Multiplication on command line terminal

Question

I m using a serial terminal to provide input into our lab experiment  I found that using     echo  5X5    just returns a string of  5X5   Is there a command to execute a multiplication operation

User · Answer

For more advanced and precise math consider using bc 1    echo  3   2 19    bc -l  6 57

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The classical solution is   expr 5    5  expr will only work with integer operands   Another nice option is   echo 5 5  p   dc  dc can be made to work with non-integer operands

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Yes  you can use bash s built-in Arithmetic Expansion        to do some simple maths    echo     5   5    25   Check the Shell Arithmetic section in the Bash Reference Manual for a complete list of operators   For sake of completeness  as other pointed out  if you need arbitrary precision  bc or dc would be better

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I use this function which uses bc and thus supports floating point calculations   c           local a            gt  0     amp  amp  a         read -r -p  calc    a     bc -l  lt  lt  lt    a      Example     c  5 5  25   c 5 5 1 00000000000000000000   c 3 4 7 9  43037974683544303797   Bash s arithmetic expansion doesn t support floats  but Korn shell and zsh do    Example     ksh -c  echo     3 0   4     0 75

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A simple shell function  no sed needed  should do the trick of interpreting  5X5     function calc   bc -l  lt  lt  lt        xX           calc 5X5 25   calc 5x5 25   calc  5 5  25

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I have a simple script I use for this   me mycomputer    cat  usr local bin c     bin sh  echo        sed  s x    g    bc -l   It changes x to   since   is a special character in the shell   Use it as follows    c 5x5 c 5-4 2   1 c   5   5    30   you still have to use quotes if the expression contains any parentheses

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If you like python and have an option to install a package  you can use this utility that I made     install pythonp python -m pip install pythonp  pythonp  5 5  25  pythonp  1    1 math exp 0 5    0 3775406687981454    define a custom function and pass it to another higher-order function pythonp  n 10 functools reduce lambda x y x y  range 1 n 1         3628800

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Internal Methods  Bash supports arithmetic expansion with     expression     For example     echo     5   5    25   External Methods  A number of utilities provide arithmetic  including bc and expr     echo  5   5     usr bin bc 25     usr bin expr 5    5 25

[bash] Multiplication on command line terminal

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