Awk from different lines

awkgreptext processing

I am trying to extract some data from a file that is constantly updating and I have figured out how to filter two strings with grep. The output is as follows:

!    total energy              =   -9744.24963670 Ry
     convergence has been achieved in 188 iterations
!    total energy              =   -9744.30001681 Ry
     convergence has been achieved in 140 iterations
!    total energy              =   -9744.33953891 Ry
     convergence has been achieved in 155 iterations
!    total energy              =   -9744.36584201 Ry
     convergence has been achieved in 164 iterations
!    total energy              =   -9744.37925372 Ry
     convergence has been achieved in 154 iterations
!    total energy              =   -9744.39185493 Ry
     convergence has been achieved in 153 iterations
!    total energy              =   -9744.39836617 Ry
     convergence has been achieved in 160 iterations

Now what I would like to do is to extract from these lines the numbers as follows:
from the line starting with ! I want the number in column no 5 and from the next line in the grep output I want the number in column no 6.
Next I would like these numbers written in a separate file as two separated columns as:

188 -9744.24963670
140 -9744.30001681
155 -9744.33953891
164 -9744.36584201

I was thinking that an approach with awk by looping through all these grep results and then looking at odd numbered lines and print column 5 and then for even lines print column 6. But I have no idea how to do this.

I have tried extracting individual results into variables separately:

var1=$(grep '!' input.file | awk '{print $5}')

and

var2=$(grep 'convergence has been achieved' input.file | awk '{print $6}')

and then I tried to write them to a file as:

echo $var1 $var2 > data.dat

However the result is not as expected:

188                                                                                                                                                                                             
140
155
164
154
153
160 -9744.24963670
-9744.30001681
-9744.33953891
-9744.36584201
-9744.37925372
-9744.39185493
-9744.39836617

I don't know how to write them in the form I mentioned above. Also since the file is constantly updated I imagine the piece of code to be combined with a while loop until and end condition (I know how to do this last part)

I hope I explained this clearly!

Best Answer

awk solution:

awk 'v && NR==n{ print $6,v > "result.txt" }/^!/{ v=$5; n=NR+1 }' file

  • <condition1> { <statement> ... }<condition2>{ <statement> ... } - conditions with respective statements will be evaluated consecutively

  • /^!/{ v=$5; n=NR+1 } - on encountering line starting with ! - capture the 5th field value $5 and plan the next line number NR+1 (assigning to variable n)

  • v && NR==n - if we have the 1st crucial number v and the current record number NR is the needed "next line number" n - print the values into file result.txt

The result.txt file contents:

188 -9744.24963670
140 -9744.30001681
155 -9744.33953891
164 -9744.36584201
154 -9744.37925372
153 -9744.39185493
160 -9744.39836617
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