1Sys(3) OCaml library 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. This
37 name may be absolute or relative to the current directory, depending on
38 the platform and whether the program was compiled to bytecode or a
39 native executable.
40 val file_exists : string -> bool
44 Test if a file with the given name exists.
46 val is_directory : string -> bool
50 Returns true if the given name refers to a directory, false if it
52 refers to another kind of file. Raise Sys_error if no file exists with
53 the given name.
54 Since 3.10.0
57 val remove : string -> unit
61 Remove the given file name from the file system.
63 val rename : string -> string -> unit
67 Rename a file. rename oldpath newpath renames the file called oldpath
69 , giving it newpath as its new name, moving it between directories if
70 needed. If newpath already exists, its contents will be replaced with
71 those of oldpath . Depending on the operating system, the metadata
72 (permissions, owner, etc) of newpath can either be preserved or be
73 replaced by those of oldpath .
74 Since 4.06 concerning the "replace existing file" behavior
77 val getenv : string -> string
81 Return the value associated to a variable in the process environment.
83 Raise Not_found if the variable is unbound.
84 val getenv_opt : string -> string option
88 Return the value associated to a variable in the process environment or
90 None if the variable is unbound.
91 Since 4.05
94 val command : string -> int
98 Execute the given shell command and return its exit code.
100 val time : unit -> float
104 Return the processor time, in seconds, used by the program since the
106 beginning of execution.
107 val chdir : string -> unit
111 Change the current working directory of the process.
113 val getcwd : unit -> string
117 Return the current working directory of the process.
119 val readdir : string -> string array
123 Return the names of all files present in the given directory. Names
125 denoting the current directory and the parent directory ( . and .. in
126 Unix) are not returned. Each string in the result is a file name
127 rather than a complete path. There is no guarantee that the name
128 strings in the resulting array will appear in any specific order; they
129 are not, in particular, guaranteed to appear in alphabetical order.
130 val interactive : bool ref
134 This reference is initially set to false in standalone programs and to
136 true if the code is being executed under the interactive toplevel sys‐
137 tem ocaml .
138 val os_type : string
142 Operating system currently executing the OCaml program. One of
144 - Unix (for all Unix versions, including Linux and Mac OS X),
146 - Win32 (for MS-Windows, OCaml compiled with MSVC++ or Mingw),
148 - Cygwin (for MS-Windows, OCaml compiled with Cygwin).
150 type backend_type =
154 | Native
155 | Bytecode
156 | Other of string
157 Currently, the official distribution only supports Native and Bytecode
160 , but it can be other backends with alternative compilers, for example,
161 javascript.
162 Since 4.04.0
165 val backend_type : backend_type
169 Backend type currently executing the OCaml program.
171 Since 4.04.0
174 val unix : bool
178 True if Sys.os_type = Unix .
180 Since 4.01.0
183 val win32 : bool
187 True if Sys.os_type = Win32 .
189 Since 4.01.0
192 val cygwin : bool
196 True if Sys.os_type = Cygwin .
198 Since 4.01.0
201 val word_size : int
205 Size of one word on the machine currently executing the OCaml program,
207 in bits: 32 or 64.
208 val int_size : int
212 Size of int , in bits. It is 31 (resp. 63) when using OCaml on a 32-bit
214 (resp. 64-bit) platform. It may differ for other implementations, e.g.
215 it can be 32 bits when compiling to JavaScript.
216 Since 4.03.0
219 val big_endian : bool
223 Whether the machine currently executing the Caml program is big-endian.
225 Since 4.00.0
228 val max_string_length : int
232 Maximum length of strings and byte sequences.
234 val max_array_length : int
238 Maximum length of a normal array (i.e. any array whose elements are not
240 of type float ). The maximum length of a float array is max_floatar‐
241 ray_length if OCaml was configured with --enable-flat-float-array and
242 max_array_length if configured with --disable-flat-float-array .
243 val max_floatarray_length : int
247 Maximum length of a floatarray. This is also the maximum length of a
249 float array when OCaml is configured with --enable-flat-float-array .
250 val runtime_variant : unit -> string
254 Return the name of the runtime variant the program is running on. This
256 is normally the argument given to -runtime-variant at compile time, but
257 for byte-code it can be changed after compilation.
