It is obvious error there could be 2 reasons for this error.
1st: Either you should have mention /split in case /split is a mount point.
2nd: Or if your objective is to place files into current directory, where a directory named split is present. Then you have to make sure first directory split is present in current directory or make sure you have this directory present into your current directory.
Also your commands seems to be we could improve them in case you could let us know your complete objective like what you are trying to do with Input_file's data? Please do let us know more details with all conditions and samples(in code tags), so that we could help you more.
What do you want to escape?
What is ./split2.sh: line 1: ?
Does whatever your Code is work with the first eleven lines in your "source" (which I guess is called "commontypes.txt")?
How is line 12 different?