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 na‐
39 tive 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.
53 Since 3.10.0
56 Raises Sys_error if no file exists with the given name.
59 val remove : string -> unit
63 Remove the given file name from the file system.
65 val rename : string -> string -> unit
69 Rename a file. rename oldpath newpath renames the file called oldpath
71 , giving it newpath as its new name, moving it between directories if
72 needed. If newpath already exists, its contents will be replaced with
73 those of oldpath . Depending on the operating system, the metadata
74 (permissions, owner, etc) of newpath can either be preserved or be re‐
75 placed by those of oldpath .
76 Since 4.06 concerning the "replace existing file" behavior
79 val getenv : string -> string
83 Return the value associated to a variable in the process environment.
85 Raises Not_found if the variable is unbound.
88 val getenv_opt : string -> string option
92 Return the value associated to a variable in the process environment or
94 None if the variable is unbound.
95 Since 4.05
98 val command : string -> int
102 Execute the given shell command and return its exit code.
104 The argument of Sys.command is generally the name of a command followed
106 by zero, one or several arguments, separated by whitespace. The given
107 argument is interpreted by a shell: either the Windows shell cmd.exe
108 for the Win32 ports of OCaml, or the POSIX shell sh for other ports.
109 It can contain shell builtin commands such as echo , and also special
110 characters such as file redirections > and < , which will be honored by
111 the shell.
112 Conversely, whitespace or special shell characters occurring in command
114 names or in their arguments must be quoted or escaped so that the shell
115 does not interpret them. The quoting rules vary between the POSIX
116 shell and the Windows shell. The Filename.quote_command performs the
117 appropriate quoting given a command name, a list of arguments, and op‐
118 tional file redirections.
119 val time : unit -> float
123 Return the processor time, in seconds, used by the program since the
125 beginning of execution.
126 val chdir : string -> unit
130 Change the current working directory of the process.
132 val mkdir : string -> int -> unit
136 Create a directory with the given permissions.
138 Since 4.12.0
141 val rmdir : string -> unit
145 Remove an empty directory.
147 Since 4.12.0
150 val getcwd : unit -> string
154 Return the current working directory of the process.
156 val readdir : string -> string array
160 Return the names of all files present in the given directory. Names
162 denoting the current directory and the parent directory ( "." and ".."
163 in Unix) are not returned. Each string in the result is a file name
164 rather than a complete path. There is no guarantee that the name
165 strings in the resulting array will appear in any specific order; they
166 are not, in particular, guaranteed to appear in alphabetical order.
167 val interactive : bool ref
171 This reference is initially set to false in standalone programs and to
173 true if the code is being executed under the interactive toplevel sys‐
174 tem ocaml .
175 val os_type : string
179 Operating system currently executing the OCaml program. One of
181 - "Unix" (for all Unix versions, including Linux and Mac OS X),
183 - "Win32" (for MS-Windows, OCaml compiled with MSVC++ or Mingw),
185 - "Cygwin" (for MS-Windows, OCaml compiled with Cygwin).
187 type backend_type =
191 | Native
192 | Bytecode
193 | Other of string
194 Currently, the official distribution only supports Native and Bytecode
197 , but it can be other backends with alternative compilers, for example,
198 javascript.
199 Since 4.04.0
202 val backend_type : backend_type
206 Backend type currently executing the OCaml program.
208 Since 4.04.0
211 val unix : bool
215 True if Sys.os_type = "Unix" .
217 Since 4.01.0
220 val win32 : bool
224 True if Sys.os_type = "Win32" .
226 Since 4.01.0
229 val cygwin : bool
233 True if Sys.os_type = "Cygwin" .
235 Since 4.01.0
238 val word_size : int
242 Size of one word on the machine currently executing the OCaml program,
244 in bits: 32 or 64.
245 val int_size : int
249 Size of int , in bits. It is 31 (resp. 63) when using OCaml on a 32-bit
251 (resp. 64-bit) platform. It may differ for other implementations, e.g.
252 it can be 32 bits when compiling to JavaScript.
253 Since 4.03.0
256 val big_endian : bool
260 Whether the machine currently executing the Caml program is big-endian.
262 Since 4.00.0
265 val max_string_length : int
269 Maximum length of strings and byte sequences.
271 val max_array_length : int
275 Maximum length of a normal array (i.e. any array whose elements are not
277 of type float ). The maximum length of a float array is max_floatar‐
278 ray_length if OCaml was configured with --enable-flat-float-array and
279 max_array_length if configured with --disable-flat-float-array .
280 val max_floatarray_length : int
284 Maximum length of a floatarray. This is also the maximum length of a
286 float array when OCaml is configured with --enable-flat-float-array .
287 val runtime_variant : unit -> string
291 Return the name of the runtime variant the program is running on. This
293 is normally the argument given to -runtime-variant at compile time, but
294 for byte-code it can be changed after compilation.
