Performing simple math calculations in 'sh"

[john guardian]

Hi. I usually use ksh, but need to run "sh" instead. As an example, I've used

typeset -i
typeset -i
=-
echo $

but that doesn't seem to be supported for sh.

Can anyone suggest an alternate method for performing this type of operation?

Would some form of "eval" work?

Thanks.

[A. Clay Stephenson · Accepted solution]

Note the "sh" in HP-UX does not mean the Bourne shell but rather the POSIX shell (which is all but identical to the Korn shell). Your syntax wouldn't work in ksh either.

typeset -i A=100
typeset -i B=50
typeset -i C=0

C=$((${A} - ${B}))
echo "Result = ${C}"

This syntax also works in ksh.

[James R. Ferguson]

Hi Joe:

One way:

# typeset -i var1=1
# typeset -i var2=3
# let var3=var1+var2
# echo ${var3}

Another way, in lieu of using 'let' is:

# var3=$(( $var1 + $var2 ))

Regards!

...JRF...

[Jonathan Fife]

I like:

$ echo $SHELL
/sbin/sh
$ var2=30
$ var3=15
$ (( var1 = var2 - var3 ))
$ echo $var1
15

[Carsten Krege]

You can use the following. Also see sh-posix manual page and seach for "Arithmetic Evaluation".

# i=$(( 5 + 6 ))
# echo $i
11
# i=$(( 5 - 6 ))
# echo $i
-1

# typeset -i a
# typeset -i b
# a=10
# b=12
# i=$(( $a - $b ))
# echo $i
-2

Carsten

[Bill Hassell]

There are 3 ways for shell arithmetic (which by the way is only integer, no fractions):

1. let A=$B+$C
2. A=$(($A+$B))
3. A=$(expr $B + $C)

[john guardian]

Hi. Thanks to all for input. Sorry about the points delay. The input for this has been running flawlessly. Regards.

[john guardian]

Thanks to all.