Linux Shell - How to assign a variable to a binary expression?

Question

I have the following code:

TEMP1=$(awk '$12 == "beacon_server" {print}' < numbers2.log | awk -v var="$i" '{total += $var} EN    D {print total/NR}')

Almost the same for the other TEMP-variables.

Now i want to calculate the following and save it in a new variable RESULT:

RESULT=$(expr 100 - $TEMP1 - $TEMP2 - $TEMP3 - $TEMP4)

The error message is telling me that there is a non-integer argument --> expr: non-integer argument

How can I resolve this error?

Well, what are the values of each of the `TEMP` variables when you get that error? One or more of them *isn't* an integer. As an aside, prefer `RESULT=$(( 100 - $TEMP1 - $TEMP2 - $TEMP3 - $TEMP4))` to using the external command `expr`. — chepner, May 23 '17 at 14:45
@CharlesDuffy: I mean the multiple subtractions with binary expression (maybe it should be called binary expressionS) — manuelgr, May 23 '17 at 14:50
@chepner: The TEMP variables are real numbers. If I do it without the expr as you said, I get this: `arithmetic expression: expecting EOF: " 100 - 1 - 2.23333 - 0.333333 - 0"` — manuelgr, May 23 '17 at 14:54
@ErebosM, what binary expressions? `-` is not a binary expression, in the "bitwise" sense of the word (indeed, bitwise math doesn't generally make much sense with floating-point math). — Charles Duffy, May 23 '17 at 15:01
@ErebosM, ...and inasmuch as you're trying to do non-integer math, the flagged duplicates are entirely apropos. — Charles Duffy, May 23 '17 at 15:02

Nahuel Fouilleul · Accepted Answer · 2017-05-23T14:57:16.063

1

Error message means that one of the arguments is not an integer to find which and to fix the problem you have to display variables content as the file numbers2.log is not provided we can't find the values.

echo variable

echo "TEMP1=$TEMP1"
...

Or

declare -p ${!TEMP*}

To compute floating point numbers values

exit | awk "END{ print 100 - $TEMP1 - $TEMP2 - $TEMP3 - $TEMP4 }"

or

bc -l <<<"100 - $TEMP1 - $TEMP2 - $TEMP3 - $TEMP4"

edited May 23 '17 at 14:57

answered May 23 '17 at 14:39

Nahuel Fouilleul

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The problem is not indirect expansion, but using floating point numbers with `expr` (notice the `print total/NR` in the awk command). – Benjamin W. May 23 '17 at 14:42
How would this result in a problem? Or moreover how can I solve it with still using floating points? – manuelgr May 23 '17 at 14:49
`expr` command is limited can only compute integers – Nahuel Fouilleul May 23 '17 at 14:57
@NahuelFouilleul : The one with `exit` worked for me. Can you please tell me why you pipe `exit` into the `awk` function? What does the whole line do? – manuelgr May 23 '17 at 15:00
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`exit | ` is to close input redirection for awk `awk '...' < /dev/null` works also – Nahuel Fouilleul May 23 '17 at 15:01
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Why not just use ` – Charles Duffy May 23 '17 at 15:03
Initially I was using `<&-` but it's not working with my current version of bash (4.2) whereas following man bash should close the the input, I remembered the `exit|` semantic which I already seen before, comparing `strace -f bash -c 'command'` there's an overhead – Nahuel Fouilleul May 23 '17 at 15:22

Linux Shell - How to assign a variable to a binary expression?

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