How can I do division with variables in a Linux shell

Question

When I run commands in my shell as below  it returns an expr  non-integer argument error  Can someone please explain this to me     x 20   y 5   expr x   y  expr  non-integer argument

User · Accepted Answer

Those variables are shell variables   To expand them as parameters to another program  ie expr   you need to use the   prefix   expr  x    y   The reason it complained is because it thought you were trying to operate on alphabetic characters  ie non-integer   If you are using the Bash shell  you can achieve the same result using expression syntax   echo    x   y     Or   z    x   y   echo  z

User · Answer

To get the numbers after decimal point  you can do this - read num1 num2 div  echo  num1    num2   bc -l  echo  div

User · Answer

Referencing Bash Variables Requires Parameter Expansion  The default shell on most Linux distributions is Bash  In Bash  variables must use a dollar sign prefix for parameter expansion  For example   x 20 y 5 expr  x    y   Of course  Bash also has arithmetic operators and a special arithmetic expansion syntax  so there s no need to invoke the expr binary as a separate process  You can let the shell do all the work like this   x 20  y 5 echo    x   y

User · Answer

Why not use let  I find it much easier  Here s an example you may find useful   start  date   s        do something that takes a while     sleep 71  end  date   s  let deltatime end-start let hours deltatime 3600 let minutes  deltatime 60  60 let seconds deltatime 60 printf  Time spent   d  02d  02d n   hours  minutes  seconds   Another simple example - calculate number of days since 1970   let days   date   s  86400

User · Answer

let s suppose  x 50 y 5   then   z    x y     this will work properly   But if you want to use     operator  in case statements than it can t resolve it   In that case use simple strings like div or devide or something else  See the code

User · Answer

I believe it was already mentioned in other threads   calc    awk  BEGIN   print              then you can simply type    calc 7 5 3 2   2 34375   In your case it will be   x 20  y 3  calc  x  y   or if you prefer  add this as a separate script and make it available in  PATH so you will always have it in your local shell      bin bash calc    awk  BEGIN   print

[linux] How can I do division with variables in a Linux shell?

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