Python difference between list copy and reference

inspiring_ppl = ["Mahatma Gandhi", "Mother Teresa", "Paul Coelho", "Bill Gates", "Steve Jobs"]

#The following Shares same memory location
inspiring_ppl_1 = inspiring_ppl

inspiring_ppl.append("Abdul Kalam")
inspiring_ppl_1.append("Abraham Lincoln")

#Therefore inspiring_ppl, inspiring_ppl_1 contains the same contents including "Abdul Kalam" and "Abraham Lincoln"

#Python does not have variables like C 
#In Python variables are just tags attached to objects

#The following shares different memory location
inspiring_ppl_2 = inspiring_ppl[:]

inspiring_ppl.append("Swami Vivekananda")

print(inspiring_ppl)
o/p: ["Mahatma Gandhi", "Mother Teresa", "Paul Coelho", "Bill Gates", "Steve Jobs", "Abdul Kalam", "Abraham Lincoln"]

print(inspiring_ppl_1)
o/p: ["Mahatma Gandhi", "Mother Teresa", "Paul Coelho", "Bill Gates", "Steve Jobs", "Abdul Kalam", "Abraham Lincoln"]

print(inspiring_ppl_2)
o/p: ["Mahatma Gandhi", "Mother Teresa", "Paul Coelho", "Bill Gates", "Steve Jobs", "Swami Vivekananda"]

Check an element exists in an array/list in Python

inspiring_ppl = ["Mahatma Gandhi", "Mother Teresa", "Paul Coelho", "Bill Gates", "Steve Jobs"]


#raw_input(), print for Python 2.X Version 
#input(), print() for Python 3.X Version 

another_person = input("Enter person Name : ")

if another_person in inspiring_ppl:
    inspiring_ppl.remove(another_person)
else:
    inspiring_ppl.append(another_person)

print(inspiring_ppl)

How to copy a list into another

inspiring_ppl = ["Mahatma Gandhi", "Mother Teresa", "Paul Coelho", "Bill Gates", "Steve Jobs"]

more_inspiring_ppl = inspiring_ppl[:]

more_inspiring_ppl.reverse()

print inspiring_ppl       #2.X Version
#print (inspiring_ppl)  #3.X Version

print more_inspiring_ppl   #2.X Version
#print (more_inspiring_ppl)   #3.X Version

For Loop in Python

inspiring_ppl = ["Mahatma Gandhi", "Mother Teresa", "Paul Coelho", "Bill Gates", "Steve Jobs"]

for person in inspiring_ppl:
    print "Hello", person + ", how are you?"  #3.X Version
     #print("Hello", person + ", how are you?")  #2.X Version

Reading a File with line numbers

file = open("read.txt","r")
text = file.readlines()
file.close()

counter = 1
for line in text:
    print counter, line,
    counter = counter +1
print

File Operations in Python

file = open("read.txt","r")
text = file.readlines()    #Read lines from read.txt
file.close()

file2 = open ("write.txt", "w")
#Write all lines from read.txt into write.txt
#It overrides if any content already present in write.txt
file2.writelines(text)
file2.close

file2 = open ("append.txt", "a")
#It appends content from read.txt into append.txt
file2.writelines(text)
file2.close

Print File Content in Python

file = open("read.txt","r")
text = file.readlines()   #Reads the file content
file.close()

for line in text:
    print line        #Python 2.X Versions
    #print(line)      #Python 3.X Versions

Print File in Reverse Order in Python

file = open("read.txt","r")
text = file.readlines()   #Reads the file content
file.close()

text.reverse()    #It reverses the content

for line in text:
    print line        #Python 2.X Versions
    #print(line)    #Python 3.X Versions

Unix Shortcuts 1

a) !!    #to run the previous command 

e.g.,
>>pwd
>>!!  #executes "pwd" command

b) Control+P #move up through history list, one command at a time. (Up arrow key) 

c) Control+N #move down (or Down arrow key). 

d) !n #run nth command in history list. where n is a number from your history list. 

e.g.,
>>history

1 ls
2 pwd
3 vim test.txt
4 vim ~/aliases
5 vim ~/.vimrc
6 history

>>!3 #runs 3rd command in the history i.e., vim test.txt
>>!-2 #runs 2nd command from the end of history i.e., vim ~/.vimrc

e) !n:p   #only preview command number n (will not execute the command). 

f) !string   #Run most recent command starting with characters in string.

e.g.,

>>vim text.txt
>>pwd
>>ls -lrt
>>mkdir test
>>!vim     press<Enter> #Runs most recent command starting with "vim"
>>!ls press<Enter> #Runs most recent command starting with "ls"

g) Move the cursor to beginning of line in Unix Terminal
Beginning of line     Ctrl+a

h) Move the cursor to end of line in Unix Terminal
End of line           Ctrl+e

Find Files Using a Wildcard in UNIX

- Find command checks recursively in all the folders present with in that path

find files ending with "py" in current directory recursively
find . -iname \*.py

find files starting with prel_log in "/" directory recursively
find / -name perl_log\* -print

- The backslash \ character is important
- It tells the shell not to treat the wildcard character as a wildcard.

