Searching using grep

gregarion · 01-14-2010, 05:58 AM

okay, i seem to have a problem with the search command which i used.

Code:

echo -n "Title:"
read Title  
echo -n "Author:"
read Author
price_check=`grep $Title fruit | grep $Author | awk -F":" '
if [ "$price_check"="$Author" ] ; then
  echo "book exist"
else
 echo " Book does not exist"
fi
{print $3}'

`

Code:

Persia:42:John      ---database
France:50:Mabel 
Persia:50:Rach
Germany:60:John

for example, the user is to input title as "Persia" and "Author" as John. i will then use grep to search for lines which contain the title, then pipe it into another grep command which will then search for author based on the row available, then after that print $3 right?

but for some reason, when i did a check on it, it does not seem to work. when i input data which is not in the database, it still displays the message "book exist" instead of telling me "book does not exist".

What is the correct format or coding to be used to do a search based on two inputs?

SeymourButts · 01-14-2010, 06:24 AM

Did you try dropping the dbl quotes?

Code:

if [[ $price_check = $Author ]] ; then

gregarion · 01-14-2010, 07:12 AM

did not help. still the same result.

SeymourButts · 01-14-2010, 07:20 AM

You may also want to look at this line closely. The punctuation marks don't match up. In front of grep you have an acute, while at the end of the line you have a single quote.

Code:

price_check=`grep $Title fruit | grep $Author | awk -F":" '

And, what exactly is "fruit".

gregarion · 01-14-2010, 07:27 AM

i tried using the if statement :

Code:

awk  '{if ($1==$Title && $3==$Author) print $3 } ' fruit

but there does not seem to be working. am i using the "if" statement wrongly?

gregarion · 01-14-2010, 07:44 AM

Sorry, fruit is the name of my database. and for the single quote, let me correct it. the code looks like this :

Code:

price_check=`grep $Title fruit | grep $Author | awk -F":" '

pixellany · 01-14-2010, 07:55 AM

I don't see that you changed it---it should be backtics at both ends..

BUT: This syntax is obsolete---the current advice is to do it this way:

Code:

price_check=$(grep $Title fruit | grep $Author | awk -F":")

For your question about the if statement: AWK syntax is:
pattern {action}
so it looks like you have "{" in the wrong place.

gregarion · 01-14-2010, 08:25 AM

Code:

echo -n "Title:"
read Title  
echo -n "Author:"
read Author

price_check=$(grep $Title fruit | grep $Author | awk -F":"'{print $2}')

echo $price_check

Okay, am i correct to say that there should be a print $3 there as it is where the Author columm is? so basically, this is suppose to check for line which contain $title , then with that info, check for lines which contain $Author , and then with the row which we have , print out $2 which should be the price. the echo command will then show the price as an output right?

that is what i did, but nothing seems to be working.

could you show me an example how the if statement should be used. i tried out changing the location of the { from :

Code:

price_check=`awk  -F: '{if ($1=='$Title' && $3=='$Author') print $3 } ' fruit`

to

Code:

price_check=`awk  -F: 'if ($1=='$Title' && $3=='$Author') { print $3 } ' fruit`

but it does not seem to work.

pixellany · 01-14-2010, 08:53 AM

I can't relate your first question to the preceding discussion,

In the "price_check" statement, why do you have quotes on $Title and $Author? I think the resulting test would be--e.g.: Does the value of variable 3 equate to the literal string "$Author"

gregarion · 01-14-2010, 09:00 AM

yes, that what i am trying to achieve. im trying to do a test to check if we are going to delete the information on the right row. i guess the best way to do it would be to run pull out a data from the row which you have specified and then compare it to the user input.

Do you know of any other ways in which i do this search?

pixellany · 01-14-2010, 09:10 AM

Sorry---I am not connecting your answers with my questions....

Are you trying to compare the value of variable "3" with the literal string "$Author"? I don't think so---I think you want the value of the variable named "Author".

If I'm correct, then you want--e.g.: if ($3==$Author)