summing values of variables in bash

Question

I'm trying to get all the regular files opened by all the processes in the current session. I have this code

while read pid
do

        FILES_ACTUAL=$(lsof -p $pid | grep REG | wc -l)   


done < <(ps -o pid,tt -u $USER | grep $CURRENT_TERMINAL | awk '{print $1}')

echo $FILES_ACTUAL

but I don't know how to add up, inside the while, the variable $FILES_ACTUAL.. I tried to use the awk command, but I couldn´t do it.

phininity · Accepted Answer · 2012-10-10 12:53:31Z

1

You can perform bash arithmetic by enclosing the statements inside (()):

NEW_FILES=$(lsof -p $pid | grep REG | wc -l)
((FILES_ACTUAL+=NEW_FILES))

edited Oct 10, 2012 at 12:53

answered Oct 10, 2012 at 12:34

phininity

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nsa · Accepted Answer · 2018-11-06 18:26:22Z

0

There is also a comand called expr which does simple arithmetic operations with integers and can be used like this:

expr $VAR1 + $VAR2

answered Nov 6, 2018 at 18:26

nsa

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