Execte the Perl script within the edited perl file

Suppose you edited a perl file in Vim editor
You can execute the perl script there itself without going back to command prompt, which saves you time

e.g.,

vim test.txt

press <Escape>
! perl %

- It executes the script which already edited

- if you want to execute a different script, mention the file name

press <Escape>
! perl test2.txt


- press Enter again to return to the edited file

vim edit multiple files

How to open multiple files in different tabs in Vim

]# vim -p file1.txt file2.txt file3.txt



How to access multiple files from the same window 

]# vim  test_1.txt        #Which opens test_1.txt

After editing this file, without closing or coming out of this file, do you know how to reopen a file.

:e test_2.txt       #Which opens test_2.txt

Now you want to reopen the previous file test_1.txt

:e#                 #Now you have already opened test_2.txt, but this reopens test_1.txt

after this, if you try to give the command again, it reopens previous file test_2.txt

:e#                 #Now you have already opened test_1.txt, but this reopens test_2.txt


Suppose if you want to open some other file, just give the file name and access
:e  test_3.txt


This trick helps you a lot when you have to work switching back to back two files and this way you can easily reopen the previous file without much typing effort


Want to learn more about Vim/Vi Commands, please refer to the following:
http://perlexamples.blogspot.mx/2012/11/vim-commands.html

Unix How to Find a Particular Directory

We know how to find a file in Unix directories using

This will search sample.txt in current directory

#]find . -iname sampe.txt


But if we want to find out a particular directory in the unix, type -d denotes search for directory

#] find / -name mysql -type d
/var/log/mysql
/var/lib/mysql
/var/lib/mysql/mysql
/etc/mysql
/usr/lib/perl5/DBD/mysql
/usr/lib/perl5/auto/DBD/mysql
/usr/share/mysql


In order to narrow down the search, you could mention exact path (/etc) where you want to search

#] find /etc -name mysql -type d
/etc/mysql

Unix For Loop

#]mkdir for_test_dir1

#]mkdir for_test_dir2

#]mkdir for_test_dir3

#]cat for_test_dir1/for_test.txt
content 1
content 1
content 1

#]cat for_test_dir2/for_test.txt
content 2
content 2
content 2

#]cat for_test_dir3/for_test.txt
content 3
content 3
content 3
...
...

#] ls
for_test_dir1 for_test_dir2 for_test_dir3 for_test_dir4 for_test_dir5
......
......


#]foreach var (`ls`)
foreach? ls -ltr $var/for_test*
foreach? end

O/P:
It will list all the for_test files present in for_test_dir's

pushd popd example

When you have  to work with navigate different directories quickly, its difficult to remember the whole path or type the whole thing again and again.

There is concept in Linux/Unix to manipulate directory stack, you can use directory stack to push directories into it and later pop directory from the stack.

1) dirs : Display the current directory stack without pushing or popping a new directory

2) pushd : Push directory into the Stack

3) popd : Pop directory from the Stack

Using pushd and popd effectively can help you get around your command-line environment quickly


E.g.,

]# mkdir /usr/local/dir1

]# mkdir /usr/local/dir2

]# mkdir /usr/local/dir3

]# dir
~

]# pushd /usr/local/dir1

]# dir
/usr/local/dir1   ~


]# pushd /usr/local/dir2


]# dir
/usr/local/dir2   /usr/local/dir1   ~

]# pushd /usr/local/dir3

]# dir
/usr/local/dir3   /usr/local/dir2   /usr/local/dir1   ~


]# popd

]# pwd
/usr/local/dir3

]# dir
/usr/local/dir2   /usr/local/dir1   ~


]# popd

]# pwd
/usr/local/dir2

 ]# dir
/usr/local/dir1   ~


]# popd


]# pwd
/usr/local/dir1

 ]# dir
~

How to find the size of a directory in linux

We all know "du" command gives the size of the files, but it not convenient to read or understand the size as "du" command gives the size in KB's

In order to  make is human readable format, please follow as mentioned below


du -lsh <directory_name>

du -lsh <file_name>

-h => display the size in human readable format

e.g.,
>> du  -lsh  prabhath_movies
5GB  prabhath_movies

>> du  -lsh  hero.avi
1GB   hero.avi


Thanks for going through this article, Have a good day :-)

Vim Commands

1) How to open file in VI Editor at a specific line

]#  vi  Sample.txt  ++105

ie., From the linux terminal, it will open the Sample.txt  at line 105

2) How can we search word that is under the cursor in VI/VIM

Put the cursor on the word
Press " * " for the next occurrence of the word

3)  a) Replace a pattern with another pattern from line "m" to line "n"

>>cat test.txt

...
49 prabhath kota
50 lakshmi muvvala
51 vamsidar kota
52 prabhath kota
53 prabhath prabhath
54 perl awk
55 prabhath prabhath
56 kota prabhath
...

:50,55s/prabhath/darling/
#It replaces line 50 to line 55, only the first occurance in the line

o/p:

...
49 prabhath kota #49th line
50 lakshmi muvvala
51 vamsidar kota
52 darling kota
53 darling kota
54 perl awk
55 darling kota      //replaced only first occurance
56 kota prabhath #56th line
...


