I need to pass three operands from command line in format number operator number example 25 + 25 how can this be done ?

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I need to create a shell script and pass three arguments in the format number operator number ,example:25 * 25 and perform calculation based on the operator and if operator not present then dispaly Unknown operator. How can it be done ??

What I have tried:

#!/bin/sh
result=0
if [$2 = + ]
then
result=$(($1 + $3))
echo $result
elif [$2 = - ]
then
result=$(($1 - $3))
echo $result
elif [$1 * $3 ]
then
result=$(($1 * $3)
echo $result
else
echo "Unknown Operator"
fi

Posted 11-Feb-21 1:19am

Ziad Ahmed Khan

Updated 11-Feb-21 1:44am

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Richard MacCutchan · Answer 1 · 2021-02-11T01:44:00

This is similar to your question of yesterday and a few simple typing errors need fixing:

Bash

#!/bin/sh
result=0
if [ "$2" = + ]
then
	result=$(($1 + $3))
	echo $result
elif [ "$2" = - ]
then
	result=$(($1 - $3))
	echo $result
elif [ "$2" = x ]
then
	result=$(($1 * $3))
	echo $result
else
	echo "Unknown Operator"
fi

Note, as I mentioned yesterday the expressions in square brackets require spaces after the opening bracket and before the closing one. And $((e)) expressions require two closing parentheses. Please try at least desk checking your code.

And the '*' character has a special meaning to the shell so cannot be used in the command line. I have used a small x instead.