System interface.
val argv : string array
The command line arguments given to the process. The first element is the command name used to invoke the program. The following elements are the command-line arguments given to the program.
val executable_name : string
The name of the file containing the executable currently running.
For all of the following functions, ?follow_symlinks defaults to true.
val file_exists : ?follow_symlinks:bool -> string -> [ `No | `Unknown | `Yes ]
file_exists ~follow_symlinks path

Test whether the file in path exists on the file system. If follow_symlinks is true and path is a symlink the result concerns the target of the symlink.

`Unknown is returned for files for which we cannot successfully determine whether they are on the system or not (e.g. files in directories to which we do not have read permission).

val file_exists_exn : ?follow_symlinks:bool -> string -> bool
Same as file_exists but blows up on `Unknown
val is_directory : ?follow_symlinks:bool -> string -> [ `No | `Unknown | `Yes ]
Returns `Yes if the file exists and is a directory
val is_file : ?follow_symlinks:bool -> string -> [ `No | `Unknown | `Yes ]
Returns `Yes if the file exists and is a regular file
val is_directory_exn : ?follow_symlinks:bool -> string -> bool
val is_file_exn : ?follow_symlinks:bool -> string -> bool
val remove : string -> unit
Remove the given file name from the file system.
val rename : string -> string -> unit
Rename a file. The first argument is the old name and the second is the new name. If there is already another file under the new name, rename may replace it, or raise an exception, depending on your operating system.
val getenv : string -> string option
Return the value associated to a variable in the process environment. Return None if the variable is unbound.
val getenv_exn : string -> string
val command : string -> int
Execute the given shell command and return its exit code.
command_exn command runs command and then raises an exception if it returns with nonzero exit status.
val command_exn : string -> unit
val chdir : string -> unit
Change the current working directory of the process.
val getcwd : unit -> string
Return the current working directory of the process.
val readdir : string -> string array
Return the names of all files present in the given directory. Names denoting the current directory and the parent directory ("." and ".." in Unix) are not returned. Each string in the result is a file name rather than a complete path. There is no guarantee that the name strings in the resulting array will appear in any specific order; they are not, in particular, guaranteed to appear in alphabetical order.
val fold_dir : init:'acc -> f:('acc -> string -> 'acc) -> string -> 'acc
val ls_dir : string -> string list
Same as readdir, but return a list rather than an array.
val interactive : bool ref
This reference is initially set to false in standalone programs and to true if the code is being executed under the interactive toplevel system ocaml.
val os_type : string
Operating system currently executing the Caml program. One of
  • "Unix" (for all Unix versions, including Linux and Mac OS X),
  • "Win32" (for MS-Windows, OCaml compiled with MSVC++ or Mingw),
  • "Cygwin" (for MS-Windows, OCaml compiled with Cygwin).
val word_size : int
Size of one word on the machine currently executing the Caml program, in bits: 32 or 64.
exception Break
Exception raised on interactive interrupt if Sys.catch_break is on.
val catch_break : bool -> unit
Warning: this function clobbers the Signal.int (SIGINT) handler. SIGINT is the signal that's sent to your program when you hit CTRL-C.

Warning: catch_break uses deep ocaml runtime magic to raise Sys.Break inside of the main execution context. Consider explicitly handling Signal.int instead. If all you want to do is terminate on CTRL-C you don't have to do any special setup, that's the default behavior.

catch_break governs whether interactive interrupt (ctrl-C) terminates the program or raises the Break exception. Call catch_break true to enable raising Break, and catch_break false to let the system terminate the program on user interrupt.

val ocaml_version : string
ocaml_version is the version of Objective Caml. It is a string of the form "major.minor[.patchlevel][+additional-info]", where major, minor, and patchlevel are integers, and additional-info is an arbitrary string. The [.patchlevel] and [+additional-info] parts may be absent.
val execution_mode : unit -> [ `Bytecode | `Native ]
execution_mode tests whether the code being executed was compiled natively or to bytecode.
val c_int_size : unit -> int
c_int_size returns the number of bits in a C int. Note that this can be different from word_size. For example, Linux x86-64 should have word_size = 64, but c_int_size () = 32