>>cat test.txt

...
49 prabhath kota      #49th line
50 lakshmi muvvala
51 vamsidar kota
52 prabhath kota
53 prabhath prabhath    //replaced all
54 perl awk
55 prabhath prabhath   //replaced all
56 kota prabhath          #56th line
...


:50,55s/prabhath/darling/g
#It replaces line 50 to line 55, all the occurances in the line

o/p:

...
49 prabhath kota #49th line
50 lakshmi muvvala
51 vamsidar kota
52 darling kota
53 darling darling
54 perl awk
55 darling darling
56 kota prabhath #56th line
...


3 b) Replace a pattern with another pattern replacing through out the file

:%s/prabhath/prabhath12345/g


3 c) Replace a pattern with another pattern from the current line to next "n" lines

e.g.,

>> cat test.txt
test test test test
test test test test

#if the cursor is on the 2nd line ("." denotes 2nd line)
#if the cursor is on the 1st line ("." denotes 1st line)

:.,.+2s/test/testabc


o/p:

testabc test test test
testabc test test test


:.,.+2s/test/testabc/g
# "g" is for all the occurances in the current line

o/p:

testabc testabc testabc testabc
testabc testabc testabc testabc


4) To remove the last character from every line in the file. 

Use it if every line in the file ends with ^M as the result of a file transfer.
Execute it when the cursor is on the first line of the file.

:%s/.$//

Note:
$ -> denotes end of the line
^ -> denotes start of the line


5) To remove the first character from every line in the file. 

:%s/^.//

Note:
$ -> denotes end of the line
^ -> denotes start of the line



6) How to search in Vim

" Show all tabs:

/\t


" Show and Replace trailing(ending) whitespace:

:%s/\s\+$//gc


" Show spaces before a tab:

/\+\ze\t



7) Edit new file from the current viewing of the file...

Suppose you already opened test.txt, suppose you are trying to open new.txt now..

gvim test.txt

after that you want to close test.txt and open new.txt, then you can do like...

:e new.txt




8) How to access multiple files from the same window 

]# vim  test_1.txt         #Which opens test_1.txt

After editing this file, without closing or coming out of this file, do you know how to edit another file from the same window

:e test_2.txt      #Which opens test_2.txt

Now you want to go reopen the previous file test_1.txt

:e#                  #Now you have already opened test_2.txt, but this reopens test_1.txt

after this, if you try to give the command again, it reopens previous file test_2.txt

:e#                  ##Now you have already opened test_1.txt, but this reopens test_2.txt


This trick helps you a lot when you have to work switching back to back two files and this way you can easily reopen the previous file without much typing effort



9) How to Split screen

Horizontally:

vi test.txt

:split new.txt


Vertically:

vi test.txt

:vsplit new.txt

Note:
Cntrl + ww //To change the window from one to another


9) Move the cursor to beginning of line in Vim Editor

$ takes you to the end of the line


10) Move the cursor to beginning of line in Vim Editor


^ takes you to the first non-whitespace character in the line, and

0 (zero) takes you to the beginning of the line including whitespace

Cron Job Basics - Crontab

crontab -e      Edit your crontab file, or create one if it doesn’t already exist.
crontab -l      Display your crontab file.
crontab -r      Remove your crontab file.
crontab -v      Display the last time you edited your crontab file. (This option is only available on a few systems.)


min    0-59
hour   0-23
day    1-31
mon    1-12
dow    0-6 (Sunday = 0, Saturday = 6) DOW => Day of Week


min hr day month Week
30 00 01 01,06,12 * –> 00:30 Hrs on 1st of Jan, June & Dec.
00 20 * 10 01-05 –> 8.00 PM every weekday (Mon-Fri) only in Oct
00 00 01,10,15 * * –> midnight on 1st ,10th & 15th of month
05,10 00 10 * 01 –> At 12.05,12.10 every Monday & on 10th of every month
05 00 01 01 * -> 00:05 Hrs on 1st of Januray of each year

The asterisk in the field indicates to cron that any day of the week is acceptable.
However, since an explicit month and day have been specified, the day of the week is effectively ignored.


How to create a cron job that will run on the last day of each month, considering the fact that a month could have 28, 29, 30 or 31 days ?

Ans:
Your script, however, can test for that and exit if it is not the last day.
So - you'd set it in cron to run on the 28, 29, 30 and 31. Your script decides if it really is the last day and exits if it is not.
Or you can put each month into crontab separately and just deal with February in your script.


min hr day month Week
30 20 28,29 02 * /usr/prabhath/run.pl -> 8.30 PM every 28th of Feb
30 20 30 04,06,09,11 * /usr/prabhath/run.pl -> 8.30 PM every 30th of Months having 30 days
30 20 31 01,03,05,07,08,10,12 * /usr/prabhath/run.pl -> 8.30 PM every 31th of Months having 31 days

More Examples:
################
min hr day month Week User Command
01 * * * * root echo "This command is run at one min past every hour"
17 08 * * * root echo "This command is run daily at 8:17 am"
17 20 * * * root echo "This command is run daily at 8:17 pm"
00 04 * * 0 root echo "This command is run at 4 am every Sunday"
42 04 01 * * root echo "This command is run 4:42 am every 1st of the month"
01 * 19 07 * root echo "This command is run hourly on the 19th of July"


Example:
############
min hr day month Week User Command
* 12 16 * Mon root cmd

Will run cmd at midday every Monday and every 16th, and will produce the
same result as both of these entries put together would:
* 12 16 * * root cmd
* 12 * * Mon root cmd

Example:
############

min hr day month Week User Command
59 11 * * 1,2,3,4,5 root backup.sh
equals to
59 11 * * 1-5 root backup.sh


Step Values:
#################
Cron also supports 'step' values.
*/2 in the dom field would mean the command runs every two days and likewise,
*/5 in the hours field would mean the command runs every 5 hours.

