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Simple arithmetic in shell

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Operating Systems Linux Fedora Simple arithmetic in shell
# 1  
Old 05-22-2009
Simple arithmetic in shell
Hey, I just wanted to know how one can write simple arithmetic like addition, subtraction, multiplication and division in shell-script.
# 2  
Old 05-22-2009
Code:
matt@matt-macbook$ cat math.sh
#!/bin/sh

NUMBER1=10
NUMBER2=5

((sum=NUMBER1-NUMBER2))
echo $sum
echo "\n"

((difference=NUMBER1-NUMBER2))
echo $difference
echo "\n"

((product=NUMBER1*NUMBER2))
echo $product
echo "\n"

((quotient=NUMBER1/NUMBER2))
echo $quotient
echo "\n"

# 3  
Old 05-22-2009
you can use different commnds such as
1)expr
2)bc
3)shell ("echo $((4+5))")

likewise..
read man page for more info
# 4  
Old 05-22-2009
Thanks. What if I want to perform more than one operation in an equation. Like I want to do (9*10)/100. I just learnt that expr \* is used for multiplication and expr / for division but the bracket doesn't work here so what do you use instead? Like I want to output (9*10)/100.
# 5  
Old 05-22-2009
Hey sorry, thanks. Without a bracket, it works. So you just say 9*\10 /100.

Just another questions: how can I get the lines of a command in man page. Like I just typed man expr and I want to know the number of lines that come in that command, and then maybe number of the string division in that man page of the command.
# 6  
Old 05-22-2009
Hey I learnt now how to perform basic threat. However I am stuck with doing basic arithmetic for non-integer values. For example I want to perform the operation (120/220) *100.
# 7  
Old 05-22-2009
The shell usually can't do floating-point operations. Use bc for that, eg
Code:
VAR=$( echo "(120/220)*100" | bc )
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