Different Linux command @faced in Interview

>chage :-
chage (1) - change user password expiry information

amaresh@eOdissa-desktop:~$ chage -l amaresh
Last password change : Jul 08, 2009
Password expires : never
Password inactive : never
Account expires : never
Minimum number of days between password change : 0
Maximum number of days between password change : 99999
Number of days of warning before password expires : 7

>seq:-
seq (1) - print a sequence of numbers

amaresh@eOdissa-desktop:~$ seq 1 4
1
2
3
4
amaresh@eOdissa-desktop:~$ seq 1 2 6
1
3
5
amaresh@eOdissa-desktop:~$ seq 6
1
2
3
4
5
6
amaresh@eOdissa-desktop:~$ seq 1 3 9
1
4
7

>vmstat :-
vmstat (8) - Report virtual memory statistics

usage: vmstat [-V] [-n] [delay [count]]
-V prints version.
-n causes the headers not to be reprinted regularly.
-a print inactive/active page stats.
-d prints disk statistics
-D prints disk table
-p prints disk partition statistics
-s prints vm table
-m prints slabinfo
-S unit size
delay is the delay between updates in seconds.
unit size k:1000 K:1024 m:1000000 M:1048576 (default is K)
count is the number of updates.

Q:What command do you use to get the information about disk statistics?
Ans:- vmstat -d

amaresh@eOdissa-desktop:~$ vmstat -d
disk- ------------reads------------ ------------writes----------- -----IO------
total merged sectors ms total merged sectors ms cur sec
ram0 0 0 0 0 0 0 0 0 0 0
ram1 0 0 0 0 0 0 0 0 0 0
ram2 0 0 0 0 0 0 0 0 0 0
ram3 0 0 0 0 0 0 0 0 0 0
ram4 0 0 0 0 0 0 0 0 0 0
ram5 0 0 0 0 0 0 0 0 0 0
ram6 0 0 0 0 0 0 0 0 0 0
ram7 0 0 0 0 0 0 0 0 0 0
ram8 0 0 0 0 0 0 0 0 0 0
ram9 0 0 0 0 0 0 0 0 0 0
ram10 0 0 0 0 0 0 0 0 0 0
ram11 0 0 0 0 0 0 0 0 0 0
ram12 0 0 0 0 0 0 0 0 0 0
ram13 0 0 0 0 0 0 0 0 0 0
ram14 0 0 0 0 0 0 0 0 0 0
ram15 0 0 0 0 0 0 0 0 0 0
sr0 0 0 0 0 0 0 0 0 0 0
sda 129824 12599 1675591 430108 108073 14333 979288 2993424 0 36


Q:What command do you use to get the information about disk table?
Ans:-vmstat -D

amaresh@eOdissa-desktop:~$ vmstat -D
18 disks
5 partitions
129824 total reads
12599 merged reads
1675591 read sectors
430108 milli reading
107383 writes
13450 merged writes
966704 written sectors
2990880 milli writing
0 inprogress IO
366 milli spent IO

Q:What command do you use to get the information about no of forking ?
Ans:- vmstat -f

amaresh@eOdissa-desktop:~$ vmstat -f
11008 forks


>What command do you use to create swap space?

Unix Interview questions (sed)

> remove first column of a space delimited txt
how to remove the first column of a space delimited txt file? there are 12+ columns... what is the cleanest way?

cut -d\ -f4-
OR
cat | cut -d\ -f4-
OR
sed -e 's/^[ \t]*//' filename

>delete 7th column in unix,

cut -f1-6,8- filename

>how to remove spaces in a string using sed.

`echo "$infilename" | sed 's/^ *//;s/ *$//`

>replace space or spaces in a line of a file with a single :

sed -e 's/\s/:/g'

>sed : remove whitespace

sed 's/ $//' file1.txt > file2.txt # Remove the last space at eol
sed 's/ *$//' file1.txt > file2.txt # Remove all spaces at eol

>To remove all whitespace (including tabs) from left to first word, enter:

cat | sed -e 's/^[ \t]*//'

Where,

* s/ : Substitute command ~ replacement for pattern (^[ \t]*) on each addressed line
* ^[ \t]* : Search pattern ( ^ - start of the line; [ \t]* match one or more blank spaces including tab)
* // : Replace (delete) all matched pattern

Some Network Linux Commands...

How will you get only TCP protocol status in a network?

