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expr/bc syntax issue

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# 1  
Old 06-14-2010
expr/bc syntax issue
Hi,

I am facing issues in my shell script while trying to add two variables. Look at the snippet below for details:

# Initially variable SAMPLE1 and SAMPLE2 are set from different sources. Have trucated decimal to avoid numeric errors in expr
Code:
SAMPLE1=`/usr/bin/top -n 1 | head -3 | tail -1 | tr -d ' ' | cut -d"," -f4 | cut -d "%" -f1 | cut -d"." -f1`
SAMPLE2=`/usr/bin/top -n 1 | head -3 | tail -1 | tr -d ' ' | cut -d"," -f4 | cut -d "%" -f1 | cut -d"." -f1`
 
$  echo $SAMPLE1
96
$  echo $SAMPLE2
96

$  expr ${SAMPLE1} + ${SAMPLE2}
expr: non-numeric argument
 
$  echo "${SAMPLE1} + ${SAMPLE2}" | bc
(standard_in) 1: illegal character: ^[
(standard_in) 1: parse error
(standard_in) 1: illegal character: ^O
(standard_in) 1: illegal character: ^[
(standard_in) 1: parse error
(standard_in) 1: illegal character: ^[
(standard_in) 1: illegal character: ^O
(standard_in) 1: parse error
(standard_in) 1: illegal character: ^[
(standard_in) 1: illegal character: ^O
(standard_in) 1: illegal character: ^[
(standard_in) 1: parse error
(standard_in) 1: illegal character: ^[
(standard_in) 1: illegal character: ^O
(standard_in) 1: parse error

# However when set manually, it works.
Code:
$  SAMPLE1=96
$  SAMPLE2=96

$  expr ${SAMPLE1} + ${SAMPLE2}
192
$  echo "${SAMPLE1} + ${SAMPLE2}" | bc
192

Any suggestion to make this work?

Regards,
Animesh
Last edited by Franklin52; 06-14-2010 at 06:01 AM.. Reason: Please use code tags!
# 2  
Old 06-14-2010
Change
Code:
SAMPLE1=`/usr/bin/top -n 1 | head -3 | tail -1 | tr -d ' ' | cut -d"," -f4 | cut -d "%" -f1 | cut -d"." -f1`
SAMPLE2=`/usr/bin/top -n 1 | head -3 | tail -1 | tr -d ' ' | cut -d"," -f4 | cut -d "%" -f1 | cut -d"." -f1`

to
Code:
SAMPLE1=`/usr/bin/top -b -n 1 | head -3 | tail -1 | tr -d ' ' | cut -d"," -f4 | cut -d "%" -f1 | cut -d"." -f1`
SAMPLE2=`/usr/bin/top -b -n 1 | head -3 | tail -1 | tr -d ' ' | cut -d"," -f4 | cut -d "%" -f1 | cut -d"." -f1`

This User Gave Thanks to bartus11 For This Post:
animesh303
# 3  
Old 06-14-2010
Thanks!!! That works. Just wondering what was the issue over here?

I assume the result fetched by my query was text rather than a numeral?
# 4  
Old 06-14-2010
No. Your query fetched characters used by top to control behaviour of the terminal. With -b option top's output is clear from those characters, so it can be saved to file or used in shell scripts.
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