Ok, lets create a single line of bash that will handle the -h option and print something.
First, what to print? I usually add some comments on the start of the file, so lets print that. Example script:
#!/bin/bash # # This is the doc of the script # the line that we will add code of script
Lets go step by step. We need to print the file it self:
Skip the first line (lets switch to sed):
sed -n '2,$ p' "$0"
Go until you find the first empty line:
sed -n '2,/^$/ p' "$0"
Remove the # fro the start of the line:
sed '2,/^$/ s/#// p' "$0"
Finally, we check if the -h is the first argument, print the thing and exit:
[ "$1" = '-h' ] && sed -n '2,/^$/ s/#// p' "$0" && exit