SMASH can be run simply by executing the binary without any options (i.e. there are no required arguments). It does require an input file, though (see Configuration). Per default, the input file is expected in the current working directory with the name 'config.yaml'.

The following options are supported:

Short Variant	Long Variant	Documentation
`-h`	`--help`	Prints usage information and quits the program.
`-v`	`--version`	Prints the version of SMASH and quits the program.
`-i <file>`	`--inputfile <file>`	Overrides the location of the default '`config.yaml`' input file. The input settings will be read from the specified file instead.
`-d <file>`	`--decaymodes <file>`	The default decay modes are compiled in. With this argument you can override the decay modes to the exact set defined in the file. Multiple `-d` arguments are not supported.
`-p <file>`	`--particles <file>`	The default particle data is compiled in. With this argument you can override the particles to the exact set defined in the file. Multiple `-p` arguments are not supported.
`-c <YAML string>`	`--config <YAML string>`	The string argument to `-c` contains YAML markup to override input key values of the input file (`-i`) and/or supply additional keys. Multiple `-c` arguments are supported. Later specified values of the same key will override preceding settings. This can be a handy way to test different scenarios from a script.
`-m <modus>`	`--modus <modus>`	This is a shortcut for `-c 'General: { Modus: <modus> }'`. Note that `-m` always overrides `-c`.
`-e <time>`	`--endtime <time>`	This is a shortcut for `-c 'General: { End_Time: <time> }'`. Note that `-e` always overrides `-c`.
`-o <dir>`	`--output <dir>`	Sets the output directory. The default output directory is `./data/<runid>`, where `<rundid>` is an automatically incrementing integer. Note that this might cause races if several instances of SMASH run in parallel. In that case, make sure to specify a different output directory for every instance of SMASH.
`-l <dir>`	`--list-2-to-n <dir>`	Dumps the list of all possible 2 → n reactions (n > 1). Note that resonance decays and formations are NOT dumped. Every particle available in SMASH is collided against every and reactions with non-zero cross-section are dumped. Both colliding particles are assigned momenta from 0.1 to 10 GeV in the opposite directions to scan the possible √S.
`-r <pdg>`	`--resonance <pdg>`	Dumps the width(m) and m * spectral function(m^2) versus resonance mass m.
`-s <pdg1>,<pdg2>[,mass1,mass2]`	`--cross-sections <pdg1>,<pdg2>[,mass1,mass2[,plab1,...]]`	Dumps all the partial cross-sections of `<pdg1> + <pdg2>` with masses `mass1` and `mass2`. Masses are optional, default values are pole masses. Optionally, the lab frame momenta (fixed target) in GeV can be specified. The value of `plab1` depends on the order of the particles. The first particle is considered to be the projectile, the second one the target. These cross sections are not rescaled to match the parametrized total.
`-f`	`--force`	Forces overwriting files in the output directory.
`-S <pdg1>,<pdg2>[,mass1,mass2]`	`--cross-sections-fs <pdg1>,<pdg2>[,mass1,mass2[,plab1,...]]`	Dumps an approximation of the final-state cross-sections of `<pdg1> + <pdg2>` with masses `mass1` and `mass2`. Masses are optional, default values are pole masses. Optionally, the lab frame momenta (fixed target) in GeV can be specified. The value of `plab1` depends on the order of the particles. The first is considered to be the projectile, the second one the target. After the initial collision, only decays are considered and all resonances are assumed to have their pole mass. This may yield different results than a full simulation with SMASH, where the resonances masses are sampled from the spectral function. Typically, this results in errors of less than 1 mb in the worst case. Also, contributions from strings are not considered, and the values are not rescaled to match the parametrized total cross section.
`-f`	`--force`	Forces overwriting files in the output directory. Normally, if you specify an output directory with `-o`, the directory must be empty. With `-f` this check is skipped.
`-n`	`--no-cache`	Don't cache integrals in form of tabulations on the disk. Usually, in order for future smash runs to save computational time, the tabulations folder is created next to the output directory and contains the results of integrals stored in many different files. Using this option, such a folder is not created.
`-q`	`--quiet`	Quiets the disclaimer for scenarios where no printout is wanted. To get no printout, you also need to disable logging from the config.