Help on bash converting c to f degrees

JurassicPark · 09-13-2016, 10:43 PM

The error that I'm receiving is
./celsius_to_fahrenheit.sh line 13: bc: command not found
I'm not sure how to fix this. Please help

#!/bin/bash

#Variable to hold user option, initially it is 1
option=1

#Loop till option is 0
until [ $option -eq 0 ]

do
#Prompting user to enter temperature in centigrades
echo -n "\n Input Centigrade temperature value: "

#Reading temperature in centigrades
read centigrade

#Converting temperature from Centigrade to Fahrenheit
fahrenheit=$(echo "scale=2;((9/5) * $centigrade) + 32" |bc)

#Displaying temperature
echo "\n Temperature in Fahrenheit: $fahrenheit "

#Prompting user option
echo -n "\n Press (1 - Continue 0 - Exit): "

#Reading user option
read option
done

Shadow_7 · 09-13-2016, 11:12 PM

# apt-get install bc

# pacman -S bc

And probably other ways. Bash can handle non-floating point math.

Code:

#!/bin/bash
CELCIUS=20
FAHRENHEIT=68

# F to C
TEMP1=$(echo $(( $FAHRENHEIT - 32 )))
TEMP2=$(echo $(( $TEMP1 * 5 )))
echo "C =" $(( $TEMP2 / 9 ))

# C to F
TEMP1=$(echo $(( $CELCIUS * 9 )))
TEMP2=$(echo $(( $TEMP1 / 5 )))
echo "F =" $(( $TEMP2 + 32 ))

exit 0

You can fake floating point by adding a few zeros to the starting number. And manually adding the decimal when outputted. Otherwise you need "bc" to do floating point in various scripting languages like bash. Which is NOT installed by default on many minimum / headless installs.

Shadow_7 · 09-13-2016, 11:36 PM

The fake floating point version:

Code:

#!/bin/bash
CELCIUS=21
FAHRENHEIT=70
OFFSET=32

# as many zeroes as you want decimal places, within limits ofc
FAKINGIT=1000000

C1=$(( $CELCIUS * $FAKINGIT ))
F1=$(( $FAHRENHEIT * $FAKINGIT ))
O1=$(( $OFFSET * $FAKINGIT ))

# F to C
TEMP1=$(echo $(( $F1 - $O1 )))
TEMP2=$(echo $(( $TEMP1 * 5 )))
TEMP3=$(echo $(( $TEMP2 / 9 )))
echo "F="$FAHRENHEIT "C =" $(( $TEMP3 / $FAKINGIT ))"."$(( $TEMP3 % $FAKINGIT ))

# C to F
TEMP1=$(echo $(( $C1 * 9 )))
TEMP2=$(echo $(( $TEMP1 / 5 )))
TEMP3=$(echo $(( $TEMP2 + $O1 )))
echo "C="$CELCIUS "F =" $(( $TEMP3 / $FAKINGIT ))"."$(( $TEMP3 % $FAKINGIT ))

exit 0

grail · 09-13-2016, 11:53 PM

I understand that some times error messages can be a bit obtuse or even misleading, but this particular message could not have been any clearer.

chrism01 · 09-15-2016, 03:39 AM

If you've got a Centos/RHEL v6 system, it should be in /usr/bin/bc - you may need to check your $PATH.
Its in the base repo, so its unusual for it not to be installed.

Keith Hedger · 09-15-2016, 03:58 AM

The echo is redundant eg:

Code:

keithhedger@severnet ~ $ TEMP1=$(echo $(( 100 - 50 )))
keithhedger@severnet ~ $ echo $TEMP1
50
keithhedger@severnet ~ $ TEMP1=$(( 100 - 50 ))
keithhedger@severnet ~ $ echo $TEMP1
50

aragorn2101 · 09-15-2016, 05:17 AM

Quote:

Originally Posted by JurassicPark

The error that I'm receiving is
./celsius_to_fahrenheit.sh line 13: bc: command not found
I'm not sure how to fix this. Please help
done

Hi,

You need to install bc.

But I would like to add: why do you do these kinds of operations in Bash?

Bash is not exactly intended for this kind of programming. If low level languages like C is inaccessible to you, then try Python. It's faily easy and you will be able to do so much more.