1Sys(3) OCamldoc Sys(3)
2
6 Sys - System interface.
7
9 Module Sys
10
12 Module Sys
13 : sig end
14 System interface.
17 Every function in this module raises Sys_error with an informative mes‐
19 sage when the underlying system call signal an error.
20 val argv : string array
27 The command line arguments given to the process. The first element is
29 the command name used to invoke the program. The following elements
30 are the command-line arguments given to the program.
31 val executable_name : string
35 The name of the file containing the executable currently running.
37 val file_exists : string -> bool
41 Test if a file with the given name exists.
43 val is_directory : string -> bool
47 Returns true if the given name refers to a directory, false if it
49 refers to another kind of file. Raise Sys_error if no file exists with
50 the given name.
51 Since 3.10.0
54 val remove : string -> unit
58 Remove the given file name from the file system.
60 val rename : string -> string -> unit
64 Rename a file. The first argument is the old name and the second is the
66 new name. If there is already another file under the new name, rename
67 may replace it, or raise an exception, depending on your operating sys‐
68 tem.
69 val getenv : string -> string
73 Return the value associated to a variable in the process environment.
75 Raise Not_found if the variable is unbound.
76 val getenv_opt : string -> string option
80 Return the value associated to a variable in the process environment or
82 None if the variable is unbound.
83 Since 4.05
86 val command : string -> int
90 Execute the given shell command and return its exit code.
92 val time : unit -> float
96 Return the processor time, in seconds, used by the program since the
98 beginning of execution.
99 val chdir : string -> unit
103 Change the current working directory of the process.
105 val getcwd : unit -> string
109 Return the current working directory of the process.
111 val readdir : string -> string array
115 Return the names of all files present in the given directory. Names
117 denoting the current directory and the parent directory ( . and .. in
118 Unix) are not returned. Each string in the result is a file name
119 rather than a complete path. There is no guarantee that the name
120 strings in the resulting array will appear in any specific order; they
121 are not, in particular, guaranteed to appear in alphabetical order.
122 val interactive : bool Pervasives.ref
126 This reference is initially set to false in standalone programs and to
128 true if the code is being executed under the interactive toplevel sys‐
129 tem ocaml .
130 val os_type : string
134 Operating system currently executing the OCaml program. One of
136 - Unix (for all Unix versions, including Linux and Mac OS X),
138 - Win32 (for MS-Windows, OCaml compiled with MSVC++ or Mingw),
140 - Cygwin (for MS-Windows, OCaml compiled with Cygwin).
142 type backend_type =
146 | Native
147 | Bytecode
148 | Other of string
149 Currently, the official distribution only supports Native and Bytecode
152 , but it can be other backends with alternative compilers, for example,
153 javascript.
154 Since 4.04.0
157 val backend_type : backend_type
161 Backend type currently executing the OCaml program.
163 Since 4.04.0
166 val unix : bool
170 True if Sys.os_type = Unix .
172 Since 4.01.0
175 val win32 : bool
179 True if Sys.os_type = Win32 .
181 Since 4.01.0
184 val cygwin : bool
188 True if Sys.os_type = Cygwin .
190 Since 4.01.0
193 val word_size : int
197 Size of one word on the machine currently executing the OCaml program,
199 in bits: 32 or 64.
200 val int_size : int
204 Size of an int. It is 31 bits (resp. 63 bits) when using the OCaml
206 compiler on a 32 bits (resp. 64 bits) platform. It may differ for
207 other compilers, e.g. it is 32 bits when compiling to JavaScript.
208 Since 4.03.0
211 val big_endian : bool
215 Whether the machine currently executing the Caml program is big-endian.
217 Since 4.00.0
220 val max_string_length : int
224 Maximum length of strings and byte sequences.
226 val max_array_length : int
230 Maximum length of a normal array. The maximum length of a float array
232 is max_array_length/2 on 32-bit machines and max_array_length on 64-bit
233 machines.
234 val runtime_variant : unit -> string
238 Return the name of the runtime variant the program is running on. This
240 is normally the argument given to -runtime-variant at compile time, but
241 for byte-code it can be changed after compilation.
242 Since 4.03.0
245 val runtime_parameters : unit -> string
249 Return the value of the runtime parameters, in the same format as the
251 contents of the OCAMLRUNPARAM environment variable.
