Not working echo 'expr $a + $b' in linux 5.0.

venkatesh51 · 10-23-2012, 06:15 AM

Hi all,

Please help me in this small issue, i tried 2-3hrs to find the solution but not abled filnally.
Q: Not working a=20 b=10 echo 'expr $a + $b' in linux 5.0 but working without echo?

colucix · 10-23-2012, 07:06 AM

You have to use backticks not single quotes around the expr command:

Code:

echo `expr $a + $b`

If using bash you can use the "new" syntax for command substitution, that is $(command) in place of the backticks. Moreover, you may consider the arithmetic operator $((expression)), e.g.

Code:

echo $((a + b))

If compatibility with the older Bourne shell /bin/sh is requested, then stick with backticks and expr.

venkatesh51 · 10-23-2012, 07:36 AM

Quote:

Originally Posted by colucix

You have to use backticks not single quotes around the expr command:

Code:

echo `expr $a + $b`

If using bash you can use the "new" syntax for command substitution, that is $(command) in place of the backticks. Moreover, you may consider the arithmetic operator $((expression)), e.g.

Code:

echo $((a + b))

If compatibility with the older Bourne shell /bin/sh is requested, then stick with backticks and expr.

Thanks it is working....

H_TeXMeX_H · 10-23-2012, 08:01 AM

The best thing to do is not use back ticks, because they are deprecated for this very reason.

Code:

echo $(expr $a + $b)