Example:
############

min hr day month Week User Command
* 12 10-16/2 * * root backup.sh
is the same as:
* 12 10,12,14,16 * * root backup.sh

E.g.,

min hr day month Week User Command
*/15 9-17 * * * root connection.test
Will run connection.test every 15 mins between the hours or 9am and 5pm


min hr day month Week User Command
* 12 1-15,17,20-25 * * root cmd
Will run cmd every midday between the 1st and the 15th as well as the 20th and 25th (inclusive) and also on the 17th of every month.


O/P from Cron:
###################

min hr day month Week User Command
*/15 9-17 * * * root connection.test | mail -s "Subject" prabhathkota@gmail.com

*/15 9-17 * * * root connection.test >/dev/null 2>&1 #It won't send mail to anyone

*/15 9-17 * * * root connection.test > log.file

*/15 9-17 * * * root connection.test > log.file 2>&1

*/15 9-17 * * * root connection.test > mail -s "logfile for cmd" <log.file

*/15 9-17 * * * root connection.test >


Disable Email in Cronjob
#########################
By default cron jobs sends a email to the user account executing the cronjob. If this is not needed put the following command At the end of the cron job line .
>/dev/null 2>&1

Word Count - Unix

>> wc test.txt

15  43 282 test.txt

ie.,

15 lines
43 words
282 chars


>>wc -l test.txt    #Lines
15 test.txt


>> wc -c test.txt    #Words
282 test.txt


>> wc -w test.txt    #Characters
43 test.txt

How to print first two columns of a file - AWK

1) It will print first line alone

>>awk 'NR==1' test.txt #1st line from the top
>>awk 'NR==7' test.txt #7th line from the top

2) How to print first line/lines of the file

>>head -8 test.txt

How to print last two columns of a file - AWK

1) How to print last two columns of a file?

NF => prints the last line

>>cat test.txt
prabhath   kota   Jan
lakshmi     muvvala   Feb
PRABHATH    KOTA   Mar
LAKSHMI       MUVVALA   Apr

>>awk '{print $(NF-1),"\t",$NF}' test.txt #RIGHT

output:
kota              Jan
muvvala         Feb
KOTA           Mar
MUVVALA  Apr

>>awk '{print $NF-1,"\t",$NF}' test.txt #WRONG


2) How to print last two columns of a command?

>> ls
-rw-r----- 1 kotaprax users 203 Nov 22 12:51 a.txt
-rw-r----- 1 kotaprax users 282 Nov 23 10:18 b.txt
-rw-r----- 1 kotaprax users  17 Nov 16 15:25 c.txt

>>ls -l | awk '{print $(NF-1),"\t",$NF}'

output:
12:51 a.txt
10:18 b.txt
15:25 c.txt


3) How to print the last line/lines of the file

>>tail -f test.txt
>>tail -4 test.txt #Prints Last 4 lines
>>tail -1 test.txt #Prints Last line of the file

Awk Examples

1) To fetch selected columns from a command using AWK

e.g.,

>> ls -l

-rw-r----- 1 kotaprax users 203 Nov 22 12:51 new.txt
-rw-r----- 1 kotaprax users 100 Nov 22 12:51 new1.txt
-rw-r----- 1 kotaprax users 126 Nov 23 12:57 output.txt
-rw-r----- 1 kotaprax users 282 Nov 23 10:18 test.txt
-rw-r----- 1 kotaprax users  17 Nov 16 15:25 test1.txt

From the abvoe command, we are deriving some columns

>> ls -l | awk '{print $3 "\t" $8 "\t" $9}'
             
kotaprax        12:51   new.txt
kotaprax        12:51   new1.txt
kotaprax        12:57   output.txt
kotaprax        10:18   test.txt
kotaprax        15:25   test1.txt



2) How to print first column from the file using AWK

e.g.,

>> cat test.txt
prabhath kota
lakshmi muvvala
PRABHATH KOTA
LAKSHMI MUVVALA


>>awk '{print $1}' test.txt
(or)
>>awk < test.txt '{ print $1 }'

o/p:
>>cat test.txt
prabhath
lakshmi
PRABHATH
LAKSHMI


3) How to copy the files using AWK

>> ls
a.txt
b.txt
c.txt

It will copy file.txt to file.txt.new for all the txt files

>>ls *.txt | awk '{print "cp "$1" "$1".new"}' | sh

o/p:

>> ls
a.txt
b.txt
c.txt
a.txt.new
b.txt.new
c.txt.new


4) How to list only directories using awk

>>ls
a.txt
b.txt
c.txt
prabhath_test

o/p:

