# How to pass compiling and linking flags to fpm **URL:** \ **Category:** Help\ **Created:** [September 25, 2022, 2:53pm UTC](https://fortran-lang.discourse.group/t/how-to-pass-compiling-and-linking-flags-to-fpm/4404 "2022-09-25T14:53:23Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![icpup](https://avatars.discourse-cdn.com/v4/letter/i/e79b87/32.png) [@icpup](https://fortran-lang.discourse.group/u/icpup)\ **Post date:** [September 25, 2022, 2:53pm UTC](https://fortran-lang.discourse.group/t/how-to-pass-compiling-and-linking-flags-to-fpm/4404/1 "2022-09-25T14:53:24Z")
I have a local library and module files not in current working directory. I need compile and link a new project to this library using fpm. Where should I modify the fpm.toml or pass the flag to the fpm command? ---
**Author:** ![vmagnin](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/vmagnin/32/28_2.png) [@vmagnin](https://fortran-lang.discourse.group/u/vmagnin)\ **Post date:** [September 25, 2022, 5:00pm UTC](https://fortran-lang.discourse.group/t/how-to-pass-compiling-and-linking-flags-to-fpm/4404/2 "2022-09-25T17:00:09Z")
See [Manifest reference — Fortran Package Manager](https://fpm.fortran-lang.org/en/spec/manifest.html#specifying-dependencies) (specifying-dependencies) You can also use the `--flag` option, for example: ```bash $ fpm run --flag '$(pkg-config --cflags mylibrary)' ``` ---
**Author:** ![icpup](https://avatars.discourse-cdn.com/v4/letter/i/e79b87/32.png) [@icpup](https://fortran-lang.discourse.group/u/icpup)\ **Post date:** [September 25, 2022, 10:26pm UTC](https://fortran-lang.discourse.group/t/how-to-pass-compiling-and-linking-flags-to-fpm/4404/3 "2022-09-25T22:26:04Z")
The reason I am asking for help here is that it is difficult for me to understand some description in Manifest reference. Maybe I need some tutorials on how to link local library to a project. Anyway, here is my situation: I have a local library `libmylib.a` at `~/mine/lib` and the related mod files at `~/mine/include`. Based on [Manifest:link external library](https://fpm.fortran-lang.org/en/spec/manifest.html#link-external-libraries), the build section is modified as ```auto [build] link = "mylib" ``` However, where do I specify the the path for lib and mods? When compile and link using gfortran, the command used was `gfortran -I~/mine/include -L~/mine/lib main.f90 -lmylib` ---
**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:** [September 26, 2022, 10:53am UTC](https://fortran-lang.discourse.group/t/how-to-pass-compiling-and-linking-flags-to-fpm/4404/4 "2022-09-26T10:53:25Z")
There are a few different ways that this can be done in fpm. - If you have **local includes** specify them in the `"include-dir" = ["mylocalinc"]` keyword. Keep in mind this > _include-dir_ does not currently allow using pre-built module `.mod` files - If you have includes outside of your project either: - Use the fpm subcommand `--flag` to pass whatever compiler options you want to fpm - Set the shell variable `FPM_FFLAGS` to pass whatever compiler options you want to fpm - Or last option, that I do not recommend but I list for completeness, append/prepend to the variable your compiler uses to look for include paths for GNU (gfortran) that is `CPATH` e.g. CPATH=${CPATH}:/my/path For linking the options that you have are pretty much the same. In your `fpm.toml` add the lib you wish to link against to ```auto [build] link = ["mylib"] ``` - Use the fpm subcommand `--link-flag` e.g. `fpm build --link-flag "-L/path/to/mylib"` - Set `FPM_LDFLAGS` e.g. `export FPM_LDFLAGS="-L/path/to/mylib"` and then `fpm build` - Or set the compiler variables `LD_LIBRARY_PATH` (and for gfortran `LIBRARY_PATH`) to include your “/path/to/mylib” e.g. `export LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:/path/to/mylib`, `export LIBRARY_PATH=${LIBRARY_PATH}:/path/to/mylib` and then `fpm build` Here is an example where you link against an external library is [GitHub - gnikit/gmsh-fpm: Gmsh API using the Fortran Package Manager (fpm)](https://github.com/gnikit/gmsh-fpm) ---
**Author:** ![icpup](https://avatars.discourse-cdn.com/v4/letter/i/e79b87/32.png) [@icpup](https://fortran-lang.discourse.group/u/icpup)\ **Post date:** [September 26, 2022, 11:48am UTC](https://fortran-lang.discourse.group/t/how-to-pass-compiling-and-linking-flags-to-fpm/4404/5 "2022-09-26T11:48:08Z")
Thank you very much. Very clear description. ---
**Author:** ![ofmla](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/ofmla/32/3320_2.png) [@ofmla](https://fortran-lang.discourse.group/u/ofmla)\ **Post date:** [May 22, 2024, 7:06pm UTC](https://fortran-lang.discourse.group/t/how-to-pass-compiling-and-linking-flags-to-fpm/4404/6 "2024-05-22T19:06:14Z")
I’m trying to get rid of `-Werror=implicit-interface` flag when compiling a project and I am passing my compiler flags via `--flag "compiler flags option of my choice "` but the `--verbose` option shows me that the project is still being compiled with `-Werror=implicit-interface`. What can I do to get it `-Werror=implicit-interface` out of the way? ---
**Author:** ![everythingfunctional](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/everythingfunctional/32/176_2.png) [@everythingfunctional](https://fortran-lang.discourse.group/u/everythingfunctional)\ **Post date:** [May 22, 2024, 7:45pm UTC](https://fortran-lang.discourse.group/t/how-to-pass-compiling-and-linking-flags-to-fpm/4404/7 "2024-05-22T19:45:24Z")
You may want to try this: [Manifest reference — Fortran Package Manager](https://fpm.fortran-lang.org/spec/manifest.html#fortran-features)