Numbers and Arithmetic in bash: Difference between revisions

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More about {{Internal|expr|expr}}
More about {{Internal|expr|expr}}
=Integral Number Operations=
==$((...))==
==eval==


=Floating Point Operations=
=Floating Point Operations=

Revision as of 19:21, 5 May 2020

Internal

How to Tell if a Variable has an Integer Value

v=10

if expr ${v} + 1 >/dev/null 2>&1; then
    #
    # the value contained by v is an integer
    #
else
    #
    # the value contained by v is NOT an integer
    #
fi

More about

expr

Integral Number Operations

$((...))

eval

Floating Point Operations

Multiplication:

local operand1=10.1
local operand2=20.2

result=$(echo ${operand1} ${operand2} | awk '{printf "%5.1f\n",$1*$2}') || exit 1

Division:

local operand1=10.1
local operand2=20.2

result=$(echo ${operand1} ${operand2} | awk '{printf "%5.1f\n",$1/$2}') || exit 1

Increment an Integer

Increment an Integer with ((...)) Operator

Decrement an Integer

Decrement an Integer with ((...)) Operator

Numeric Evaluation in a Condition

a=1
b=2
if [[ $(expr ${a} - ${b}) < 0 ]]; then
  ...
fi

Random Numbers

Bash script that generates a random MAC address

Organizatorium

local t0="$(date -u +%s)"
local t1="$(date -u +%s)"
local delta="$(bc <<<"${t1}-${t0}")"