1. BIOS ->Do POST ->power on self test and Check boot priority,
2. MBR ->I stage boot loader,partition table, o/s signature
3. /etc/grub/grub.conf ->root (hd0,0)
kernel /vmlinuz...... ro root=LABEL=/
initrd /initrd.....img
4. /etc/inittab ->/etc/rc.d/rc.sysinit ->Set hostname
->check filesystem
->Enable root in rw mode
5. /etc/inittab ->runlevel ->/etc/rc.d/rcx.d (where x is num)
6. /etc/rc.d/rc ->whenever runlevel changes
7. /etc/rc.d/rc.local ->last script executed in boot process
GRUB FEATURES:
1. Grand unified boot loader
2. Grub indentifies upto 15 file systems
3. Grub has a pre-os enviornment use commands to load o/s
4. Grub supports LBA(Logical block addressing)
GRUB COMMANDS
1. root (hd0,0) ->mount the boot partition
2.find /etc/fstab ->find the partition which contains label of / 3.cat (hd0,4)/etc/fstab -> TO check label of root
OR
4.find /etc/fstab ->find the partition which contains label of /
5. root (hd0,4) ->Mount the route partiton
6. cat / + press tab ->shows contents of mounted partition
7. cat /etc/fstab ->open the file to see file contents
8. kernel /vmlinuz........ ro root=LABEL=/ ->Loads the kernel
9. initrd /initrd...img
10. boot
TO EXTRACT THE INITRD
1. mkdir initrd
2. cp /boot/initrd-2.6.18-53.el5.img initrd/
3. cd initrd/
4. ls
5. file initrd-2.6.18-53.el5.img
6. mv initrd-2.6.18-53.el5.img initrd.gz
7. ls
8. gunzip initrd.gz
9. ls
10.file initrd
11.cpio -ivd < initrd
TO SET GRUB PASSWORD
1.grub-md5-crypt
2.vim /etc/grub.conf ->open file (write below line in this file)
password --md5 <generated password> (write below hidden menu)
3.reboot
4.Try pressing e or c in grub prompt it wont let you unless you type p
and provide password
TO EXTRACT SPLASH IMAGE
1. mkdir splash
2. cp /boot/grub/splash.xpm.gz splash
3. cd splash/
4. ls
5. gunzip splash.xpm.gz
6. ls
7. firefox splash.xpm
TO ADD MULTIPLE TEXT TERMINAL
1. vim /etc/inittab
50:2345:respawn:/sbin/mingetty tty50 -->creates 50th terminal
2. init q
3. chvt 50
Note: To allow root to login also add entries to /etc/securetty.
TO MAKE SERVICE PERMANENT
1. chkconfig --list |grep network
2. chkconfig --list |grep sendmail
3. chkconfig --list |grep cups
4. chkconfig --list |grep vsftpd
5. chkconfig vsftpd on
6. chkconfig --list |grep vsftpd
7. chkconfig --levels 35 vsftpd on
chkconfig --levels 35 <service> <on/off>
If you found this post useful, I would really love it, if you can Like the Page, or share it with your Facebook/Google+/Twitter Friends... It will keep me motivated. Thank you!
No comments:
Post a Comment