# Fpm usage for already-written code **URL:** \ **Category:** fpm\ **Created:** [January 10, 2023, 2:30pm UTC](https://fortran-lang.discourse.group/t/fpm-usage-for-already-written-code/5004 "2023-01-10T14:30:10Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Shahid](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/shahid/32/3672_2.png) [@Shahid](https://fortran-lang.discourse.group/u/Shahid)\ **Post date:** [January 10, 2023, 2:30pm UTC](https://fortran-lang.discourse.group/t/fpm-usage-for-already-written-code/5004/1 "2023-01-10T14:30:10Z")
I’d like to know how to run the already-written code with fpm. The link [https://fpm.fortran-lang.org/en/tutorial/hello-fpm.html](https://fpm.fortran-lang.org/en/tutorial/hello-fpm.html) only demonstrates how to start a new project with fpm The second question is related to this output ![tree](https://global.discourse-cdn.com/free1/uploads/fortran_lang/original/2X/2/2352a51dcb902f7607a5087ad606cada8cc10b4a.png) What does the **tree** represent in the upper link? It does not look like a command here! > I am using Windows OS. ---
**Author:** ![FedericoPerini](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/federicoperini/32/1750_2.png) [@FedericoPerini](https://fortran-lang.discourse.group/u/FedericoPerini)\ **Post date:** [January 10, 2023, 2:36pm UTC](https://fortran-lang.discourse.group/t/fpm-usage-for-already-written-code/5004/2 "2023-01-10T14:36:14Z")
Are you using MSYS2? If so, you can install the tree utility by running ```auto pacman -S tree ``` ---
**Author:** ![gnikit](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/gnikit/32/1213_2.png) [@gnikit](https://fortran-lang.discourse.group/u/gnikit)\ **Post date:** [January 10, 2023, 6:28pm UTC](https://fortran-lang.discourse.group/t/fpm-usage-for-already-written-code/5004/3 "2023-01-10T18:28:51Z")
For already existing projects you will need to define a fpm.toml with all the location of your source files. That might not necessarily play nice with your existing project structure. You might want to have a look at one of my open source repos that takes an existing repo and repackages it for fpm > **[GitHub - gnikit/metis-fpm: The METIS partitioning library with a Fortran and...](https://github.com/gnikit/metis-fpm)** > > The METIS partitioning library with a Fortran and C API packaged for fpm - GitHub - gnikit/metis-fpm: The METIS partitioning library with a Fortran and C API packaged for fpm If you have your source files under `src` it’s probably going to be a lot easier to build with fpm. The thing that you will probably miss is defining a set of compile flags, but we are in the process of getting that working in a future release. ---
**Author:** ![Shahid](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/shahid/32/3672_2.png) [@Shahid](https://fortran-lang.discourse.group/u/Shahid)\ **Post date:** [January 11, 2023, 9:32am UTC](https://fortran-lang.discourse.group/t/fpm-usage-for-already-written-code/5004/4 "2023-01-11T09:32:21Z")
Thank you for the link; I’ll look into it. However, it does not appear to be simple. ---
**Author:** ![urbanjost](https://avatars.discourse-cdn.com/v4/letter/u/0ea827/32.png) [@urbanjost](https://fortran-lang.discourse.group/u/urbanjost)\ **Post date:** [January 11, 2023, 1:31pm UTC](https://fortran-lang.discourse.group/t/fpm-usage-for-already-written-code/5004/5 "2023-01-11T13:31:14Z")
In many cases I start with “fpm new DIRNAME” or “fpm new . --backfill” in an existing directory. Without seeing your original file structure I am not positive that is better than manually creating the subdirectories, etc. I have found it simplest in most cases to start that way. I am curious why you did not use “fpm new” as it might point towards ways to improve that subcommand. ---
**Author:** ![Shahid](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/shahid/32/3672_2.png) [@Shahid](https://fortran-lang.discourse.group/u/Shahid)\ **Post date:** [January 13, 2023, 3:31pm UTC](https://fortran-lang.discourse.group/t/fpm-usage-for-already-written-code/5004/6 "2023-01-13T15:31:55Z")
![files](https://global.discourse-cdn.com/free1/uploads/fortran_lang/original/2X/9/94a896e8a0a164a7554ece7f2060e313ceb97650.png) **main.f90** is the program and the rest are all modules. So how do I work with it? ---
**Author:** ![urbanjost](https://avatars.discourse-cdn.com/v4/letter/u/0ea827/32.png) [@urbanjost](https://fortran-lang.discourse.group/u/urbanjost)\ **Post date:** [January 13, 2023, 11:20pm UTC](https://fortran-lang.discourse.group/t/fpm-usage-for-already-written-code/5004/7 "2023-01-13T23:20:10Z")
If there are no other restrictions, change to the directory, backfill it, move the files into the expected locations and run, like this: ```bash cd $TO_THE_DIRECTORY fpm new . --backfill mv main.f90 app/ mv *mod.f90 src/ fpm run ``` Those are the ULS (Unix-Like Systems) commands; but the only thing that would vary would be the move commands; which have to be OS-specific. ---
**Author:** ![Shahid](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/shahid/32/3672_2.png) [@Shahid](https://fortran-lang.discourse.group/u/Shahid)\ **Post date:** [January 14, 2023, 9:10am UTC](https://fortran-lang.discourse.group/t/fpm-usage-for-already-written-code/5004/8 "2023-01-14T09:10:37Z")
It is working fine now ![fpm](https://global.discourse-cdn.com/free1/uploads/fortran_lang/original/2X/0/014b8a230b89c453636fe30931334abdc425916f.png) but seems like **fpm** is a bit slower ![gfortran](https://global.discourse-cdn.com/free1/uploads/fortran_lang/original/2X/f/f1512bb68b2a1a6342a783d62357ae2d075fa141.png) ---
**Author:** ![ivanpribec](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/ivanpribec/32/3290_2.png) [@ivanpribec](https://fortran-lang.discourse.group/u/ivanpribec)\ **Post date:** [January 14, 2023, 11:58am UTC](https://fortran-lang.discourse.group/t/fpm-usage-for-already-written-code/5004/9 "2023-01-14T11:58:28Z")
Try with ```plaintext $ fpm run --profile release ``` The meaning is the following: ```plaintext --profile PROF selects the compilation profile for the build. Currently available profiles are "release" for high optimization and "debug" for full debug options. If --flag is not specified the "debug" flags are the default. ``` (For fpm developers, should the `--flag` in the last sentence of the description be `--profile`?) ---
**Author:** ![urbanjost](https://avatars.discourse-cdn.com/v4/letter/u/0ea827/32.png) [@urbanjost](https://fortran-lang.discourse.group/u/urbanjost)\ **Post date:** [January 14, 2023, 2:24pm UTC](https://fortran-lang.discourse.group/t/fpm-usage-for-already-written-code/5004/10 "2023-01-14T14:24:25Z")
It’s correct but a little confusing. If --flag is specified no profile is applied unless specified. This allows you complete control of the compiler options. If --flag is not specified the default is --profile debug. So if --flag is specified and no profile is specified only the options specified with --flag are applied. If both are specified the options from the profile are combined with the options specified with --flag. ```bash fpm run ### same as "fpm run --profile debug" fpm run --flag '-Wall -O3' ## only the options specified are applied fpm run --flag "-march=broadwell" --profile release # use options from release profile plus specified option. ```