Extract specific values from a file using shell script

Question

How can I extract values from a file using shell-script (grep, awk or sed for example). I have the following structure (described below) and I want to get an output file with only the second column of the file. I tried using grep: grep -oP '\s*U238\s*\*\s+[-+]?[0-9]*\.?[0-9]+([eE][-+]?[0-9]+)?' file >U238_out to extract all U238 values from the entire file and store it in an output file (U238_out).With this I get the following output:

 U238     *  1.779265E+03
 U238     *  5.418484E-03
 U238     *  1.777156E+03
         ...

but I want to obtain this structure:

1.779265E+03
5.418484E-03
1.777156E+03

File Structure:

  PERIODICITY : 0
  SYMMETRY    : 0


  MATERIAL MFUEL   
  MEDIUM   MFUEL    VOLUME  8.308106E+05


  *******************************************************
  * ISOTOPE  *   MASS (KG)   *   CIP    *    EQFMASS    *
  *******************************************************
  * U238     *  1.779265E+03 *   28.125 *  0.000000E+00 *

Thanks in advance.

Welcome to SO, please do add your efforts which you have put in order to solve your own problem; also do add expected output too in your post and let us know then. — RavinderSingh13
– RavinderSingh13, Commented May 30, 2019 at 6:19
Thanks for the reply, but the whole file has a more complex structure with respect to the attached. — Yro
– Yro, Commented May 30, 2019 at 6:49

Jotne · Accepted Answer · 2019-05-30 08:10:41Z

2

You can use:

awk '$2=="U238" {print $4}' file > U238_out

or

awk '$2~/^U238$/ {print $4} file > U238_out

If U238 in 2nd field, print 4th field:

1.779265E+03

edited May 30, 2019 at 8:10

answered May 30, 2019 at 6:46

Jotne

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2 Comments

Yro Over a year ago

Thanks for your help, this code worked: awk '$2~/^U238$/ {print $4}' file >output

Jotne Over a year ago

@yro both should work. If you like it, accept it. :)

UtLox · Accepted Answer · 2019-05-30 06:50:01Z

0

you mean something like this?

sed '/\s*\*/!d;s/\s*[*][^*]*[*]\s*\([-+.E0-9]*\).*/\1/;/^$/d' file.txt

explanation

/\s*\*/!d          # delete line not started with [blank]*
;                  # separator for next sed command
s/                 # substitute
\s*                # ignore leading blanks
[*]                # search first *
[^*]*[*]           # ignore everything until the next *
\s*                # ignore blanks
\([-+.E0-9]*\)     # save number into arg1 (\1)
.*                 # ignore rest of line
/\1/               # print only arg1
;                  # separator for next sed command
/^$/d              # ignore empty lines (first 3)

output

3.099319E+02
1.274088E+01
1.779265E+03
3.789596E+02
1.760032E+02
5.049642E+01
5.002164E+01
4.777184E+00
2.594883E-19
2.594883E-19

answered May 30, 2019 at 6:50

UtLox

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1 Comment

Yro Over a year ago

Thanks everyone for your help!

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