Extracting value from a flat file using shell script

Question

I'm trying to extract the value present between brackets in the last row of a flat file e.g. " last_line (4) ". This is the last line and I want to extract 4 and store it in a variable. I have extracted the last row using tail command but now I am unable to extract the value between the brackets.

Kindly help.

try `| grep -Eo '$.*$'` and if you want to remove the brackets you can add a `| grep -Eo '[[:alnum:]]*'` at the end. — Klaus, Aug 12 '15 at 07:52
Is last row always contains numeric value ? if yes then simply use `grep -o '[0-9]*'` — Kiran Choudhary, Aug 12 '15 at 07:52

score 1 · Answer 1 · answered Aug 12 '15 at 07:56

1

Using awk:

$ cat input
first line
2nd line
last line (4) with some data

$ awk -F'[()]' 'END{print $2}' input
4

answered Aug 12 '15 at 07:56

Fredrik Pihl

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Right approach so `+1` but the last record read is only saved in the `END` section in some awks, to be portable you need to use `awk -F'[()]' '{s=$2} END{print s}' input`. – Ed Morton Aug 12 '15 at 17:03

score 1 · Answer 2 · answered Aug 12 '15 at 08:38

l=$(tail -n1 filename); tmp=${l##*(}; tmp=${tmp%)*}; printf "tmp: %s\n" $tmp

Output

tmp: 4

Written in script format, you are using substring removal to trim everything up to the first ( and everything after the last ) from the last line, leaving only 4:

l=$(tail -n1 filename)    ## get the last line
tmp=${l##*(}              ## trim to ( from left
tmp=${tmp%)*}             ## trim to ) from right
printf "tmp: %s\n" $tmp

score 0 · Answer 3 · answered Aug 12 '15 at 08:25

0

sed:

sed -n '${s/.*(//;s/).*//;p}' file

answered Aug 12 '15 at 08:25

Kent

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score 0 · Answer 4 · edited Aug 12 '15 at 10:05

0

U can use this script.

In this script i saved the last line in a tmp file and at last removed it. the number between the brackets() is in variable WORD

 #!/bin/ksh

if test "${DEBUG}" = "Y"
then

   set -vx

fi

tail -1 input>>tmp


WORD=`sed -n 's/.*(//;s/).*//;p' tmp`

echo $WORD

rm tmp

edited Aug 12 '15 at 10:05

Ashish Kakkad

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answered Aug 12 '15 at 09:56

Grv

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Extracting value from a flat file using shell script

4 Answers4