>> ls -l | grep '^d'
#Lists only directories, since directories start with
drwxr-x--- 2 kotaprax users 1024 Nov 23 13:57 prabhath_test


>>ls -l | grep -v '^d' #Lists only files but not directories
-rw-r----- 1 kotaprax users 203 Nov 22 12:51 a.txt
-rw-r----- 1 kotaprax users 282 Nov 23 10:18 b.txt
-rw-r----- 1 kotaprax users  17 Nov 16 15:25 c.txt


5) Remove files using AWK

>>ls
a.txt
b.txt
c.txt
prabhath_test
a.tt
b.tt

>> ls -l *.tt | awk '{print "rm -r "$9}' | sh
#"rm" is a command, in order to execute, "sh" is used

o/p:

>>ls
a.txt
b.txt
c.txt
prabhath_test



6) AWK - Difference between $0 and $1

>> echo "hello1 hello2 hello3" | awk ' {print $0} ' #$0 prints the whole
hello1 hello2 hello3

>> echo "hello1 hello2 hello3" | awk ' {print $3} ' #$1 prints 1st column
hello3



7) How to print 1st column of a file into another file ?

>>cat test.txt
prabhath kota
lakshmi muvvala
PRABHATH KOTA
LAKSHMI MUVVALA

>> awk '{print $1}' test.txt > output.txt

o/p:

>>cat test.txt
prabhath
lakshmi
PRABHATH
LAKSHMI

Unix Grep Examples

Grep
######

1) How to exclude lines in a grep

syntax: grep -v <pattern> <filename>

e.g.,
>> cat test.txt
prabhath
ramesh
vamsi
lakshmi muvvala
PRABHATH
LAKSHMI MUVVALA

>> grep -v "prabhath" test.txt

It will exclude the lines which contain "prabhath"

o/p:
ramesh
vamsi
lakshmi muvvala
PRABHATH
LAKSHMI MUVVALA


2) How to exclude lines in a grep with ignore case

syntax: grep -iv <pattern> <filename>

e.g.,
>> cat test.txt
prabhath
ramesh
vamsi
lakshmi muvvala
PRABHATH
LAKSHMI MUVVALA

>> grep -iv "prabhath" test.txt

It will exclude the lines which contain "prabhath", "Prabhath", "PRABAHTAH" etc.,

o/p:
ramesh
vamsi
lakshmi muvvala
LAKSHMI MUVVALA

3) How to exclude lines which contain multiple patterns at one shot

Syntax: grep -v -e <pattern> -e <pattern> <filename>

e.g.,
>> cat test.txt
prabhath
ramesh
vamsi
lakshmi muvvala
PRABHATH
LAKSHMI MUVVALA


>>grep -v -e "prabhath" -e "lakshmi" test.txt

It will exclude the lines which contains the pattern "prabhath" & pattern "lakshmi"

o/p:
ramesh
vamsi
PRABHATH
LAKSHMI MUVVALA


>>grep -iv -e "prabhath" -e "lakshmi" test.txt

Please note "i" - ignore case
It will exclude the lines which contains the pattern "prabhath", "PRABHATH" & pattern "lakshmi", "LAKSHMI"

o/p:
ramesh
vamsi


4) Counting the number of matches using grep -c

Syntax: grep -c "pattern" filename

e.g.,
>> cat test.txt
prabhath
ramesh
vamsi
lakshmi muvvala
PRABHATH
LAKSHMI MUVVALA

>>grep -c "prabhath" test.txt
1

>>grep -ic "prabhath" test.txt
2


5) Counting the number of lines that does not match the pattern

e.g.,
>> cat test.txt
prabhath
ramesh
vamsi
lakshmi muvvala
PRABHATH
LAKSHMI MUVVALA

>>grep -vc prabhath test.txt
5

(or)

>>grep -v -c prabhath test.txt
5


6) Display N lines around match (Before & After)

Syntax: > grep -C 2 "Pattern" File

e.g.,
>> cat test.txt
prabhath
ramesh
vamsi
lakshmi muvvala
PRABHATH
LAKSHMI MUVVALA


>> grep -C 2 "lakshmi" test.txt

o/p:
ramesh
vamsi
lakshmi muvvala //Actual Match
PRABHATH
LAKSHMI MUVVALA


7) Display N lines Before Match

Syntax: > grep -B 2 "Pattern" File

e.g.,
>> cat test.txt
prabhath
ramesh
vamsi
lakshmi muvvala
PRABHATH
LAKSHMI MUVVALA

>> grep -B 2 "lakshmi" test.txt

o/p:
ramesh
vamsi
lakshmi muvvala //Actual Match


8) Display N lines After Match

Syntax: >> grep -A 2 "Pattern" File

e.g.,
>> cat test.txt
prabhath
ramesh
vamsi
lakshmi muvvala
PRABHATH
LAKSHMI MUVVALA

>> grep -A 2 "lakshmi" test.txt

o/p:
lakshmi muvvala //Actaul Match
PRABHATH
LAKSHMI MUVVALA


9)  Checking for full words, not for sub-strings using grep -w

e.g.,
>> cat test.txt
prabhath
prabhathkota
prabhath kota
ramesh
vamsi
lakshmi muvvala
PRABHATH
PRABHATHKOTA
PRABHATH KOTA
LAKSHMI MUVVALA

