Generating a single LaTeX file by merging different LaTeX files

Generating a single LaTeX file by merging different LaTeX files

I have a main LaTeX file which inputs many other LaTeX files i.e. for example
\documentclass{article}
\begin{document}
\input{input1.tex}
\input{./Input_folder_1/input2.tex}
\input{input3.tex}
\input{./Input_folder_2/Input_folder_3/input4.tex}
\end{document}
Let's call the above file say main.tex. I want a single LaTeX file, which imports contents from input1.tex,input2.tex, input3.tex and input4.tex, so that I have only one single LaTeX file instead of the above four LaTeX files. How do I go about writing a bash-script which does this job for me?
PS: I need to submit an article a journal and I thought it would be good to have a single .tex file. The issue is the following. I have different files in sub-directories in a recursive manner and hence I cannot upload these individual files since the directory structure in the input command is on the local folder on my computer. I could of-course put these manually but I thought if there would be a way out similar to the .bbl file for the bibliography.