[gmx-developers] Compilation Errors When Using GROMACS Headers/Library

[Vladislav Martin]

Dear GROMACS developers,

I am writing code in C utilizing the GROMACS 5.1.2 library. The purpose of
the code is to read the binary data stored in GROMACS' XTC trajectory files
into C data types for further analysis / manipulation of the data.

*NOTE*: In case this would be important information, I followed the "Quick
and Dirty Installation"
<http://manual.gromacs.org/documentation/5.1.2/install-guide/index.html#quick-and-dirty-installation>
instructions for GROMACS 5.1.2 and all commands were executed in the
terminal successfully.

Back to the C code. At the very top of my file, I include
"/usr/local/gromacs/include/gromacs/fileio/xtcio.h" so that I may access
the functions I need to read the XTC trajectory files. I ran into an odd
error when attempting to compile my program.

""
$ gcc -o read_trajectory read_trajectory.c -L
/usr/local/gromacs/lib/x86_64-linux-gnu/ -lgromacs
In file included from read_trajectory.c:3:0:
/usr/local/gromacs/include/gromacs/fileio/xtcio.h:41:35: fatal error:
gromacs/fileio/gmxfio.h: No such file or directory
 #include "gromacs/fileio/gmxfio.h"
                                   ^
compilation terminated.
""

I can fix this error by running a bash command that searches recursively
through all header files in the "usr/local/gromacs/include/gromacs"
directory and replaces 'gromacs/' (which only shows up in #include
statements) with '/usr/local/gromacs/include/gromacs/' (or
'/path/to/your/installation/gromacs/include/gromacs/'). I have included
this bash command in case someone else experiences this compilation error
and wants to fix it quickly:

'""
$ sudo find /usr/local/gromacs/include/gromacs/ -name '*.h' -type f -exec
sed -i 's:gromacs/:/usr/local/gromacs/include/gromacs/:' {} \;
""

Once I run this command, the program compiles successfully and I am able to
run the resulting executable without any further errors.

What confuses me is that this error could have been fixed when the GROMACS
header files were created in the first place - I shouldn't have to fix the
relative paths where the header files are supposed to look for & find the
other GROMACS header files. From what I can tell (I read the #include
directives
<http://manual.gromacs.org/documentation/5.1.2/dev-manual/includestyle.html>),
every header file is contained within the
"/usr/local/gromacs/include/gromacs/" directory (or, more generally,
"/path/to/your/installation/gromacs/include/gromacs/"). Within that
directory there are modular directories that store related headers, like
"fileio/". Knowing all of this, why does an #include statement referring to
a GROMACS header file in that *same* directory say
"gromacs/fileio/gmxfio.h" - which, as a relative path, would *never* point
to the right directory - instead of "gmxfio.h" or "./gmxfio.h", which
actually reflects this file hierarchy?

In the end, my question is simple: did I miss something in the
documentation that informs me on how to include GROMACS headers files
properly so that I don't have to change the include statements myself?
Otherwise, is this a syntax bug that will be fixed in later GROMACS
versions?


Many thanks,

Vladislav Martin
Research Assistant
Center for Nanobiology and Structural Biology
Email: martin.vl at husky.neu.edu
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