Score:0

Ubuntu

How to add two integer values in Linux?

hariraj

1/13/23, 1:27 PM

#!/bin/bash

cd /pg
file=`ls -l |awk '{print $9}'`
list=()
for i in $file
do
  echo $i
  a=`cat /pg/$i | head  -n  1 |awk '{print $8}'`
  b=`cat /pg/$i | head  -n  2 |awk '{print $8}'`
  #a1=`echo "$a" | tr -d  '"'`
  #b1=`echo "$b" | tr -d  '"'`
  echo $a
  echo $b
  c="$(($a+$b))"
  list=($c)
  #a1=`cat /pg/$i | head -n 2 |awk '{print $8}'`
done

While executing the above code i'm getting the below error please help me to fix the issue output of the values is a=30 and b=30 but still not able to add both.

/bin/max_timetrack.sh: line 16: 30+30
30: syntax error in expression (error token is "30")

0 + 0

apt

bash

Score:5

Ubuntu

pLumo

1/13/23, 1:35 PM

You're error is in this line:

b=`cat /pg/$i | head  -n  2 |awk '{print $8}'`

head won't give you the second line, but the n first lines.
So b will actually be:

30
30

and not 30 how you said. Hence the error,

30+30
30

You would need (while keeping your complicated structure):

b=`cat /pg/$i | head  -n  2 |awk '{print $8}' | tail -n 1`

However!

There is a lot of useless/strange use of things in your little script:

This would be enough:

b=$(awk 'NR==2{print $8}' "/pg/$i")

Note the use of $(...) instead of backticks, which is the same but to be preferred.

Same with this line

a=`cat /pg/$i | head  -n  1 |awk '{print $8}'`

would better be

a=$(awk 'NR==1{print $8}' "/pg/$i")

Anyways, you can do the arithmetic inside awk only:

c=$(awk 'NR<=2{sum+=$8}END{print sum}')

Also you're parsing ls, which is a bad choice:

file=`ls -l | awk '{print $9}'`

Can't you just do this?

for i in *; do ... done

Depending on what you want to do with c, you can probably write the whole script as one awk command.

0 + 0

hariraj

1/14/23, 6:31 AM

Thanks Mr.PLumo the above answer is working for me.