Linux Interview Questions with answers :

 1)..
what is the umask in linux os ?
umask is the file permission .
whenever the file or directory is created , automatically the umask value is assigned 
like umask value is 022 ,0022 and 077
if you want to change default umask value into linux os ,
we can go to change the vi /etc/login.defs file 

2). what is the inode number in linux os ?
its contains the file information . 
whenever the file is created automatically inode number assigned to this file
if you want to check the inode number into this file:
ll -li command 
in this way we can get this inode number 

3).How to disable the root account in linux os ?
usermod -s /sbin/nologin root 
in this way we can disable the root account in linux os 
4).
what is linux boot process :
bios 
mbr
grub
kernel
init 
runlevesl
5).
what is the difference between curl and wget command in linux os ?
curl - checking the connectivity .wheather the connection is not established or not
wget - using this command we can download the files from server side 

6).
what are the possible causes one no might be able to access server via ssh?
username ,password 
keys mismatch
port not allowed for security groups 
ipaddress
networkacl rules 
ipaddress 

7)..
what is rpm for /etc/resolv.conf
rpm -qf /etc/resolv,conf 
its owned by network manager 
8)..
what are the runlevles in linus os ?

runlevel 0 - shutdown the system
runlevel 1 - single user mode
runlevel2 - multiuser mode with no nfs
runlevel 3 - multiuser mode with no gui 
runlevel 4 - user definable
runlevel 5 - multiusermode with gul
run level 6 - reboot the system 

9).
what is epel ? what is the used for this ?
extra package enterprise linux .
which is used to intsall and download the packages from which do not come from ios 
using this packages to reinstall the linux os 

10)..

what is the difference between /dev/zero and /dev/null?
first go to the directiry called as the 
cd /dev/
then execute the command like as the,
file zero 
its shows special chanrter is : 1/5
file null 
its shows special charater : 1/3
dev/zero and /dev/null :
/dev/zero : its produces no ouput 
/dev/null : its used to crate the empty file or swap 





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