How do you do math in bash?

How do you do math in bash?

The Bash shell has a large list of supported arithmetic operators to do math calculations….What are the Bash Arithmetic Operators?

Arithmetic Operator	Description
!, ~	logical and bitwise negation
**	exponentiation
*, /, %	multiplication, division, remainder (modulo)
+, –	addition, subtraction

What is arithmetic expansion in bash?

Arithmetic expansion allows the evaluation of an arithmetic expression and the substitution of the result. The format for arithmetic expansion is: $(( expression )) The expression is treated as if it were within double quotes, but a double quote inside the parentheses is not treated specially.

How do I add values to a variable in bash?

11 Answers

1. Use arithmetic expansion: $((EXPR)) num=$((num1 + num2)) num=$(($num1 + $num2)) # Also works num=$((num1 + 2 + 3)) # num=$[num1+num2] # Old, deprecated arithmetic expression syntax.
2. Using the external expr utility. Note that this is only needed for really old systems.

How do I sum two variables in bash?

Bash – Adding Two Numbers

1. Using expr command with quotes sum=`expr $num1 + $num2`
2. Use expr command inclosed with brackets and start with dollar symbol. sum=$(expr $num1 + $num2)
3. This is my preferred way to directly with the shell. sum=$(($num1 + $num2))

What are the two modes of operation in bash?

Bash provides two modes for command line editing – emacs and vi.

What does double parentheses mean in Bash?

Similar to the let command, the (( )) construct permits arithmetic expansion and evaluation. However, this double-parentheses construct is also a mechanism for allowing C-style manipulation of variables in Bash, for example, (( var++ )). …

How do I declare a variable in Bash?

To create a variable, you just provide a name and value for it. Your variable names should be descriptive and remind you of the value they hold. A variable name cannot start with a number, nor can it contain spaces. It can, however, start with an underscore.

How do I sum two variables in Bash?

How do you echo the value of a variable in Bash?

Now, using the echo command we can simply display its value on the terminal as follows:

1. $ var_a=100. $ echo $var_a.
2. $ var_b=” bash programming echo variable” $ echo $var_b.
3. $ var_A=”hellofriends” $ var_B=50. $ echo $var_A$var_B.
4. $ var1=$(date) $ var2=$(hostname) $ echo “the date is $var1 @ computer name is $var2”

How do you store variables in Bash?

Bash Assign Output of Shell Command To And Store To a Variable

1. var=$(command-name-here) var=$(command-name-here arg1) var=$(/path/to/command) var=$(/path/to/command arg1 arg2)
2. var=`command-name-here` var=`command-name-here arg1` var=`/path/to/command` var=`/path/to/command arg1 arg2`