Sys - System interface.
: sig end
Every function in this module raises Sys_error with an informative message when the underlying system call signal an error.
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. This name may be absolute or relative to the current directory, depending on the platform and whether the program was compiled to bytecode or a native executable.
val file_exists : string -> bool
Test if a file with the given name exists.
val is_directory : string -> bool
Returns true if the given name refers to a directory, false if it refers to another kind of file.
Raises Sys_error if no file exists with the given name.
val remove : string -> unit
Remove the given file name from the file system.
val rename : string -> string -> unit
Rename a file. rename oldpath newpath renames the file called oldpath , giving it newpath as its new name, moving it between directories if needed. If newpath already exists, its contents will be replaced with those of oldpath . Depending on the operating system, the metadata (permissions, owner, etc) of newpath can either be preserved or be replaced by those of oldpath .
Since 4.06 concerning the "replace existing file" behavior
val getenv : string -> string
Return the value associated to a variable in the process environment.
Raises Not_found if the variable is unbound.
val getenv_opt : string -> string option
Return the value associated to a variable in the process environment or None if the variable is unbound.
val command : string -> int
Execute the given shell command and return its exit code.
The argument of Sys.command is generally the name of a command followed by zero, one or several arguments, separated by whitespace. The given argument is interpreted by a shell: either the Windows shell cmd.exe for the Win32 ports of OCaml, or the POSIX shell sh for other ports. It can contain shell builtin commands such as echo , and also special characters such as file redirections > and < , which will be honored by the shell.
Conversely, whitespace or special shell characters occurring in command names or in their arguments must be quoted or escaped so that the shell does not interpret them. The quoting rules vary between the POSIX shell and the Windows shell. The Filename.quote_command performs the appropriate quoting given a command name, a list of arguments, and optional file redirections.
val time : unit -> float
Return the processor time, in seconds, used by the program since the beginning of execution.
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 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 OCaml 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).
type backend_type =
| Other of string
val backend_type : backend_type
Backend type currently executing the OCaml program.
val unix : bool
True if Sys.os_type = "Unix" .
val win32 : bool
True if Sys.os_type = "Win32" .
val cygwin : bool
True if Sys.os_type = "Cygwin" .
val word_size : int
Size of one word on the machine currently executing the OCaml program, in bits: 32 or 64.
val int_size : int
val big_endian : bool
Whether the machine currently executing the Caml program is big-endian.
val max_string_length : int
Maximum length of strings and byte sequences.
val max_array_length : int
Maximum length of a normal array (i.e. any array whose elements are not of type float ). The maximum length of a float array is max_floatarray_length if OCaml was configured with --enable-flat-float-array and max_array_length if configured with --disable-flat-float-array .
val max_floatarray_length : int
Maximum length of a floatarray. This is also the maximum length of a float array when OCaml is configured with --enable-flat-float-array .
val runtime_variant : unit -> string
Return the name of the runtime variant the program is running on. This is normally the argument given to -runtime-variant at compile time, but for byte-code it can be changed after compilation.
val runtime_parameters : unit -> string
Return the value of the runtime parameters, in the same format as the contents of the OCAMLRUNPARAM environment variable.
type signal_behavior =
| Signal_handle of (int -> unit)
What to do when receiving a signal:
- Signal_default : take the default behavior (usually: abort the program)
- Signal_ignore : ignore the signal
- Signal_handle f : call function f , giving it the signal number as argument.
val signal : int -> signal_behavior -> signal_behavior
Set the behavior of the system on receipt of a given signal. The first argument is the signal number. Return the behavior previously associated with the signal. If the signal number is invalid (or not available on your system), an Invalid_argument exception is raised.
val set_signal : int -> signal_behavior -> unit
Same as Sys.signal but return value is ignored.
Signal numbers for the standard POSIX signals.¶
val sigabrt : int
val sigalrm : int
val sigfpe : int
val sighup : int
Hangup on controlling terminal
val sigill : int
Invalid hardware instruction
val sigint : int
Interactive interrupt (ctrl-C)
val sigkill : int
Termination (cannot be ignored)
val sigpipe : int
val sigquit : int
val sigsegv : int
Invalid memory reference
val sigterm : int
val sigusr1 : int
Application-defined signal 1
val sigusr2 : int
Application-defined signal 2
val sigchld : int
Child process terminated
val sigcont : int
val sigstop : int
val sigtstp : int
val sigttin : int
Terminal read from background process
val sigttou : int
Terminal write from background process
val sigvtalrm : int
Timeout in virtual time
val sigprof : int
val sigbus : int
val sigpoll : int
val sigsys : int
Bad argument to routine
val sigtrap : int
val sigurg : int
Urgent condition on socket
val sigxcpu : int
Timeout in cpu time
val sigxfsz : int
File size limit exceeded
Exception raised on interactive interrupt if Sys.catch_break is on.
val catch_break : bool -> unit
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 OCaml. 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] part is absent for versions anterior to 3.08.0. The [(+|~)additional-info] part may be absent.
val enable_runtime_warnings : bool -> unit
Control whether the OCaml runtime system can emit warnings on stderr. Currently, the only supported warning is triggered when a channel created by open_* functions is finalized without being closed. Runtime warnings are disabled by default.
val runtime_warnings_enabled : unit -> bool
Return whether runtime warnings are currently enabled.
val opaque_identity : 'a -> 'a
For the purposes of optimization, opaque_identity behaves like an unknown (and thus possibly side-effecting) function.
At runtime, opaque_identity disappears altogether.
A typical use of this function is to prevent pure computations from being optimized away in benchmarking loops. For example:
for _round = 1 to 100_000 do
ignore (Sys.opaque_identity (my_pure_computation ()))
module Immediate64 : sig end