Assignment-01-A

echo "Hello, World!"

ls
ls -l  # long listing format
ls -a  # all files including hidden files

echo "Enter your name: "
read name
echo "Hello, $name!"

cat filename.txt
cat file1.txt file2.txt > combined.txt

touch newfile.txt

test -f filename.txt && echo "File exists."

for i in 1 2 3 4 5
do
  echo "Number: $i"
done

counter=1
while [ $counter -le 5 ]
do
  echo "Counter: $counter"
  ((counter++))
done

a=5
b=10
if [ $a -lt $b ]
then
  echo "$a is less than $b"
fi

if [ $a -lt $b ]
then
  echo "$a is less than $b"
else
  echo "$a is not less than $b"
fi

echo "Enter a number between 1 and 3:"
read num
case $num in
  1) echo "You entered one.";;
  2) echo "You entered two.";;
  3) echo "You entered three.";;
  *) echo "Invalid number.";;
esac

grep "pattern" file.txt
grep -i "pattern" file.txt  # case insensitive

sed 's/old/new/' file.txt  # replace first occurrence of 'old' with 'new'
sed 's/old/new/g' file.txt  # replace all occurrences of 'old' with 'new'

# Create files
touch file1.txt file2.txt
 
# List files in long format
ls -l
 
# Read user input
echo "Enter your favorite color: "
read color
echo "Your favorite color is $color."
 
# Concatenate file contents
echo "Hello" > file1.txt
echo "World" > file2.txt
cat file1.txt file2.txt > combined.txt
cat combined.txt
 
# Conditional and Arithmetic Comparison
a=3
b=7
if [ $a -lt $b ]
then
  echo "$a is less than $b"
fi
 
# Loop through numbers
for i in {1..5}
do
  echo "Number: $i"
done
 
# Search pattern in a file
echo "apple" > fruits.txt
echo "banana" >> fruits.txt
grep "apple" fruits.txt
 
# Substitute text in a file
echo "The sky is blue." > sentence.txt
sed 's/blue/clear/' sentence.txt