Defining Variables

#!/bin/bash
# Define Variables
p=$(pwd)
one=$(ls)
wi=$(whoami)
d=$(date)

# The brackets $(...) are necessary for command substitution.

echo "Run variables tasks"
echo                            # empty line 
echo $p
echo $one
echo $wi
echo $d
echo $c

Input/Output

read

#!/bin/bash
a=$(hostname)
echo
echo Hi my server name is $a
echo What is your name?
read b
echo Hi $b, Nice meeting with you.

if-else Statement

if [condition]
then
   statement1
else
   statement2
fi

Eg:

#!/bin/bash
count=100
if [ $count -eq 100 ]
then 
    echo count is 100
else
    echo count is NOT 100
fi

#Output:
mypc@mypc:~/tmp$ ./script.sh
count is 100

For Loops

Keep running until a specified number or variable value is met.

For example:

• If variable = 10, then run the script 10 times.
• If variable = green, blue, red, then run the script 3 times, once for each color.

for item in list
do
    # Code to be executed on each iteration
done

#Example 
for i in 1 2 3 4 5
do
    echo $i
done

While Loop

The while loop allows you to execute a block of code as long as a certain condition is true.

while condition
do
    # Code to be executed
done

Accessing Data From a File