Syntax: >> grep -w "Pattern" File

>>grep -iw "kota" test.txt

o/p:
prabhath kota
PRABHATH KOTA


>>grep -i "kota" test.txt

o/p:
prabhathkota
prabhath kota
PRABHATHKOTA
PRABHATH KOTA


10) How to get line numbers in grep

>> cat test.txt
prabhath
prabhathkota
prabhath kota
ramesh
vamsi
lakshmi muvvala
PRABHATH
PRABHATHKOTA
PRABHATH KOTA
LAKSHMI MUVVALA


>> grep -n 'PRABHATH' test.txt

o/p:
7 PRABHATH
8 PRABHATHKOTA
9 PRABHATH KOTA

>> grep -in 'PRABHATH' test.txt

o/p:
1 prabhath
2 prabhathkota
3 prabhath kota
7 PRABHATH
8 PRABHATHKOTA
9 PRABHATH KOTA


11) Grep Pipe Examples

1) Display cpu model name

#With Pipe
]# cat /proc/cpuinfo | grep -i 'Model'

#Without Pipe
]# grep -i 'Model' /proc/cpuinfo    

2) grep dbname *.dbl | grep mysql


12) Some complex examples using Grep...

>> cat test.txt
prabhath
prabhathkota
prabhath kota
ramesh
vamsi
lakshmi muvvala
PRABHATH
PRABHATHKOTA
PRABHATH KOTA
LAKSHMI MUVVALA


>> grep -nC 2 'lakshmi' test.txt

Note: "-C 2" will grep for 2 lines above and 2 lines below
          "-n" will give the line numbers

o/p:
4 ramesh
5 vamsi
6 lakshmi muvvala
7 PRABHATH
8 PRABHATHKOTA


13) Grep OR

1) grep 'pattern1\|pattern2' filename

$ cat employee.txt
100  Thomas  Manager    Sales       $5,000
200  Jason   Developer  Technology  $5,500
300  Raj     Sysadmin   Technology  $7,000
400  Nisha   Manager    Marketing   $9,500
500  Randy   Manager    Sales       $6,000


$ grep 'Tech\|Sales' employee.txt
100  Thomas  Manager    Sales       $5,000
200  Jason   Developer  Technology  $5,500
300  Raj     Sysadmin   Technology  $7,000
500  Randy   Manager    Sales       $6,000

2) grep -E 'pattern1|pattern2' filename

$ grep -E 'Tech|Sales' employee.txt
100  Thomas  Manager    Sales       $5,000
200  Jason   Developer  Technology  $5,500
300  Raj     Sysadmin   Technology  $7,000
500  Randy   Manager    Sales       $6,000


3) egrep 'pattern1|pattern2' filename

$ egrep 'Tech|Sales' employee.txt
100  Thomas  Manager    Sales       $5,000
200  Jason   Developer  Technology  $5,500
300  Raj     Sysadmin   Technology  $7,000
500  Randy   Manager    Sales       $6,000


14) Grep AND

grep -E 'pattern1.*pattern2' filename
grep -E 'pattern1.*pattern2|pattern2.*pattern1' filename

$ grep -E 'Dev.*Tech' employee.txt
200  Jason   Developer  Technology  $5,500

The following example will grep all the lines that contain both “Manager” and “Sales” in it (in any order).
$ grep -E 'Manager.*Sales|Sales.*Manager' employee.txt


15) Grep NOT

grep -v 'pattern1' filename

$ grep -v Sales employee.txt
200  Jason   Developer  Technology  $5,500
300  Raj     Sysadmin   Technology  $7,000
400  Nisha   Manager    Marketing   $9,500

$ egrep 'Manager|Developer' employee.txt | grep -v Sales
200  Jason   Developer  Technology  $5,500
400  Nisha   Manager    Marketing   $9,500


16) Highlighting the search using GREP_OPTIONS

$ export GREP_OPTIONS='--color=auto' GREP_COLOR='100;8'

$ grep this demo_file
this line is the 1st lower case line in this file.
Two lines above this line is empty.
And this is the last line.



17) Show only the matched string

#] grep -o  

$ grep -o "is.*line" demo_file

is line is the 1st lower case line
is line
is is the last line

Mod Perl Notes

mod-perl:
##########
http://www.perl.com/pub/2002/02/26/whatismodperl.html
http://www.perl.com/pub/2002/03/22/modperl.html

Having the Perl interpreter embedded in the server saves the very considerable overhead of starting an external interpreter for any HTTP request that needs to run Perl code.

At least as important is code caching: the modules and scripts are loaded and compiled only once, when the server is first started. Then for the rest of the server's life the scripts are served from the cache, so the server only has to run the pre-compiled code. In many cases, this is as fast as running compiled C programs.

The primary advantages of mod_perl are power and speed

You have full access to the inner workings of the Web server and you can intervene at any stage of HTTP request processing

There are big savings in startup and compilation times.


Difference between Apache::Registry, Apache::PerlRun ?
################################################################

Speed Wise :
Apache::Registry > Apache::PerlRun > Perl CGI

The Apache::PerlRun Class
###########################

The Apache::PerlRun handler is intended for Perl CGI scripts that depend strongly on the traditional
one-process-per-execution CGI model and cannot deal with being invoked repeatedly in the same process.

