After editing the input file, the Athena executable can be run with the -i option to specify the name of the input file. For example, to run the Brio & Wu shocktube use

% athena -i ../tst/1D-mhd/athinput.brio-wu

The code will first echo the values of all input parameters to stdout. During the main integration loop it will print the cycle number, current and next timestep, and when it concludes it will print final diagnostic information.

A variety of command line options have been implemented in Athena. A list is given by the -h switch:

% athena -h
Athena version 4.0 - 01-JUN-2010
  Last configure: Thu Mar 25 22:15:28 EDT 2010

Usage: athena [options] [block/par=value ...]

  -i <file>       Alternate input file [athinput]
  -r <file>       Restart a simulation with this file
  -d <directory>  Alternate run dir [current dir]
  -h              This Help, and configuration settings
  -n              Parse input, but don't run program
  -c              Show Configuration details and quit
  -t hh:mm:ss     With MPI, wall time limit for final output

Configuration details:

 Problem:                 linear_wave1d
 Gas properties:          MHD
 Equation of State:       ADIABATIC
 Passive scalars:         0
 Self-gravity:            OFF
 Ohmic resistivity:       OFF
 Viscosity:               OFF
 Thermal conduction:      OFF
 Particles:               OFF
 Coordinate System:       Cartesian
 Special Relativity:      OFF
 Order of Accuracy:       2 (SECOND_ORDER_CHAR)
 Flux:                    roe
 Unsplit integrator:      ctu
 Precision:               DOUBLE_PREC
 Ghost cell Output:       OFF
 Parallel Modes: MPI:     OFF
 H-correction:            OFF
 FFT:                     OFF
 Shearing Box:            OFF
 FARGO:                   OFF
 All-wave integration:    OFF
 Static mesh refinement:  OFF

The -d option can be used to create a new directory in which Athena will run and write the output files. The -n option is useful for debugging any parsing errors, as it will dump the contents of all parsed block/parameters.

A value for any of the valid parameter names in the input file can also be input from the command line, this over-rides the values in the input file. This, in combination with the -d option, is useful for parameter surveys. The -c option is useful for checking the configuration parameters with which the executable was compiled.