unwanted_line1=blabla
unwanted_line2=blabla
my_variable=important_content_section1
important_content_section2
important_content_section3
unwanted_line3=blabla

##</code><code>##

unwanted_line1=blabla
unwanted_line2=blabla
my_variable=important_content_section1
important_content_section2
important_content_section3
[stepxyz#xxxx]

##</code><code>##

my ($getVariable) = $data =~ /(my_variable=.*\n(.+[^=]\n?)*)/;

##</code><code>##

unwanted_line1=blabla
unwanted_line2=blabla
my_variable=important_content_section1
important_content_section2
important_content_section3
unwanted_line3=
##</code><code>##

my_variable=important_content_section1
important_content_section2
important_content_section3