%   16MB 714.6KB/s   00:23


[root@server-B tmp]# df /tmp
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/cciss/c0d0p2     15480832   2697412  11997040  19% /

Even though "EXT3-fs error (device cciss/c0d0p5)" refer to /usr2 partition but it prevent me to scp to /tmp directory (which mounted on / partition).

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How to Update Adobe Flash Player for Firefox Internet Browser

Download the update. Let say we have install_flash_player_11_linux.i386.tar.gz

Extract the file
# tar xzf install_flash_player_11_linux.i386.tar.gz

The following files will be generated:
- libflashplayer.so
- usr

Copy libflashplayer.so to the appropriate browser plugins directory.
# cp libflashplayer.so /home/user_name/.mozilla/plugins

Copy the Flash Player Local Settings configurations files to the /usr directory
# sudo cp -r usr/* /usr

ls Command Sort by Date

Easy to list file with latest file on top.

# ls -lt   or


# ll -t

[root@D0n tmp]# ll -t
total 645876
drwxr-xr-x  2 root root       4096 Apr 24 02:54 din24
-rw-r--r--  1 Trg  users    302392 Apr 24 00:58 FLI-MAS1327
-rw-r--r--  1 Trg  users   2307179 Apr 24 00:57 d0n-MAS1327
-rw-r--r--  1 Trg  users   2307179 Apr 24 00:47 d0n-FFM2101
-rw-r--r--  1 Trg  users    302392 Apr 24 00:46 FLI.FFM2101
drwxr-xr-x  2 root root       4096 Apr 24 00:35 240413
-rw-r--r--  1 root root        756 Apr 20 04:02 logwatch

Find Large Files on Linux

# find / -type f -size +2000000k -exec ls -l {} \;

-rw-------  1 root root 3059384320 Mar 28 21:04 /usr2/SW/core.320
-rw-------  1 root root 3066548224 Mar 12 02:03 /usr2/SW/core.445

Command above will search and display files larger than 2,000,000 kB (2 GB)

# find / -type f -size +10000k -exec ls -l {} \; | sort +4 -nr

Command above will search and SORT by SIZE. Larger size on top to bottom.

How to Install Firefox 19.0.2 On CentOS 6.3

By default installation of CentOS, Firefox (old version) was already installed for you.

1) Verify previous Firefox installed on CentOS:
    #  rpm -qa | grep -i firefox

2) Remove old version of Firefox if exist:
    #  rpm -e --nodeps firefox

3) Download new version of Firefox into /opt directory.
    Let say we already download file firefox-19.0.2.tar.bz2. Next:
    # tar jxvf firefox-19.0.2.tar.bz2

4) Above step will extract tar.bz2 file to a directory firefox.

5) Make a link to the firefox directory:
    # ln -s /opt/firefox/firefox /usr/bin/firefox

Cannot Load to Linux OS When Change Motherboard

You probably need to make new initrd (kernel)

1) Boot with Linux rescue CD and let it search Linux installation

2) At rescue console,
    # chroot /mnt/sysimage
    # cd /boot ..where initrd located
    # mv /boot/initrd-2.4.21-32.EL.img /boot/initrd-2.4.21-32.EL.img.old ..rename old kernel image

3) Check /etc/modprobe.conf and make sure all drivers specified are accurate with new motherboard.

4) Rebuild existing initrd image:
    # /sbin/mkinitrd -v -f /boot/initrd-2.4.21-32.EL.img 2.4.21-32.EL

5) Reboot

Note: 2.4.21-32.EL is kernel version number

This is a guide only. I am also at beginner stage. Correct me if I'm wrong.

Analyze Core File

This is only for my notes. If you found it helps, feel free to read.

1) determine program that generate the core file
     # file <core>

2) determine library the program use
     # chatr <program>

3) version of library in core file
     # what <core>

4) stack trace
   # gdb <program> <core>
    (gdb) bt
   # dde -ui line <core> <program>
     dde > tb
   # adb

Capture Image with xwd Command

1) Capture using xterm window name:
     # xwd -root -name xterm_window_name > capture.xwd
     # xwud -in capture.xwd  (preview the image)

2) Capture using xterm id information:
     # xwininfo  (run this command and click on xterm window to get the id. e.g: 0x300fa8)
     # xwd -id 0x300fa8 > capture.xwd
     # xwud -in capture.xwd

3) Capture remote screen on the same LAN:
     # xwd -root -silent -display 192.168.1.103:0 > capture.xwd
     # xwd -root -silent -display computer1:0 > capture.xwd
     # xwd -root -display computer2:0 > capture.xwd  (beep appear at computer2 when command executed)
     # xwud -in capture.xwd

Note: You can convert xwd files to jpg, png or others format with Gimp application.


xterm Command Recorder:
     # script
     # exit
     # cat typescript

Install Dual Boot OS (Win XP + Linux)

Masalah
To install dual boot operation system with Win XP as default logon with CentOS Linux

Penyelesaian
1) Create 2 partitions
2) Install Win XP first on partition 1
3) Install CentOS on partition 2 and configure boot loader Linux to set default boot to Win XP.

Types of boot loader:
a) LILO - /etc/lilo.conf   |  /sbin/lilo -v -v
b) GRUB - /boot/grub/grub.conf

CPU % By Process State (Linux)

% us - percentage of time process execute in user mode
% sy - time process spent in system (kernel) mode
% ni - time spent executing in user mode under nice priority
% id - idle time
% wa - time spent waiting on I/O or timer
% hi - time spent servicing hardware interrupts
% si - servicing software interrupts

you can see this items with 'top' command

Add Timestamp to Your History

Just simple, use the following command on your xterm.

export HISTTIMEFORMAT='%F %T '

Just a Picture

CentOS LVM

 

My Notes...

zimbra (open source) webmail
wns hosting
mynic - register IP
www.softlabs.com.my