parrot(1) Parrot Virtual Machine


parrot [-options] <file> [arguments ...]


Parrot is a virtual machine designed to efficiently compile and execute bytecode for dynamic languages. Parrot currently hosts a variety of language implementations in various stages of completion, including Tcl, Javascript, Ruby, Lua, Scheme, PHP, Python, Perl 6, APL, and a .NET bytecode translator. Parrot is not about parrots, but we are rather fond of them, for obvious reasons.


--help Print the option summary on the command line.
--version Print version information and exit.
--include Add "path" to the include search path.
--library Add "path" to the library search path.
--hash-seed [hexnum]
Sets the hash seed to the specified value. This option is useful for debugging intermittent failures, but should not be used in production. For more information about this option, see docs/dev/profiling.pod, docs/project/hacking_tips.pod, docs/running.pod, and docs/submissions.pod.
--dynext Add "path" to the dynamic extension search path.

Run core options

These options select the runcore, which is useful for performance tuning and debugging. For more information about these options, see the ``About runcores'' section in docs/running.pod.
--runcore [CORE]
Select the runcore. The following cores are available in Parrot, but not all may be available on your system:

  fast           bare-bones core without bounds-checking or
                 context-updating (default)
  slow, bounds   bounds checking core
  trace          bounds checking core with trace info
                 (see 'parrot --help-debug')
  profiling      see F<docs/dev/profiling.pod>
  subprof        subroutine-level profiler
                 (see POD in F<src/runcore/subprof.c>)
--profile Run with the slow core and print an execution profile.
--trace Run with the slow core and print trace information to stderr.
See "parrot --help-debug" for available flag bits.

VM options

Turn on interpreter debug flag. See "parrot --help-debug" for available flag bits.
--help-debug Print the summary of debugging and tracing flag bits.
--warnings Turn on warnings.
See "parrot --help-debug" for available flag bits.
--no-gc Turn off GC.
This may prove useful for finding GC-related bugs.
Do not use this option for longer running programs: since memory is no longer recycled, it may quickly become exhausted.
--gc [GC-type]

GC MS2 options

Maximum memory wasted by GC

GC GMS options

--gc-nursery-size=percent of system
Size of gen0 (default 2)
--gc-debug Turn on GC (Garbage Collection) debugging.
This imposes some stress on the GC subsystem and can considerably slow down execution.
Free all memory of the last interpreter. This is useful when running leak checkers.
--wait Read a keystroke before starting.
This is useful when you want to attach a debugger on platforms such as Windows.
Print the runtime prefix path and exit.
--numthreads <number>
Overrides the automatically detected number of CPU cores to set the number of OS threads. Minimum number: 2

Compiler options

Valid optimizer levels: "-O", "-O1", "-O2", "-Op"

-O1 enables the pre_optimizer, runs before control flow graph (CFG) is built. It includes strength reduction and rewrites certain if/branch/label constructs.

-O2 runs afterwards, handles constant propagation, jump optimizations, removal of unused labels and dead code.

-Op applies -O2 to pasm files also.

The old options -Oc and -Oj are currently ineffective.

-O defaults to -O1.

Turn on compiler debug flags. See "parrot --help-debug" for available flag bits.
Preprocess source file (expand macros) and print result to "stdout":

  $> parrot -E t/op/macro_10.pasm
  $> parrot -E t/op/macro_10.pasm | parrot -- -
--output=FILE Act like an assembler, but do not execute the code,
unless the -r is supplied as well. If 'outputfile' ends with .pbc, 'parrot' will write a PBC file. If it ends with .pasm, 'parrot' will output a PASM file, even from PASM input.
--output-pbc Act like an assembler, but always output bytecode,
even if the output file does not end in .pbc
--pasm Assume PASM input on "stdin".
--pbc Assume PBC file on "stdin" and execute it.
NOTE: If whitespace separates the -d switch from the argument, the argument must start with a number, i.e., a decimal digit.
--run-pbc Only useful after "-o" or "--output-pbc".
Execute the program from the compiled in-memory image. If two "-r" options are supplied, the .pbc file is read from disc and executed. This is needed, primarily, for tests.
--yydebug Turn on yydebug in yacc/bison.
--verbose Turn on compiler verbosity.


If the file ends in .pbc it will be interpreted immediately.

If the file ends in .pasm, then it is parsed as PASM code. Otherwise, it is parsed as PIR code. In both cases, it will then be executed, unless the "-o" flag was supplied.

If the "file" is a single dash, input from "stdin" is read.

[arguments ...]

Optional arguments passed to the running program as ARGV. The program is assumed to know what to do with the arguments.


If this environment variable is set, parrot will use this path as its runtime prefix instead of the compiled-in path. This is useful if you want to execute a version of parrot different from the one on the ``compiled-in'' path.
Turn on the --gc-debug flag.


For information on how to submit a bug report, see docs/submissions.pod.


Parrot is a product of the contributions of a great many people. For a list of most of these people, see CREDITS.


Copyright (C) 2001-2014, Parrot Foundation.