Bash Floating Point Math With Variables

02 Sep, 2021

The following commands show how to perform floating point arithmetic addition subtraction multiplication and division using the Ruby programming language at the bash prompt. Bash cant handle floating point calculations and it lacks operators for certain important mathematical functions.

What Is The Bash Null Command Learn About The Bash Null Command Also Known As The Posix Shell Colon Command This Post Cover Concrete Command Use Case Linux

Then echo 2 Expected two arguments exit 1 fi x1 y2 sum bc.

Bash floating point math with variables. Bash does not support floating point operations. There must be a way to do this and yes. However what if we use floating point in Bash shell.

Note the use of the backtick myvarcommand syntax to assign the results of the arithmetic to a bash variable. Integers are natively supported in Bash shell. Bash supports redirections so we can feed the floating point computations and the math functions into some other programs input who understands it.

This may come as a surprise but Bash only supports integer arithmetic natively. Then echo As expected 100 is greater than 90 fi a120 b30 c float_eval a b The code for the functions follows. A noteworthy but unconventional way to do floating-point arithmetic in native bash is to combine Arithmetic Expansion with printf using the scientific notation.

Fortunately bc gallops to the rescue. If you for example want two decimals use 2f instead of f. Timestep0125 i2 t echo timestep i awk printf 43fn12.

Not just a versatile arbitrary precision calculation utility bc offers many of the facilities of a programming language. Usage is quite simple. Modify the printf formatting string to suit your needs.

As a quick proof to yourself try multiplying integers then do the same with floating point numbers. The short and direct answer is using bc command An arbitrary precision calculator language Just run bc and enter some floating point calculation expression such as 1282 bc will give the result. Float_eval 120 30 if float_cond 100 90.

If you need to perform calculations on floating point numbers you will need to call out to a utility program like bcor Python. To do floating point calculations in a shell script you can invoke awk eg. Since you cant do floating-point in bash you would just apply a given multiplier by a power of 10 to your math operation inside an Arithmetic Expansion then use printf to display the float.

Binbash if 2. RemainingTime durationnumOfRevisionsremainingRevision echo remainingTime 60 minutes and remainingTime 60 seconds remaining All variables are integer numbers duration is the number of seconds My problem is to calculate the variable remaining time so as to use print formatted in the second line. Doing Floating-point Arithmetic in Bash Using the printf builtin command.

This is where the problem is encountered and we cannot write a math function of our own. Binbash Floating point number functions. With intermediate variables.

Or you can use bc calculations see man bc for details.

Bash Declare Command Linux Hint

Bash Math How To Perform Math Operations In Bash The Easy Way Youtube

How To Format Date And Time In Linux Macos And Bash Find Out How To Manipulate Date And Time On Linux And Macos Systems As Well As Nativ Linux Dating Format

Iterate And Check If A Bash Array Contains A Value Learn How To Use Bash Array Variables And Associative Bas Regular Expression Being Used Quotes Single Words