To read a particular line in a txt file and decision making

bal_nair1 · 03-25-2013, 04:11 AM

Hi all,

I am new to Linux programming,and I am supposed to make a script which runs as shown below

We have a txt file

say abc.txt

with the following content
$23456781234567812345678123456781234567812345678
PSHELL x y z w s
where x,y,z,w and s are some numerical values.

The script should read the txt file and go to the line containing the word PSHELL and check for all the eight-field spaces in the line, whether a particular number is wriiten in a field .

for example script should check whther the value of x ,y, z,w or s is zero.it it is zero it should write in a seperate txt file.

Hope you understand the problem.

Thank you in advance

pan64 · 03-25-2013, 04:53 AM

I do not really understand it, but it looks like a homework.
I would use awk or perl, that would be easy. What do you prefer? What have you tried?

bal_nair1 · 03-25-2013, 06:58 AM

Sorry it needs more explanation
123456781234567812345678123456781234567812345678
PSHEll 1 4 23 4 0

Now I want script to check any 0 value is present in the line Pshells, but forevery 8 chara field

In this case zero is present in the 6th field

Hope u got

danielbmartin · 03-25-2013, 07:14 AM

Help us to help you. Provide a sample input file (10-15 lines will do). Construct a sample output file which corresponds to your sample input and post both samples here. With "Before and After" examples we can better understand your needs and also judge if our proposed solution fills those needs.

Daniel B. Martin

colucix · 03-25-2013, 07:41 AM

@bal_nair1: it would have been more clear if you used CODE tags to embed data or lines of code. I interpret your input as

Code:


123456781234567812345678123456781234567812345678
PSHELL  1       4       23      4       0

where the line in grey is just a meter to check the position. Moreover, it looks like the fields are separated by TAB (not blank spaces), is this correct?

More information is required and specifically:
. you are going to write a script... in which language?
. is this homework, as someone suggested?
. what have you tried so far and where did you stick?
Please help us to help you.

theNbomr · 03-25-2013, 09:22 AM

Is this something like what you're trying to accomplish?

Code:

read PSHELL x y z w s < <(grep PSHELL abc.txt)

if [[ $x = 0 ]]; then echo zero; else echo nonzero; fi

if [[ $y = 0 ]]; then echo zero; else echo nonzero; fi

if [[ $z = 0 ]]; then echo zero; else echo nonzero; fi

if [[ $w = 0 ]]; then echo zero; else echo nonzero; fi

if [[ $s = 0 ]]; then echo zero; else echo nonzero; fi

--- rod.

bal_nair1 · 04-04-2013, 07:26 AM

I would be explaining it again, I am happy dat with my bad explaination all of you could manage to understand it

a b c d e f
123456781234567812345678123456781234567812345678
PSHELL 1 4 23 4 0

the script should read the line contains PSHELL , and while checking each field of the line, the script returns the value under the each field

say in this case

a = 1
b = 4
c = 23
d = 4
e = 0
for it should return no values are assigned

The task is self assigned one.

Thank you in advance.

TB0ne · 04-04-2013, 09:32 AM

Quote:

Originally Posted by bal_nair1

I would be explaining it again, I am happy dat with my bad explaination all of you could manage to understand it

Code:

            a     b       c       d     e    f
123456781234567812345678123456781234567812345678
PSHELL  1       4       23       4       0

the script should read the line contains PSHELL , and while checking each field of the line, the script returns the value under the each field say in this case

Code:

a = 1
b = 4
c = 23
d = 4
e = 0

for it should return no values are assigned The task is self assigned one.

Ok...so again, post what you've written/done/tried, and some more of the input file, and we can try to help, but we're not going to write the script for you. If you want a hint on how to do it, I'd read both lines into different variables, then just read the positions of what you like and output them.

redfox2807 · 04-04-2013, 02:44 PM

Well, didn't you specify the language you need or did I miss something?

Code:

1. read file line by line
2. find the line that contains/starts with (depending on the input file possible variations) PSHELL
3. assign the line value to a string variable
4. split the string by spaces and/or tab character and assign the resulting values to an array-like object. Depending on the language chosen this might need string to int conversion
5. process the array items however you like

the above is written with Qt/C++ in mind. Many of scripting lanquages are designed to do several steps of this algorithm at once.