Sys (melange.Stdlib.Sys)

let argv: array(string);

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.

let 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.

let file_exists: string => bool;

Test if a file with the given name exists.

let 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.

since 3.10

let is_regular_file: string => bool;

Returns true if the given name refers to a regular file, false if it refers to another kind of file.

raises Sys_error
if no file exists with the given name.

since 5.1

let remove: string => unit;

Remove the given file name from the file system.

let rename: string => string => unit;

Rename a file or directory. rename oldpath newpath renames the file or directory called oldpath, giving it newpath as its new name, moving it between (parent) directories if needed. If a file named 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

let getenv: string => string;

Return the value associated to a variable in the process environment.

raises Not_found
if the variable is unbound.

let getenv_opt: string => option(string);

Return the value associated to a variable in the process environment or None if the variable is unbound.

since 4.05

let 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.

let time: unit => float;

Return the processor time, in seconds, used by the program since the beginning of execution.

let chdir: string => unit;

Change the current working directory of the process.

let mkdir: string => int => unit;

Create a directory with the given permissions.

since 4.12

let rmdir: string => unit;

Remove an empty directory.

since 4.12

let getcwd: unit => string;

Return the current working directory of the process.

let readdir: string => array(string);

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.

let interactive: ref(bool);

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.

alert unsynchronized_access The interactive status is a mutable global state.

let 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-w64),
"Cygwin" (for MS-Windows, OCaml compiled with Cygwin).

type backend_type =

| Native
| Bytecode
| Other(string)

;

Currently, the official distribution only supports Native and Bytecode, but it can be other backends with alternative compilers, for example, javascript.

since 4.04

let backend_type: backend_type;

Backend type currently executing the OCaml program.

since 4.04

let unix: bool;

True if Sys.os_type = "Unix".

since 4.01

let win32: bool;

True if Sys.os_type = "Win32".

since 4.01

let cygwin: bool;

True if Sys.os_type = "Cygwin".

since 4.01

let word_size: int;

Size of one word on the machine currently executing the OCaml program, in bits: 32 or 64.

let int_size: int;

Size of int, in bits. It is 31 (resp. 63) when using OCaml on a 32-bit (resp. 64-bit) platform. It may differ for other implementations, e.g. it can be 32 bits when compiling to JavaScript.

since 4.03

let big_endian: bool;

Whether the machine currently executing the Caml program is big-endian.

since 4.00

let max_string_length: int;

Maximum length of strings and byte sequences.

let 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.

let 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.

let 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.

since 4.03

let runtime_parameters: unit => string;

Return the value of the runtime parameters, in the same format as the contents of the OCAMLRUNPARAM environment variable.

since 4.03

Signal handling

type signal_behavior =

| Signal_default
| Signal_ignore
| Signal_handle(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.

let 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.

let set_signal: int => signal_behavior => unit;

Same as Sys.signal but return value is ignored.

Signal numbers for the standard POSIX signals.

let sigabrt: int;

Abnormal termination

let sigalrm: int;

Timeout

let sigfpe: int;

Arithmetic exception

let sighup: int;

Hangup on controlling terminal

let sigill: int;

Invalid hardware instruction

let sigint: int;

Interactive interrupt (ctrl-C)

let sigkill: int;

Termination (cannot be ignored)

let sigpipe: int;

Broken pipe

let sigquit: int;

Interactive termination

let sigsegv: int;

Invalid memory reference

let sigterm: int;

Termination

let sigusr1: int;

Application-defined signal 1

let sigusr2: int;

Application-defined signal 2

let sigchld: int;

Child process terminated

let sigcont: int;

Continue

let sigstop: int;

Stop

let sigtstp: int;

Interactive stop

let sigttin: int;

Terminal read from background process

let sigttou: int;

Terminal write from background process

let sigvtalrm: int;

Timeout in virtual time

let sigprof: int;

Profiling interrupt

let sigbus: int;

Bus error

since 4.03

let sigpoll: int;

Pollable event

since 4.03

let sigsys: int;

Bad argument to routine

since 4.03

let sigtrap: int;

Trace/breakpoint trap

since 4.03

let sigurg: int;

Urgent condition on socket

since 4.03

let sigxcpu: int;

Timeout in cpu time

since 4.03

let sigxfsz: int;

File size limit exceeded

since 4.03

exception Break;

Exception raised on interactive interrupt if Sys.catch_break is on.

let 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.

let 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 was absent before version 3.08.0 and became mandatory from 3.08.0 onwards. The [(+|~)additional-info] part may be absent.

let development_version: bool;

true if this is a development version, false otherwise.

since 4.14

type extra_prefix =

| Plus
| Tilde
/*
- since 4.14
*/

;

type extra_info = (extra_prefix, string);

since 4.14

type ocaml_release_info = {

major: int,
minor: int,
patchlevel: int,
extra: option(extra_info),

};

since 4.14

let ocaml_release: ocaml_release_info;

ocaml_release is the version of OCaml.

since 4.14

let 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.

since 4.03

alert unsynchronized_access The status of runtime warnings is a mutable global state.

let runtime_warnings_enabled: unit => bool;

Return whether runtime warnings are currently enabled.

since 4.03

alert unsynchronized_access The status of runtime warnings is a mutable global state.

Optimization

let 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 ()))
done

since 4.03

module Immediate64: { ... };

This module allows to define a type t with the immediate64 attribute. This attribute means that the type is immediate on 64 bit architectures. On other architectures, it might or might not be immediate.