Expression not getting evaluated in shell script

Question

TEST1=`echo $QUERY_DAYS3 | awk '{print $1}'`
echo $TEST1

TEST2=`echo $QUERY_DAYS3 | awk '{print $2}'`
echo $TEST2

mailx -s "Data Report" -r [email protected] [email protected] <<EOF

Error Percentage: $((100 * ($TEST2/ $TEST1)))

EOF

In my bash Shell script I have the above code from which I am sending email. But when I check my email I always see Error Percentage written like as it is written in my above code. It is not evaluating the multiplication and division expression.

I am running the above script like this-

sh -x test1.sh

In the email I get like this-

Error  Percentage: $((100 * (183563 / 3793277)))

I am running SunOS.

May be I need to use Back-Ticks here?

Update:-

My updated script that I am using currently-

TEST1=`echo $QUERY_DAYS3 | awk '{print $1}'`
echo $TEST1

TEST2=`echo $QUERY_DAYS3 | awk '{print $2}'`
echo $TEST2

mailx -s "Data Report" -r [email protected] [email protected] <<EOF

Error Percentage: $(( 100 * $TEST2 ) / $TEST1)

EOF

I am running it like this below-

sh -c 'exec ./test.sh'

After trying the suggestion given by lot of peoples. I am getting this error-

./test.sh: command substitution: line 176: syntax error near unexpected token `/'
./test.sh: command substitution: line 176: `( 100 * $TEST2 ) / $TEST1'

What wrong I am doing now? Any thoughts?

Update:-

After making changes, it start working-

Mismatch  Percentage: $((( 100 * $TEST2 ) / $TEST1))

But in the email, the percentage I get was rounded to only one figure like 4 only instead of showing as 4.34563235 How can I get full numbers instead of getting rounded off to one digit.?

I couldn't reproduce your problem, but you might want to use ( 100 * $TEST2 ) / $TEST1 in there, otherwise you'll always get a percentage rounded to zero. — martin clayton
– martin clayton, Commented Oct 2, 2012 at 21:22
Are you certain bash is used as the shell? What does echo $SHELL give? — usta
– usta, Commented Oct 2, 2012 at 21:27
@usta, agreed, doesn't appear that bash is being used. Ran his script under bash and sh under SunOS, works as expected under bash — iruvar
– iruvar, Commented Oct 2, 2012 at 21:32
IIRC, Solaris's /bin/sh is Bourne shell, not bash, at least up to Solaris 10... — twalberg
– twalberg, Commented Oct 2, 2012 at 21:50

sehe · Accepted Answer · 2012-10-03 00:31:17Z

1

You can't expect it to run under bash, if you explicitely tell sh to execute it... Try

bash -x test1.sh

Having

#!/bin/bash

as the first line, will only work if you directly execute the script:

./test1.sh

It needs to be 'executable' for that to work

chmod +x test1.sh

Update

Error Percentage: $(( 100 * $TEST2 ) / $TEST1)

needs to be

Error Percentage: $((( 100 * $TEST2 ) / $TEST1))

edited Oct 3, 2012 at 0:31

answered Oct 2, 2012 at 21:41

sehe

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4 Comments

arsenal Over a year ago

If I need to explicitly tell sh to execute it, then is there any way I can run this by using sh? May be using back-ticks?

arsenal Over a year ago

I tried your suggestion. And I am getting an error. I have updated my question. Any thoughts why is it happening?

sehe Over a year ago

@user1419563 yeah, too few parentheses. I've updated my answer

arsenal Over a year ago

Thanks it worked. But I have one final question that I have updated in my question. My result is getting rounded off instead of showing full numbers.

usta · Accepted Answer · 2012-10-03 08:43:09Z

0

Make sure that the script indeed runs with bash. The standard way to do it is to have this as the first line in your script:

#!/usr/bin/env bash

Don't have any experience with SunOS though, so not sure if that will work there or will need some slight modification.

Edit: now that it runs with bash, looks like you need it to be:

Error Percentage: $(( ( 100 * $TEST2 ) / $TEST1 ))

Update: bash does integer arithmetic only. For floating-point arithmetic you can do

Error Percentage: `echo "scale=8; ( 100 * $TEST2 ) / $TEST1" | bc`

This will use bc instead of the shell for doing the computation.

edited Oct 3, 2012 at 8:43

answered Oct 2, 2012 at 21:37

usta

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3 Comments

arsenal Over a year ago

I have this as the first line in my script. #!/bin/bash. Will this not work?

usta Over a year ago

@user1419563 It will, provided that /bin/bash exists. However, as sehe already mentioned, it won't work if you invoke the script with sh explicitly.

arsenal Over a year ago

Updated my question with the error I am getting after making changes. Any suggestions will be of great help.

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