Script to insert line into files in sub-dirs

Question

I have a sub-dir tree with varying number of branches and most of the branches contain .cpp files (many of them). I have a header-file at the root of the tree that I want to have as a

#include "<constructed-relative-path-to-root>/headerfile.h"

as the first line of each .cpp.

an alternative to constructed-relative-path-to-root would be the hard-coded path, which would have to be adjusted whenever the project is relocated)

a second alternative would be to copy the content of the header-file in at the top of each .cpp file

I have no idea how to write such a script. Can anyone please help?

Answer 1

From the root of your tree run

find . -name \*cpp | while read FILE
do
    sed -i '1i #include "rootpath/headerfile.h"' "$FILE"
done

Answer 2

I got hold of this on CLUG-mailing list:

base=$(pwd)
find . -type f -iname '*.cpp' | while read f ; do
   curr=$(dirname $f)
   relpath=$(python -c "import os.path; print os.path.relpath('$base',
'$curr')")
   sed -i -e '1i#include "'$relpath/headerfile.h'"' "$f"
done

Copy the above code into a file, make it executable and run from commandline.

Answer 3

If your goal is to include a header file at the start of every source file you build, and you're using gcc, you don't need to change your files at all; you can simply add:

-include headerfile.h

to the gcc command line. From the man page:

   -include file
       Process file as if "#include "file"" appeared as the first line of
       the primary source file.  However, the first directory searched for
       file is the preprocessor's working directory instead of the
       directory containing the main source file.  If not found there, it
       is searched for in the remainder of the "#include "..."" search
       chain as normal.