kbbgl

# match 0 or more times using * quantifier
echo "hello, how are you?" | grep -e "[a-z]*" # will match hello, how, are, you

# match all numbers in chunks with length of one or more with + quantifier
echo "47427 8381481 5813471" | grep -P "[0-9]+" 
echo "47427 8381481 5813471" | grep -P "\d+" 

kbbgl

# using the ? means that we're not matching greedily

echo "<p>Paragraph 1</p><p>Paragraph 2</p><p>Paragraph 3</p>" | grep -P "<p>.*?</p>" # will match <p>Paragraph 1</p>, <p>Paragraph 2</p>, <p>Paragraph 3</p>

# we can use the ? to match an optional character

echo "http:\\website.com,https:\\website2.com" | grep -P "https?.*"

kbbgl

# using the {x} will match whatever comes before it x amount of times
echo "12341234444412354444" | grep -P "4{3}" # will match 3 times '444'


# using the {x,y} will match a range from x to y
echo "12341234444344412354444" | grep -P "4{1,4}" # will match 4, 4444, 444, 4444[

kbbgl

# use {x,} to match string with x+ characters
echo "hello world reallylongword" | grep -P "\w{6,}" -o # will match reallylongword