For example,
a script that depends on a lot of global variables being uninitialized when it starts up is unlikely to work properly under Apache::Registry.

Like Apache::Registry, Apache::PerlRun manages a directory of CGI scripts, launching them when they are requested.
However, unlike Apache::Registry, Apache::PerlRun module does not cache compiled scripts between runs. A script is loaded and compiled freshly each time it is requested.

However, Apache::PerlRun still avoids the overhead of starting a new Perl interpreter for each CGI script,
so it's faster than traditional Perl CGI scripting but slower than Apache::Registry or vanilla Apache API modules.

It offers a possible upgrade path for CGI scripts: move the script to Apache::PerlRun initially to get a modest performance bump.
This gives you time to rework the script to make it globally clean so that it can run under Apache::Registry for the full performance benefit.

The configuration section for running Apache::PerlRun is similar to Apache::Registry:

Alias /perl-run/ /home/www/perl-run/
<Location /perl>
 SetHandler     perl-script
 PerlHandler    Apache::PerlRun
 Options        +ExecCGI
 # optional
 PerlSendHeader On
</Location>

The Apache::PerlRun handler is only a small part of the picture. The rest of the Apache::PerlRun class provides subclassable methods that implement the functionality of Apache::Registry.

The Apache::PerlRun handler simply uses a subset of these methods; other modules may override certain methods to implement the Apache::Registry enviroment with a few twists. However, these Apache::PerlRun class methods were not fully defined when this book was going to press.


The Apache::Registry Class
##############################

The Apache::Registry class is essentially a CGI environment emulator that allows many CGI scripts to run without modification under mod_perl. Because there are many differences between CGI and the Apache API, Apache::Registry has to do a great deal of work to accomplish this sleight of hand.

It loads the scripts in its designated directory, compiles them, and stores them persistently in a memory structure. Before Apache::Registry runs a script, mod_perl will set up the various CGI environment variables, provided PerlSetupEnv is configured to On, which is the default.

When the PerlSendHeader directive is On, mod_perl monitors the text printed by the script, intercepts the HTTP header, and passes it through send_cgi_header(). It also arranges for STDIN to be read from the request object when the script attempts to process POST data.

Apache::Registry also monitors the modification dates of the script files it is responsible for and reloads them if their timestamp indicates they have been changed more recently than when they were last compiled.

Despite its complexity, Apache::Registry is easy to set up. The standard configuration consists of an Alias directive and a <Location> section:

Alias /perl/ /home/www/perl
<Location /perl>
 SetHandler     perl-script
 PerlHandler    Apache::Registry
 Options        +ExecCGI
 # optional
 PerlSendHeader On
</Location>

After restarting the server, you can place any (well, almost any) Perl CGI script into /home/www/perl (or the location of your choice) and make it executable. It runs just like an ordinary CGI script but will load much faster. The behavior of Apache::Registry can be tuned with the following directives:

PerlTaintCheck
    When set to On, mod_perl will activate Perl taint checks on all the scripts under its control. Taint checks cause Perl to die with a fatal error if unchecked user-provided data (such as the values of CGI variables) is passed to a potentially dangerous function, such as exec(), eval(), or system().

PerlSendHeader
    When set to On, mod_perl will scan for script output that looks like an HTTP header and automatically call send_http_header(). Scripts that send header information using CGI. pm's header() function do not need to activate PerlSendHeader. While scripts that use CGI.pm's header() will still function properly with PerlSendHeader On, turning it Off will save a few CPU cycles.

PerlFreshRestart
    If PerlFreshRestart is set to On, mod_perl will flush its cache and reload all scripts when the server is restarted. This is very useful during module development to immediately see the changes to the source code take effect.

PerlWarn
    If the script mentions the -w switch on its #! line, Apache::Registry will turn Perl warnings on by setting the $^W global to a nonzero value. The Perl-Warn directive can be configured to On to turn on warnings for all code inside the server.

Apache::Registry has several debug levels which write various informational messages to the server error log.

Apache::Registry scripts can change the debug level by importing Apache::Debug with its level pragma:

 use Apache::Debug level => $level;

The debug level is a bit mask generated by ORing together some combination of the following values:

1     Make a note in the error log whenever the module is recompiled
2     Call Apache::Debug::dump() on errors
4     Turn on verbose tracing

The current value of the debug level can be found in the package global $Apache::Registry::Debug. You should not set this value directly, however. See Chapter 2, A First Module, for more hints on debugging Apache::Registry scripts.