Ans:- # netstat -t
O/P:-
root@eOdissa-desktop:/home/amaresh/Documents/Testing# netstat -t
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 eOdissa-desktop.l:59156 www-sf2p-a.facebook:www ESTABLISHED
tcp 0 0 eOdissa-desktop.l:59175 www-sf2p-a.facebook:www ESTABLISHED
tcp 0 0 eOdissa-desktop.l:57170 px-in-f83.google.co:www ESTABLISHED
tcp 0 0 eOdissa-desktop.l:45271 pv-in-f100.google.c:www ESTABLISHED
tcp 0 0 eOdissa-desktop.l:41356 a96-17-8-64.deploy.:www ESTABLISHED
tcp 0 0 eOdissa-desktop.l:52631 a96-17-8-48.deploy.:www ESTABLISHED
tcp 0 0 eOdissa-desktop.l:41932 ord-qs2-n24.panther:www ESTABLISHED
tcp 0 0 eOdissa-desktop.l:54438 px-in-f154.google.c:www ESTABLISHED
tcp 0 0 eOdissa-desktop.l:54442 px-in-f154.google.c:www ESTABLISHED
tcp 0 0 eOdissa-desktop.l:56950 a96-17-69-27.deploy:www ESTABLISHED
tcp 0 0 eOdissa-desktop.l:56949 a96-17-69-27.deploy:www ESTABLISHED
tcp 0 0 eOdissa-desktop.l:56948 a96-17-69-27.deploy:www ESTABLISHED
tcp 0 0 eOdissa-desktop.l:56947 a96-17-69-27.deploy:www ESTABLISHED
tcp 0 0 eOdissa-desktop.l:53859 221x247x49x219.ap:34580 ESTABLISHED

How will you get only UDP protocol status in a network ?
Ans:- # netstat -u
O/P:-
root@eOdissa-desktop:/home/amaresh/Documents/Testing# netstat -u
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State

How will you find only listening socket information?
Ans:- #netstat -l
O/P:-
root@eOdissa-desktop:/home/amaresh/Documents/Testing# netstat -r
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
192.168.152.128 * 255.255.255.128 U 0 0 0 tap0
192.168.1.0 * 255.255.255.0 U 0 0 0 eth0
link-local * 255.255.0.0 U 0 0 0 eth0
192.168.0.0 192.168.152.129 255.255.0.0 UG 0 0 0 tap0
172.16.0.0 192.168.152.129 255.240.0.0 UG 0 0 0 tap0
default 192.168.1.1 0.0.0.0 UG 0 0 0 eth0

How will you get the class of any IP ?
Ans:- ipcals ( install apt-get install ipcalc in debian linux)

O/P:-
root@eOdissa-desktop:/home/amaresh/Documents/Testing# ipcalc 192.168.1.143
Address: 192.168.1.143 11000000.10101000.00000001. 10001111
Netmask: 255.255.255.0 = 24 11111111.11111111.11111111. 00000000
Wildcard: 0.0.0.255 00000000.00000000.00000000. 11111111
=>
Network: 192.168.1.0/24 11000000.10101000.00000001. 00000000
HostMin: 192.168.1.1 11000000.10101000.00000001. 00000001
HostMax: 192.168.1.254 11000000.10101000.00000001. 11111110
Broadcast: 192.168.1.255 11000000.10101000.00000001. 11111111
Hosts/Net: 254 Class C, Private Internet

root@eOdissa-desktop:/home/amaresh/Documents/Testing#ipcalc 192.168.0.1 255.255.128.0 255.255.192.0
Address: 192.168.0.1 11000000.10101000.0 0000000.00000001
Netmask: 255.255.128.0 = 17 11111111.11111111.1 0000000.00000000
Wildcard: 0.0.127.255 00000000.00000000.0 1111111.11111111
=>
Network: 192.168.0.0/17 11000000.10101000.0 0000000.00000000
HostMin: 192.168.0.1 11000000.10101000.0 0000000.00000001
HostMax: 192.168.127.254 11000000.10101000.0 1111111.11111110
Broadcast: 192.168.127.255 11000000.10101000.0 1111111.11111111
Hosts/Net: 32766 Class C, Private Internet

Subnets after transition from /17 to /18

Netmask: 255.255.192.0 = 18 11111111.11111111.11 000000.00000000
Wildcard: 0.0.63.255 00000000.00000000.00 111111.11111111

1.
Network: 192.168.0.0/18 11000000.10101000.00 000000.00000000
HostMin: 192.168.0.1 11000000.10101000.00 000000.00000001
HostMax: 192.168.63.254 11000000.10101000.00 111111.11111110
Broadcast: 192.168.63.255 11000000.10101000.00 111111.11111111
Hosts/Net: 16382 Class C, Private Internet

2.
Network: 192.168.64.0/18 11000000.10101000.01 000000.00000000
HostMin: 192.168.64.1 11000000.10101000.01 000000.00000001
HostMax: 192.168.127.254 11000000.10101000.01 111111.11111110
Broadcast: 192.168.127.255 11000000.10101000.01 111111.11111111
Hosts/Net: 16382 Class C, Private Internet


Subnets: 2
Hosts: 32764

How will you monitor your LAN IP?
Ans:- iptraf (use apt-get install iptraf in debian linux)

How will you get your bandwidth usages of your interface by host ?
Ans:- iftop

JOb for .Net as well as C/C++

Hi,

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Kindly refer your friends who have worked on .net desktop applications.
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Please forward this to your friends.

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Thanks & Regards
Jeet