jocamlrun(1) The JoCaml bytecode interpreter


jocamlrun [ -v ] filename argument ...


The jocamlrun(1) command executes bytecode files produced by the linking phase of the jocamlc(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 jocamlc(1) command are self-executable, and manage to launch the jocamlrun(1) command on themselves automatically.


The following command-line option is recognized by jocamlrun(1).

When set, the memory manager prints verbose messages on standard error to signal garbage collections and heap extensions.


The following environment variable are also consulted:

Set the 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, and an optional multiplier. There are seven options:
b (backtrace)
Print a stack backtrace in case of an uncaught exception.
s (minor_heap_size)
Size of the minor heap.
i (major_heap_increment)
Minimum size increment for the major heap.
o (space_overhead)
The major GC speed setting.
O (max_overhead)
The heap compaction trigger setting.
l (stack_limit)
The limit (in words) of the stack size.
The initial size of the major heap (in words).
v (verbose)
What GC messages to print to stderr. This is a sum of values selected from the following:
Start of major GC cycle.
Minor collection and major GC slice.
Growing and shrinking of the heap.
Resizing of stacks and memory manager tables.
Heap compaction.
Change of GC parameters.
Computation of major GC slice size.
Calling of finalisation function.
Startup messages.

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 jocamlrun to set its initial minor heap size to 1 megabyte and to print a message at the start of each major GC cycle.

List of directories searched to find the bytecode executable file.