258 Since 4.03.0
261 val runtime_parameters : unit -> string
265 Return the value of the runtime parameters, in the same format as the
267 contents of the OCAMLRUNPARAM environment variable.
268 Since 4.03.0
271 Signal handling
276 type signal_behavior =
277 | Signal_default
278 | Signal_ignore
279 | Signal_handle of (int -> unit)
280 What to do when receiving a signal:
283 - Signal_default : take the default behavior (usually: abort the pro‐
285 gram)
286 - Signal_ignore : ignore the signal
288 - Signal_handle f : call function f , giving it the signal number as
290 argument.
291 val signal : int -> signal_behavior -> signal_behavior
296 Set the behavior of the system on receipt of a given signal. The first
298 argument is the signal number. Return the behavior previously associ‐
299 ated with the signal. If the signal number is invalid (or not available
300 on your system), an Invalid_argument exception is raised.
301 val set_signal : int -> signal_behavior -> unit
305 Same as Sys.signal but return value is ignored.
307 Signal numbers for the standard POSIX signals.
312 val sigabrt : int
313 Abnormal termination
315 val sigalrm : int
319 Timeout
321 val sigfpe : int
325 Arithmetic exception
327 val sighup : int
331 Hangup on controlling terminal
333 val sigill : int
337 Invalid hardware instruction
339 val sigint : int
343 Interactive interrupt (ctrl-C)
345 val sigkill : int
349 Termination (cannot be ignored)
351 val sigpipe : int
355 Broken pipe
357 val sigquit : int
361 Interactive termination
363 val sigsegv : int
367 Invalid memory reference
369 val sigterm : int
373 Termination
375 val sigusr1 : int
379 Application-defined signal 1
381 val sigusr2 : int
385 Application-defined signal 2
387 val sigchld : int
391 Child process terminated
393 val sigcont : int
397 Continue
399 val sigstop : int
403 Stop
405 val sigtstp : int
409 Interactive stop
411 val sigttin : int
415 Terminal read from background process
417 val sigttou : int
421 Terminal write from background process
423 val sigvtalrm : int
427 Timeout in virtual time
429 val sigprof : int
433 Profiling interrupt
435 val sigbus : int
439 Bus error
441 Since 4.03
444 val sigpoll : int
448 Pollable event
450 Since 4.03
453 val sigsys : int
457 Bad argument to routine
459 Since 4.03
462 val sigtrap : int
466 Trace/breakpoint trap
468 Since 4.03
471 val sigurg : int
475 Urgent condition on socket
477 Since 4.03
480 val sigxcpu : int
484 Timeout in cpu time
486 Since 4.03
489 val sigxfsz : int
493 File size limit exceeded
495 Since 4.03
498 exception Break
502 Exception raised on interactive interrupt if Sys.catch_break is on.
505 val catch_break : bool -> unit
509 catch_break governs whether interactive interrupt (ctrl-C) terminates
512 the program or raises the Break exception. Call catch_break true to
513 enable raising Break , and catch_break false to let the system termi‐
514 nate the program on user interrupt.
515 val ocaml_version : string
519 ocaml_version is the version of OCaml. It is a string of the form
522 major.minor[.patchlevel][+additional-info] , where major , minor , and
523 patchlevel are integers, and additional-info is an arbitrary string.
524 The [.patchlevel] and [+additional-info] parts may be absent.
525 val enable_runtime_warnings : bool -> unit
529 Control whether the OCaml runtime system can emit warnings on stderr.
531 Currently, the only supported warning is triggered when a channel cre‐
532 ated by open_* functions is finalized without being closed. Runtime
533 warnings are enabled by default.
534 Since 4.03.0
537 val runtime_warnings_enabled : unit -> bool
541 Return whether runtime warnings are currently enabled.
543 Since 4.03.0
546 Optimization
551 val opaque_identity : 'a -> 'a
552 For the purposes of optimization, opaque_identity behaves like an
554 unknown (and thus possibly side-effecting) function.
555 At runtime, opaque_identity disappears altogether.
557 A typical use of this function is to prevent pure computations from
559 being optimized away in benchmarking loops. For example: for _round =
560 1 to 100_000 do ignore (Sys.opaque_identity (my_pure_computation ()))
561 done
562 Since 4.03.0
566OCamldoc 2019-07-30 Sys(3)