Roll virtual dice.


Roll a single 20 sided dice

$ rolldice d[20]

Roll two six sided dice and drop the lowest roll
$ rolldice [2]d[6]s[1]

Roll two 20 sided dice and add a modifier value
$ rolldice [2]d[20][+5]

Roll a 20 sided dice two times
$ rolldice [2]xd[20]


rolldice [ options ] [dice_string [dice_string ...]]


rolldice rolls virtual dice. The dice strings passed on the command line contain information on the dice to roll in a format comparable to the format used in most role playing games.

If no dice strings are provided as command line arguments, rolldice uses stdin as input.



returns the usage of diceroll


returns the version of diceroll


uses /dev/random for random number generating


uses /dev/urandom for random number generating (default)


prints out the result of each individual die separately, as well as the operations and totals


prompts the user to input dice strings. Differs from normal stdin input in that errors do not cause the program to immediately exit, but rather return to the prompt.


The dice string uses the following format:


The dice string doesn't have to be in the exact format outlined above, but this is the order I use. It will try to parse any different string containing the same sections in the best way it can, and will throw out anything that isn't one of the sections below.


The first number is the number of dice to roll, and the second number is the number of sides the dice have. The numbers rolled on each die are then added up and given as the result. Hence 3d6 means "roll three six-sided dice, add them together and return the result". If the first number is left out, then the number of dice defaults to 1. If the second number is not a number, but a percentage sign (%), then the number of sides becomes 100 (for a percentage roll). If this is not included in the dice string, then the default is 1d6.


This number describes how many times to roll. For example, if you want to roll 3 6-sided dice 6 times, you use the dice string 6x3d6. This returns six numbers, corresponding to the six different rolls.


This number describes how many times to multiply the result of each roll. 3d6*100 returns a number in the range of 300-1800, because 3-18 is the range for 3d6 and the result is then multipled by 100.


This number is the modifier to be added or subtracted, depending on the sign, from each roll. 1d4+1 results in a range from 2-5 (1-4 for the die, plus 1). This step is handled *after* the multiplication modifier.


This number describes how many lowest dice rolls to drop. This step is handled *before* the multiplication modifier.

in the order show above. For an extreme example, "3x4d6*5+1s2" would roll four six-sided dice, drop the lowest two, multiply the result by 5, add 1 to that, and repeat the process two more times, for a total of three results.


The following error messages may appear on STDERR:

Requested * is too large

Memory could not be allocated while parsing the string passed to the rolldice program

Problems with the malformed dice string

The dice string contains a syntax error (see upper section DICE STRING FORMAT)

Unknown option

An unknown command-line option was provided

The exit values returned by rolldice follow the BSD convention.


1.16 - 18 Dec 2012


Stevie Strickland <>

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