Ignore lines starting with # while reading a file in groovy - jenkins

Question

I'm writing a code in groovy to read a file line by line and perform an action (for ex: build a code for a specific configuration) based on the information available in the line.
The following groovy code runs fine for me, except that i want to ignore or skip the first line or rather any line which starts with # or comment (//).
__SAMPLE_GROOVY_CODE__
input_file = '/home/user/inputFile.txt'
// read all the lines into a list, each line is an element in the list
File FH1 = new File(input_file)
def lines = FH1.readLines()
for (line in lines)
{
env.c_num = sh(returnStdout: true, script: "echo '${line}' | cut -d ':' -f 1").trim();
env.p_num = sh(returnStdout: true, script: "echo '${line}' | cut -d ':' -f 2").trim();
env.p_len = p_num.length();
println("INFO: Length is ${p_len} \n");
if(env.p_len != '0')
{
println ("INFO: Build is required !! \n");
println ("INFO: c_num is: ${c_num} \n");
println ("INFO: p_num is: ${p_num} \n");
// Code for build will come here..!!
}
else
{
println("INFO: Build is NOT required !! \n");
}
}
__INPUT_FILE__
$> cat /home/user/inputFile.txt
# Details of inputFile.txt
1234-A0: aa ab ac ad ae al
5678-B0:
2345-B0: ba
3456-B0:
4567-B0: ca