Linux Commands

hard mount option:- If the client fails to access the

server,then connection hang it, after the system up then it

access the server.

Soft:- If the client failed to connect the server it

immediately gives the error report, and close the connection.

after transferring the files look into the present working

directory of the client machine for the transferred files

and cross check it.

else you can check the total number of files transferred to

the client machine in present working directory using this

command

ls -l | wc -l

BOOTPS (67port number)

BOOTPC(68 port number)

belongs to DHCP

#ifconfig -a

except loopback

403 represent forbidden error, means if files misses some

selinux security context is missing.

404 represent that their is a cgi script missing or web

pages missing.

nmap is not the default available command.we can use netstat

netstat -nl, netstat -nltp ,netstat -nulp

Swap partition maintained seperate partition.

same swap partition can be used in two OS within single

machine.

If system crashes their is a chance to recover itor may not

be corrupt the partition.

Less fragmented.

where as swap file takes very less space. we can increase

the space very easily, compared to swap partition.

SWap file system fragmented.

If system crashes their is a huge chance to lost the swap

file system.

#uname -a

we get the information about os

and Regarding CPU

#grep flags /proc/cpuinfo

if cpu is in

Long mode - 64 bit CPU

Real mode 16 bit CPU

Protected Mode is 32-bit CPU

Login into single user mode and try below things:

1. passswd [ Change Password for root ]

2. rm -rf /etc/nologin

3. remove any "nologin" shell for root user in /etc/passwd file

4. chage -l root then chage -E root

5. passwd -u root

6. chattr -i /etc/passwd /etc/shadow

7. chmod 600 /etc/securetty

8. vim /etc/rc.local --> then remove any line like say "

/etc/nplogin "

9. chsh root [ /bin/bash ]

RAM : We will check RAM, Process as well as HDD by the root

user...

RAM : #free

#cat /proc/meminfo

Process : ps -a -> It will show running process within all

terminals..

Hard Disk : #fdisk -l

LILO (LInux LOader) is a boot loader (a small program that

manages a dual boot) for use with the Linux operating system.

Most of the new computers are shipped with boot loaders for

some version of Microsoft Windows or the Mac OS. If a

computer is to be used with Linux, a special boot loader must

be installed. LILO is the most popular boot loader among

users.

#pwconv

-> It convert /etc/passwd to /etc/shadow

#pwunconv

-> It convert /etc/shadow to /etc/shadow

you can check both file after running pwconv and pwunconv

cmd to get difference.

dmidecode | less

we need to create raid level 1 in linux. and create a

backup of data.

Emulex HBA Adaptor.

Find the WWPN.

Step1:

Confirm if the HBA is Emulex.

# lspci

......

0e:00.0 Fibre Channel: Emulex Corporation Zephyr LightPulse

Fibre Channel Host Adapter (rev 02)

17:00.0 Fibre Channel: Emulex Corporation Zephyr LightPulse

Fibre Channel Host Adapter (rev 02)

#

Step2:

# cd /sys/class/fc_host/

# ls -l

total 0

drwxr-xr-x 3 root root 0 Oct 14 20:57 host0

drwxr-xr-x 3 root root 0 Oct 14 20:57 host1

# cat port_name

0x10000000c97a37cf

#

By using chmod command

for example chmod 777 <file name>

its for full permissionof the file

read =4

write =2

execute=1

user group other

7 7 7

4+2+1 4+2+1 4+2+1

r+w+e r+w+e r+w+e

other example

we give permission to user to full and give group and other

to only read and execute than

chmod 755 <file name>

whenever you want restart Apache web server without shutdown

Apache web server that time you use the commands service

httpd reload ,if you type the commands service httpd restart

that time frist shut down the service then startup the

service but if you type commands service httpd reload, only

read the configuration file and startup the service

The chainloading technique tells GRUB to read +n sectors from

the start of the partition. Usually n = 1. The chainloading

command may specify also a file name: chainloader +1 read 1

sector from start of the partition

chainloader /boot/chain.os2 load a file

grub> unhide (hd0,0)

grub> hide (hd0,1)

grub> rootnovery (hd0,0)

grub> chainloader +1

grub> makeactive

grub> boot