295 Since 4.03.0
298 val runtime_parameters : unit -> string
302 Return the value of the runtime parameters, in the same format as the
304 contents of the OCAMLRUNPARAM environment variable.
305 Since 4.03.0
308 Signal handling
313 type signal_behavior =
314 | Signal_default
315 | Signal_ignore
316 | Signal_handle of (int -> unit)
317 What to do when receiving a signal:
320 - Signal_default : take the default behavior (usually: abort the pro‐
322 gram)
323 - Signal_ignore : ignore the signal
325 - Signal_handle f : call function f , giving it the signal number as
327 argument.
328 val signal : int -> signal_behavior -> signal_behavior
333 Set the behavior of the system on receipt of a given signal. The first
335 argument is the signal number. Return the behavior previously associ‐
336 ated with the signal. If the signal number is invalid (or not available
337 on your system), an Invalid_argument exception is raised.
338 val set_signal : int -> signal_behavior -> unit
342 Same as Sys.signal but return value is ignored.
344 Signal numbers for the standard POSIX signals.
349 val sigabrt : int
350 Abnormal termination
352 val sigalrm : int
356 Timeout
358 val sigfpe : int
362 Arithmetic exception
364 val sighup : int
368 Hangup on controlling terminal
370 val sigill : int
374 Invalid hardware instruction
376 val sigint : int
380 Interactive interrupt (ctrl-C)
382 val sigkill : int
386 Termination (cannot be ignored)
388 val sigpipe : int
392 Broken pipe
394 val sigquit : int
398 Interactive termination
400 val sigsegv : int
404 Invalid memory reference
406 val sigterm : int
410 Termination
412 val sigusr1 : int
416 Application-defined signal 1
418 val sigusr2 : int
422 Application-defined signal 2
424 val sigchld : int
428 Child process terminated
430 val sigcont : int
434 Continue
436 val sigstop : int
440 Stop
442 val sigtstp : int
446 Interactive stop
448 val sigttin : int
452 Terminal read from background process
454 val sigttou : int
458 Terminal write from background process
460 val sigvtalrm : int
464 Timeout in virtual time
466 val sigprof : int
470 Profiling interrupt
472 val sigbus : int
476 Bus error
478 Since 4.03
481 val sigpoll : int
485 Pollable event
487 Since 4.03
490 val sigsys : int
494 Bad argument to routine
496 Since 4.03
499 val sigtrap : int
503 Trace/breakpoint trap
505 Since 4.03
508 val sigurg : int
512 Urgent condition on socket
514 Since 4.03
517 val sigxcpu : int
521 Timeout in cpu time
523 Since 4.03
526 val sigxfsz : int
530 File size limit exceeded
532 Since 4.03
535 exception Break
539 Exception raised on interactive interrupt if Sys.catch_break is on.
542 val catch_break : bool -> unit
546 catch_break governs whether interactive interrupt (ctrl-C) terminates
549 the program or raises the Break exception. Call catch_break true to
550 enable raising Break , and catch_break false to let the system termi‐
551 nate the program on user interrupt.
552 val ocaml_version : string
556 ocaml_version is the version of OCaml. It is a string of the form "ma‐
559 jor.minor[.patchlevel][(+|~)additional-info]" , where major , minor ,
560 and patchlevel are integers, and additional-info is an arbitrary
561 string. The [.patchlevel] part was absent before version 3.08.0 and
562 became mandatory from 3.08.0 onwards. The [(+|~)additional-info] part
563 may be absent.
564 val development_version : bool
568 true if this is a development version, false otherwise.
571 Since 4.14.0
574 type extra_prefix =
577 | Plus
578 | Tilde
579 type extra_info = extra_prefix * string
584 type ocaml_release_info = {
589 major : int ;
590 minor : int ;
591 patchlevel : int ;
592 extra : extra_info option ;
593 }
594 val ocaml_release : ocaml_release_info
600 val enable_runtime_warnings : bool -> unit
605 Control whether the OCaml runtime system can emit warnings on stderr.
607 Currently, the only supported warning is triggered when a channel cre‐
608 ated by open_* functions is finalized without being closed. Runtime
609 warnings are disabled by default.
610 Since 4.03.0
613 val runtime_warnings_enabled : unit -> bool
617 Return whether runtime warnings are currently enabled.
619 Since 4.03.0
622 Optimization
627 val opaque_identity : 'a -> 'a
628 For the purposes of optimization, opaque_identity behaves like an un‐
630 known (and thus possibly side-effecting) function.
631 At runtime, opaque_identity disappears altogether.
633 A typical use of this function is to prevent pure computations from be‐
635 ing optimized away in benchmarking loops. For example:
636 for _round = 1 to 100_000 do
637 ignore (Sys.opaque_identity (my_pure_computation ()))
638 done
639 Since 4.03.0
643 module Immediate64 : sig end
646OCamldoc 2022-07-22 Sys(3)