1. What is ldd?
List dynamic dependencies – print
shared library dependencies
Eg: – # vim new.c
# gcc new.c –o new
# ldd new
2. What is the command to uninstall
processes in Linux?
rpm –e sendmail
-e – remove
3. What is the command for finding the
highest memory occupied file in Linux?
du –ah / | sort –n –r | head –n 1
du – estimate file space usage
-a – write counts for all files, not
just directories
-h – print sizes in human readable
format (eg. 1K 234M 2G)
sort – sort lines of text files
-n – compare according to string
numerical value
-r – reverse the result of comparisons
head – output the first part of files
-n – number of lines
4. What are the Linux boot files?
1./boot/grub/grub.conf: contains boot
disk parameters
2./etc/fstab: contains File systems
which need to mount at boot time
3./etc/initab: Contains default run
level
4./etc/init.d/rc.d/rcN.d: This is a
dir it contains
5. Difference between swap partition
and swap file?
Swap partition is maintained as a
separate partition. Same swap partition can be used for two OS within single
machine.
Suppose if the system crashes, there
is a chance to recover or it may not
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
the system crashes then there is a huge chance to lost the swap file
system.
6. A file which is not deleted by
normal user and also root (using rm), for that type of file how we delete it?
Using chattr command, we need to
change the attributes and then we remove using rm command.
Eg: – chattr -iIu example
rm -rf example
7. Difference between nfs soft and
hard mounting points?
Hard mount option: – If the client
fails to access the server, then the connection hangs and once the system is up
then it will again access the server.
Soft: – If the client failed to
connect the server, it immediately gives the error report and closes the connection.
8. If we transfer 100 files by ftp to
remote server, how to know the files are successfully transfer or some file are
not transferred?
ftp>mput 1 2 3 …. 100
ftp> ls –l
9. I know ssh, telnet, dns,apache all
are worked on TCP/UDP but i want to know any one service which are working on
UDP only?
snmptrap 162/udp
snmptrap – simple network management
protocol trap
snmptrapd is an SNMP application that
receives and logs
10. I want to built a fire wall using
iptables. My condition is ” inbound to 192.168.0.2 with a port of 80 from
172.168.0.1 should accept”
iptables –A INPUT –p tcp –dport 80 –s
172.168.0.1 –d 192.168.0.2 –j ACCEPT
11. I want to see how many interfaces
(Ethernet cards) are working using single command?
ifconfig
12. What is the status code 403,404
represented in apache server?
403 represent forbidden error, means
if a file misses some selinux security context.
404 represent that there is a cgi
script missing or web pages missing.
13. How to monitor ports in a linux
machine, with single command?
nmap localhost
14. In my linux machine, i lost
/etc/passwd file and /etc/shadow file, then how can i recover it?
Normally in linux we must have backup
by default for /etc/passwd and /etc/shadow files
/etc/passwd —> /etc/passwd-
/etc/shadow —> /etc/shadow-
from there we can copy or restore. If
both are not available. Then follow below steps:
1. reboot
2. Single user mode [ single
init=/bin/bash ]
3. pwconv
4. check /etc/passwd and /etc/shadow
files are there
5. sync
6. init 3 or reboot with init 3
15. what r the different command to
check ram,process and hdd of linux machine
To check ram in your system:
#free
To check process
#ps
#top
To check hdd
#fdisk
#sfdisk -l
16.If i run ls command it will show me
the junk output what is problem and how to resolve it
Set your terminal setting by stty and
before that, export ls command to PATH variable
17. WHAT IS THE MEANING OF AIX
AIX (Advanced Interactive eXecutive)
is an open operating system from IBM which is based on a version of UNIX.
AIX/ESA was designed for IBM’s System/390 or large server hardware platform.
AIX/6000 is an operating system that runs on IBM’s workstation platform, the
RISC System/6000.
18. Why ls -F dev/log file output
indicate as = sign at end of the file name?
Standard output
19. What is nis server?
NIS is a service that provides any
user on a network with the same working environment irrespective of the system
on that network, which has been used for login purpose.
For example if NIS server is set up in
a single system and configured to hold user accounts and their passwords and
access information. Then any user on that network can login to his/her account
from any system (with nis client running) on that configured network. This
gives a look and feel that the user is logged into his/her own system. But
actually it’s the account on the NIS server that is mounted on the local sytem
user login.
20. What command can you use to review
boot messages?
Dmesg
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