gmx mdrun error: "Error in user input: Invalid input values In option s" I'm new to bioinformatics and gromacs I tried to run the code and got this error
Program:     gmx mdrun, version 2020
Source file: src/gromacs/options/options.cpp (line 179)
Function:    void gmx::internal::OptionSectionImpl::finish()

Error in user input:
Invalid input values
In option s
Required option was not provided, and the default file 'topol' does not
exist or is not accessible.
The following extensions were tried to complete the file name:
  .tpr

I already have the file topol. I searched and found that I need to run mdrun-h to ensure that the command work but when I check
mdrun -h 

I got
mdrun: command not found
If the command line says &quot;command not found&quot;, it means that the binary is not executable or not found in any of the paths mentioned in the $PATH environmental variable. You can check for example this tutorial for details on how it works and how to resolve problems related to this variable.
Which probably means, that you need to go a step back, to the installation instructions of gromacs and try to install the mdrun binary. However, if the mdrun was not installed successfully, it's very likely that more stuff of the package will be missing, so it might be worth reinstalling it all.
P.S. It's not obvious to me if getting mdrun it will resolve the first posted problem (I have never worked with gromacs). If you would share the link to the research you have done, that would help others to help you.