Question

The problem is like this:

There is a script called run, I need to change the operation of run to make the 2nd field of the output of run to be 0 (Please note: it’s not the output of run but a part of it). I just don’t know how to judge the value of the the 2nd field of the output of run for a loop.

Does anyone have any good ideas? Thank you.

Answer 1

See this snippet :

out=$(command | awk '{print $2}')
((out)) || echo "zero detected"

or simply:

command | awk '($2 == 0) {print "zero detected"}'

On in a for loop :

command | while read a b c d; do
    ((b)) || echo "zero detected"
done

note:
((...)) is an arithmetic command, which returns an exit status of 0 if the expression is nonzero, or 1 if the expression is zero. Also used as a synonym for “let”, if side effects (assignments) are needed. See http://mywiki.wooledge.org/ArithmeticExpression