bash.md

Echo

echo "Hello Wolrd"

Variable

W=7
echo "variable w = $W"

For loop

#!/bin/bash
for i in 1 2 3 4 5
    do
        echo "Welcome $i times"
done

OR

#!/bin/bash
for i in {1..5}
    do
        echo "Welcome $i times"
done

OR

#!/bin/bash
echo "Bash version ${BASH_VERSION}..."
for i in {0..10..2}
    do 
        echo "Welcome $i times"
done

IF statement

if [ $Var1 -gt 100 ]
then
    echo "Hey that\'s a large number."
    pwd
fi

OR

if [[ $VAR -gt 10 ]]
then
    echo "The variable is greater than 10."
else
    echo "The variable is equal or less than 10."
fi

OR

if [[ $VAR -gt 10 ]]
then
    echo "The variable is greater than 10."
elif [[ $VAR -eq 10 ]]
then
    echo "The variable is equal to 10."
else
    echo "The variable is less than 10."
fi

User Input

read Var
echo "$Var"

Arithemtic

#Using expr with backtick
Val1=`expr 30 / 10`
echo $Val1

#Using expr within command substitute
Val2=$( expr 30 - 10 )
echo $Val2

# Using 'let' command
let Val3=9*3
echo $Val3

# Using 'let' command
let "Val4 = 8 / 3"
echo $Val4

# Using argument value in arithmetic operation
let "Val5 = 50 + $Var1"
echo $Val5

# Calculate the mathematical expression
Val6=$((10*5+15))
echo $Val6

# Using post or pre increment/decrement operator
Val7=41
((Val7++))
echo $Val7
((--Val7))
echo $val7

# Using shorthand operator
(( val7 += 60 ))
echo $val7

# Dividing 40 by 6
(( Val8 = 40/6 ))
echo $val8

# Dividing 55 by 3 with bc only
echo "55/3" | bc

# Dividing 55 by 3 with bc and -l option
echo "55/3" | bc -l

Logical Operator

if [[ $varA == 1 && ($varB == "t1" || $varC == "t2") ]]; then