===============================================================================================================

MySQL/Oracle Database Examples

How to find Difference b/w dates
####################################
select WSM_RMS_MSISDN_TYPE, COUNT(*) from WSM_REMINDER_SERVICE_LOG where
WSM_RMS_SEND_DT >= to_date('30-11-2008 00:00:00','DD-MM-YYYY HH24:MI:SS') and
WSM_RMS_SEND_DT <= to_date('02-12-2008 23:59:59','DD-MM-YYYY HH24:MI:SS') group by WSM_RMS_MSISDN_TYPE;

SQL> create table datemath (start_date date,end_date date);
SQL> insert into datemath (start_date,end_date)
values ( to_date('01-OCT-2006 13:00:00', 'DD-MON-YYYY HH24:MI:SS'), to_date('01-OCT-2006 14:00:00','DD-MON-YYYY HH24:MI:SS') );
SQL> commit;

SQL> select to_char(start_date,'DD-MON-YYYY HH24:MI:SS') START_DATE ,to_char(end_date,'DD-MON-YYYY HH24:MI:SS') END_DATE
     from datemath;
START_DATE END_DATE
-------------------- --------------------
01-OCT-2006 13:00:00 01-OCT-2006 14:00:00


SQL> select to_char(start_date,'DD-MON-YYYY HH24:MI:SS') START_DATE ,to_char(end_date,'DD-MON-YYYY HH24:MI:SS') END_DATE
from datemath;

START_DATE END_DATE
-------------------- --------------------
01-OCT-2006 13:10:00 10-OCT-2006 14:00:00


****************************************************************************************************************
SQL> select to_char( start_date, 'dd-mon-yyyy hh24:mi:ss' ) start_date,
2 trunc( end_date-start_date ) days,
3 trunc( mod( (end_date-start_date)*24, 24 ) ) hours,
4 trunc( mod( (end_date-start_date)*24*60, 60 ) ) Minutes,
5 trunc( mod( (end_date-start_date)*24*60*60, 60 ) ) Seconds,
6 to_char( end_date, 'dd-mon-yyyy hh24:mi:ss' ) end_date
7* from datemath;

START_DATE           Days  HOURS  MINUTES   SECONDS END_DATE
-------------------- ----- -----  --------  ------  ----------
01-oct-2006 13:10:00 9     0      50        0       10-oct-2006 14:00:00
****************************************************************************************************************

sql> select end_date - start_date from datemath;
END_DATE - START_DATE
-------------------
.041666667

SQL> select (end_date-start_date)*24 hours from datemath;
HOURS
----------
1

Multiply by 24 and again by 60 to get the number of minutes

SQL> select (end_date-start_date)*24*60 minutes from datemath;
MINUTES
----------
60

Multiply by 24 and again by 60 and again by 60 to get the number of seconds

SQL> select (end_date-start_date)*24*60*60 seconds from datemath;
SECONDS
----------
3600


MySQL/Oracle Statements
##########################

Select * from eng_traslate where PROG_ID = '9041' and rownum > 0 and rownum <=2;

select * from (select WSM_RMS_MSISDN, COUNT(*) from WSM_REMINDER_SERVICE_LOG
                where WSM_RMS_SEND_DT >= to_date('30-11-2008 00:00:00','DD-MM-YYYY HH24:MI:SS') and
                      WSM_RMS_SEND_DT <= to_date('02-12-2008 23:59:59','DD-MM-YYYY HH24:MI:SS')
                group by WSM_RMS_MSISDN
              )
where ROWNUM >0 and ROWNUM <= 2; 


select WSM_RMS_MSISDN_TYPE as op_type, WSM_RMS_STATUS as status, COUNT(*) as CNT
from WSM_REMINDER_SERVICE_LOG
where WSM_RMS_SEND_DT >= to_date('30-11-2008 00:00:00','DD-MM-YYYY HH24:MI:SS') and
      WSM_RMS_SEND_DT <=  to_date('02-12-2008 23:59:59','DD-MM-YYYY HH24:MI:SS')
group by WSM_RMS_MSISDN_TYPE, WSM_RMS_STATUS
order by op_type;


sql> CREATE TABLE DATETEST(DATECOL DATE);
sql> INSERT INTO DATETEST(DATECOL) VALUES (TO_DATE('01-JAN-2006 08:18:23','DD-MON-YYYY HH24:MI:SS'));
sql> commit;

- The default dispaly of DATE column is 'DD-MON-YY'
- U can change the format of the default dispaly of DATE easily.

SQL> select datecol from datetest;
DATECOL
---------
01-JAN-06

SQL> alter session set nls_date_format='DD/MON/YYYY';
Session altered.

SQL> select datecol from datetest;
DATECOL
-----------
01/JAN/2006



SQL> create or replace view text2date as select to_date('05-JAN-2006','DD-MON-YY') text2date111 from dual;
View created.

SQL> desc text2date
Name Null? Type
-----------------
TEXT2DATE111 DATE


SQL> select text2date111 from text2date;
TEXT2DATE111
------------
05-JAN-06

SQL> select to_char(text2date,'Day') text2date from text2date;
TEXT2DATE111
-------------
Thursday


Enum:
#######
CREATE TABLE employee_person (
    id int unsigned not null primary key,
    address varchar(60),
    phone int,
    email varchar(60),
    birthday DATE,
    sex ENUM('M', 'F'),
    m_status ENUM('Y','N'),
    s_name varchar(40),
    children int
);

Grant Previliges
#####################

create database atmail123;                                              

mysql> grant all on atmail123.* to root@112.118.61.125 identified by 'mp0d';
mysql> grant all on atmail123.* to webmail@112.119.600.115 identified by 'webmail';
mysql> grant all on atmail123.* to root@114.135.61.102 identified by 'mp0d';