convert string into number by shell

[mystical dervish]

Hello,
By Shell script, I get a substring from string, where the substring is surely a number, but I can't do mathematical expression on those variables that have the substring
the code is

#!/bin/sh
p1=`grep -w lala lev_prob.txt | awk '{z=$2}END{if($z=="") print "0"; else print z}'`
p2=`grep -w lala irq_prob.txt | awk '{z=$2}END{if($z=="") print "0"; else print z}'`
echo $p1$p2        // it prints well
echo "------------"
tmp= `expr $p1 / $p2`  // gives error says expr: non-numeric argument

echo $tmp   // no out

can someone help

thanx

[Franklin52]

Hello,
By Shell script, I get a substring from string, where the substring is surely a number, but I can't do mathematical expression on those variables that have the substring
the code is

#!/bin/sh
p1=`grep -w lala lev_prob.txt | awk '{z=$2}END{if($z=="") print "0"; else print z}'`
p2=`grep -w lala irq_prob.txt | awk '{z=$2}END{if($z=="") print "0"; else print z}'`
echo $p1$p2        // it prints well
echo "------------"
tmp= `expr $p1 / $p2`  // gives error says expr: non-numeric argument

echo $tmp   // no out

can someone help

thanx

You have a space after the "=" sign, try this:

tmp=`expr $p1 / $p2`

instead of:

tmp= `expr $p1 / $p2`

Regards

[mystical dervish]

You have a space after the "=" sign, try this:

tmp=`expr $p1 / $p2`

instead of:

tmp= `expr $p1 / $p2`

Regards

thanx
I did so , but it doesn't work
the same error

[Franklin52]

Strange, it should work, what are the values of $p1 and $p2?

<EDIT>

PS:

p2=`grep -w lala irq_prob.txt | awk '{z=$2}END{if($z=="") print "0"; else print z}'`

If this is a zero, you'll divide $p1 by zero........

</EDIT>


Regards

[mystical dervish]

Strange, it should work, what are the values of $p1 and $p2?

Regards

$p1=0.0011602
$p2=0.0006459360
really its strange !!!!

[Franklin52]

$p1=0.0011602
$p2=0.0006459360
really its strange !!!!

Not so strange, Bash can't handle floating point calculations, use bc:

tmp=`echo $p1 / $p2 | bc -l`

instead of:

tmp=`expr $p1 / $p2`

Regards

[mystical dervish]

Strange, it should work, what are the values of
<EDIT>
PS:

p2=`grep -w lala irq_prob.txt | awk '{z=$2}END{if($z=="") print "0"; else print z}'`

If this is a zero, you'll divide $p1 by zero........

</EDIT>

THANKS
you are right, may be I'll put a very small valus instead of zero.
regards

but still have a pb of non-numeric argument

[Franklin52]

THANKS
you are right, may be I'll put a very small valus instead of zero.
regards

but still have a pb of non-numeric argument

Have you seen my previous post?

Regards

[mystical dervish]

Not so strange, Bash can't handle floating point calculations, use bc:

tmp=`echo $p1 / $p2 | bc -l`

instead of:

tmp=`expr $p1 / $p2`

Regards

cheer, it works well, thank you.But I have got another problem that I don't know if its related to what you have solved
when I check the value of tmp in a condition it's always true whereas its not
for example

p1=$(grep -w $line lev_prob.txt | awk '{z=$2}END{if($z=="") print "0.000001"; else print z}')
p2=$(grep -w $line irq_prob.txt | awk '{x=$2}END{if($x=="") print "0.000001"; else print x}')
p3=$(grep -w $line eyr_prob.txt ......so on 

p12=`echo $p1 / $p2 | bc -l`
p13=`echo $p1 / $p3 | bc -l`

echo $p12" " $p13" // prints out 1.315218339  .88775928139

if [ $p12 > 1.5 -a $p13 > 1.5 ]
then 	echo "you are here"
else 
echo "not true"
fi

it prints out always "you are here" where it must go to else !
is there any syntatic pb ? where I tried "$p12" > "1.5" but it doesnt help

thanx in advance

[vsemaska]

Check you current directory, you should find a file named 1.5. That's what the '> 1.5' is doing. To get it to work, change the if statement to:

if [[ $p12 > 1.5 ]] && [[ $p13 > 1.5 ]]

But that won't always work because the if statement is comparing strings, not numbers. You'd have to use the bc utility to do the test.

Also put a 'set -vx' at the beginning of the script and it'll show what it's doing.

Vic