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 Pervasives.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. The maximum length of a float array
240 is max_array_length/2 on 32-bit machines and max_array_length on 64-bit
241 machines.
242 val runtime_variant : unit -> string
246 Return the name of the runtime variant the program is running on. This
248 is normally the argument given to -runtime-variant at compile time, but
249 for byte-code it can be changed after compilation.
250 Since 4.03.0
253 val runtime_parameters : unit -> string
257 Return the value of the runtime parameters, in the same format as the
259 contents of the OCAMLRUNPARAM environment variable.
260 Since 4.03.0
263 === Signal handling ===
268 type signal_behavior =
271 | Signal_default
272 | Signal_ignore
273 | Signal_handle of (int -> unit)
274 What to do when receiving a signal:
277 - Signal_default : take the default behavior (usually: abort the pro‐
279 gram)
280 - Signal_ignore : ignore the signal
282 - Signal_handle f : call function f , giving it the signal number as
284 argument.
285 val signal : int -> signal_behavior -> signal_behavior
290 Set the behavior of the system on receipt of a given signal. The first
292 argument is the signal number. Return the behavior previously associ‐
293 ated with the signal. If the signal number is invalid (or not available
294 on your system), an Invalid_argument exception is raised.
295 val set_signal : int -> signal_behavior -> unit
299 Same as Sys.signal but return value is ignored.
301 === Signal numbers for the standard POSIX signals. ===
306 val sigabrt : int
309 Abnormal termination
311 val sigalrm : int
315 Timeout
317 val sigfpe : int
321 Arithmetic exception
323 val sighup : int
327 Hangup on controlling terminal
329 val sigill : int
333 Invalid hardware instruction
335 val sigint : int
339 Interactive interrupt (ctrl-C)
341 val sigkill : int
345 Termination (cannot be ignored)
347 val sigpipe : int
351 Broken pipe
353 val sigquit : int
357 Interactive termination
359 val sigsegv : int
363 Invalid memory reference
365 val sigterm : int
369 Termination
371 val sigusr1 : int
375 Application-defined signal 1
377 val sigusr2 : int
381 Application-defined signal 2
383 val sigchld : int
387 Child process terminated
389 val sigcont : int
393 Continue
395 val sigstop : int
399 Stop
401 val sigtstp : int
405 Interactive stop
407 val sigttin : int
411 Terminal read from background process
413 val sigttou : int
417 Terminal write from background process
419 val sigvtalrm : int
423 Timeout in virtual time
425 val sigprof : int
429 Profiling interrupt
431 val sigbus : int
435 Bus error
437 Since 4.03
440 val sigpoll : int
444 Pollable event
446 Since 4.03
449 val sigsys : int
453 Bad argument to routine
455 Since 4.03
458 val sigtrap : int
462 Trace/breakpoint trap
464 Since 4.03
467 val sigurg : int
471 Urgent condition on socket
473 Since 4.03
476 val sigxcpu : int
480 Timeout in cpu time
482 Since 4.03
485 val sigxfsz : int
489 File size limit exceeded
491 Since 4.03
494 exception Break
498 Exception raised on interactive interrupt if Sys.catch_break is on.
501 val catch_break : bool -> unit
505 catch_break governs whether interactive interrupt (ctrl-C) terminates
508 the program or raises the Break exception. Call catch_break true to
509 enable raising Break , and catch_break false to let the system termi‐
510 nate the program on user interrupt.
511 val ocaml_version : string
515 ocaml_version is the version of OCaml. It is a string of the form
518 major.minor[.patchlevel][+additional-info] , where major , minor , and
519 patchlevel are integers, and additional-info is an arbitrary string.
520 The [.patchlevel] and [+additional-info] parts may be absent.
521 val enable_runtime_warnings : bool -> unit
525 Control whether the OCaml runtime system can emit warnings on stderr.
527 Currently, the only supported warning is triggered when a channel cre‐
528 ated by open_* functions is finalized without being closed. Runtime
529 warnings are enabled by default.
530 Since 4.03.0
533 val runtime_warnings_enabled : unit -> bool
537 Return whether runtime warnings are currently enabled.
539 Since 4.03.0
542 === Optimization ===
547 val opaque_identity : 'a -> 'a
550 For the purposes of optimization, opaque_identity behaves like an
552 unknown (and thus possibly side-effecting) function.
553 At runtime, opaque_identity disappears altogether.
555 A typical use of this function is to prevent pure computations from
557 being optimized away in benchmarking loops. For example: for _round =
558 1 to 100_000 do ignore (Sys.opaque_identity (my_pure_computation ()))
559 done
560 Since 4.03.0
564OCamldoc 2019-02-02 Sys(3)