ocamlrun - The Objective Caml bytecode interpreter
ocamlrun [ options ] filename argument ...
The ocamlrun(1) command executes bytecode files produced by the linking
phase of the ocamlc(1) command.
The first non-option argument is taken to be the name of the file
containing the executable bytecode. (That file is searched in the
executable path as well as in the current directory.) The remaining
arguments are passed to the Objective Caml program, in the string array
Sys.argv. Element 0 of this array is the name of the bytecode
executable file; elements 1 to n are the remaining arguments.
In most cases, the bytecode executable files produced by the ocamlc(1)
command are self-executable, and manage to launch the ocamlrun(1)
command on themselves automatically.
The following command-line options are recognized by ocamlrun(1).
-b When the program aborts due to an uncaught exception, print a
detailed "back trace" of the execution, showing where the
exception was raised and which function calls were outstanding
at this point. The back trace is printed only if the bytecode
executable contains debugging information, i.e. was compiled and
linked with the -g option to ocamlc(1) set. This option is
equivalent to setting the b flag in the OCAMLRUNPARAM
environment variable (see below).
-I dir Search the directory dir for dynamically-loaded libraries, in
addition to the standard search path. -p Print the names of the
primitives known to this version of ocamlrun(1) and exit.
-v Direct the memory manager to print verbose messages on standard
error. This is equivalent to setting v=63 in the OCAMLRUNPARAM
environment variable (see below).
Print version and exit.
The following environment variable are also consulted:
Additional directories to search for dynamically-loaded
The directory containing the Objective Caml standard library.
(If OCAMLLIB is not set, CAMLLIB will be used instead.) Used to
locate the ld.conf configuration file for dynamic loading. If
not set, default to the library directory specified when
compiling Objective Caml.
Set the runtime system options and garbage collection
parameters. (If OCAMLRUNPARAM is not set, CAMLRUNPARAM will be
used instead.) This variable must be a sequence of parameter
specifications. A parameter specification is an option letter
followed by an = sign, a decimal number (or a hexadecimal number
prefixed by 0x), and an optional multiplier. There are nine
options, six of which correspond to the fields of the control
record documented in The Objective Caml users manual, chapter
"Standard Library", section "Gc".
b Trigger the printing of a stack backtrace when an uncaught
exception aborts the program. This option takes no argument.
p Turn on debugging support for ocamlyacc-generated parsers. When
this option is on, the pushdown automaton that executes the
parsers prints a trace of its actions. This option takes no
The policy used for allocating in the OCaml heap. Possible
values are 0 for the next-fit policy, and 1 for the first-fit
policy. Next-fit is somewhat faster, but first-fit is better
for avoiding fragmentation and the associated heap compactions.
The size of the minor heap (in words).
The default size increment for the major heap (in words).
The major GC speed setting.
The heap compaction trigger setting.
The limit (in words) of the stack size.
h The initial size of the major heap (in words).
What GC messages to print to stderr. This is a sum of values
selected from the following:
0x001 Start of major GC cycle.
0x002 Minor collection and major GC slice.
0x004 Growing and shrinking of the heap.
0x008 Resizing of stacks and memory manager tables.
0x010 Heap compaction.
0x020 Change of GC parameters.
0x040 Computation of major GC slice size.
0x080 Calling of finalisation functions.
0x100 Startup messages (loading the bytecode executable file,
resolving shared libraries).
The multiplier is k, M or G, for multiplication by 2^10, 2^20,
and 2^30 respectively. For example, on a 32-bit machine under
bash, the command export OCAMLRUNPARAM=’s=256k,v=1’ tells a
subsequent ocamlrun to set its initial minor heap size to 1
megabyte and to print a message at the start of each major GC
If OCAMLRUNPARAM is not found in the environment, then
CAMLRUNPARAM will be used instead. If CAMLRUNPARAM is not
found, then the default values will be used.
PATH List of directories searched to find the bytecode executable
The Objective Caml users manual, chapter "Runtime system".