252 Since 4.03.0
255 === Signal handling ===
260 type signal_behavior =
263 | Signal_default
264 | Signal_ignore
265 | Signal_handle of (int -> unit)
266 What to do when receiving a signal:
269 - Signal_default : take the default behavior (usually: abort the pro‐
271 gram)
272 - Signal_ignore : ignore the signal
274 - Signal_handle f : call function f , giving it the signal number as
276 argument.
277 val signal : int -> signal_behavior -> signal_behavior
282 Set the behavior of the system on receipt of a given signal. The first
284 argument is the signal number. Return the behavior previously associ‐
285 ated with the signal. If the signal number is invalid (or not available
286 on your system), an Invalid_argument exception is raised.
287 val set_signal : int -> signal_behavior -> unit
291 Same as Sys.signal but return value is ignored.
293 === Signal numbers for the standard POSIX signals. ===
298 val sigabrt : int
301 Abnormal termination
303 val sigalrm : int
307 Timeout
309 val sigfpe : int
313 Arithmetic exception
315 val sighup : int
319 Hangup on controlling terminal
321 val sigill : int
325 Invalid hardware instruction
327 val sigint : int
331 Interactive interrupt (ctrl-C)
333 val sigkill : int
337 Termination (cannot be ignored)
339 val sigpipe : int
343 Broken pipe
345 val sigquit : int
349 Interactive termination
351 val sigsegv : int
355 Invalid memory reference
357 val sigterm : int
361 Termination
363 val sigusr1 : int
367 Application-defined signal 1
369 val sigusr2 : int
373 Application-defined signal 2
375 val sigchld : int
379 Child process terminated
381 val sigcont : int
385 Continue
387 val sigstop : int
391 Stop
393 val sigtstp : int
397 Interactive stop
399 val sigttin : int
403 Terminal read from background process
405 val sigttou : int
409 Terminal write from background process
411 val sigvtalrm : int
415 Timeout in virtual time
417 val sigprof : int
421 Profiling interrupt
423 val sigbus : int
427 Bus error
429 Since 4.03
432 val sigpoll : int
436 Pollable event
438 Since 4.03
441 val sigsys : int
445 Bad argument to routine
447 Since 4.03
450 val sigtrap : int
454 Trace/breakpoint trap
456 Since 4.03
459 val sigurg : int
463 Urgent condition on socket
465 Since 4.03
468 val sigxcpu : int
472 Timeout in cpu time
474 Since 4.03
477 val sigxfsz : int
481 File size limit exceeded
483 Since 4.03
486 exception Break
490 Exception raised on interactive interrupt if Sys.catch_break is on.
493 val catch_break : bool -> unit
497 catch_break governs whether interactive interrupt (ctrl-C) terminates
500 the program or raises the Break exception. Call catch_break true to
501 enable raising Break , and catch_break false to let the system termi‐
502 nate the program on user interrupt.
503 val ocaml_version : string
507 ocaml_version is the version of OCaml. It is a string of the form
510 major.minor[.patchlevel][+additional-info] , where major , minor , and
511 patchlevel are integers, and additional-info is an arbitrary string.
512 The [.patchlevel] and [+additional-info] parts may be absent.
513 val enable_runtime_warnings : bool -> unit
517 Control whether the OCaml runtime system can emit warnings on stderr.
519 Currently, the only supported warning is triggered when a channel cre‐
520 ated by open_* functions is finalized without being closed. Runtime
521 warnings are enabled by default.
522 Since 4.03.0
525 val runtime_warnings_enabled : unit -> bool
529 Return whether runtime warnings are currently enabled.
531 Since 4.03.0
534 === Optimization ===
539 val opaque_identity : 'a -> 'a
542 For the purposes of optimization, opaque_identity behaves like an
544 unknown (and thus possibly side-effecting) function.
545 At runtime, opaque_identity disappears altogether.
547 A typical use of this function is to prevent pure computations from
549 being optimized away in benchmarking loops. For example: for _round =
550 1 to 100_000 do ignore (Sys.opaque_identity (my_pure_computation ()))
551 done
552 Since 4.03.0
5562018-04-14 source: Sys(3)