UnixLabels
Interface to the Unix system.
To use the labeled version of this module, add module Unix
=
UnixLabels
in your implementation.
Note: all the functions of this module (except error_message
and handle_unix_error
) are liable to raise the Unix_error
exception whenever the underlying system call signals an error.
type error = Unix.error =
| E2BIG
Argument list too long
*)| EACCES
Permission denied
*)| EAGAIN
Resource temporarily unavailable; try again
*)| EBADF
Bad file descriptor
*)| EBUSY
Resource unavailable
*)| ECHILD
No child process
*)| EDEADLK
Resource deadlock would occur
*)| EDOM
Domain error for math functions, etc.
*)| EEXIST
File exists
*)| EFAULT
Bad address
*)| EFBIG
File too large
*)| EINTR
Function interrupted by signal
*)| EINVAL
Invalid argument
*)| EIO
Hardware I/O error
*)| EISDIR
Is a directory
*)| EMFILE
Too many open files by the process
*)| EMLINK
Too many links
*)| ENAMETOOLONG
Filename too long
*)| ENFILE
Too many open files in the system
*)| ENODEV
No such device
*)| ENOENT
No such file or directory
*)| ENOEXEC
Not an executable file
*)| ENOLCK
No locks available
*)| ENOMEM
Not enough memory
*)| ENOSPC
No space left on device
*)| ENOSYS
Function not supported
*)| ENOTDIR
Not a directory
*)| ENOTEMPTY
Directory not empty
*)| ENOTTY
Inappropriate I/O control operation
*)| ENXIO
No such device or address
*)| EPERM
Operation not permitted
*)| EPIPE
Broken pipe
*)| ERANGE
Result too large
*)| EROFS
Read-only file system
*)| ESPIPE
Invalid seek e.g. on a pipe
*)| ESRCH
No such process
*)| EXDEV
Invalid link
*)| EWOULDBLOCK
Operation would block
*)| EINPROGRESS
Operation now in progress
*)| EALREADY
Operation already in progress
*)| ENOTSOCK
Socket operation on non-socket
*)| EDESTADDRREQ
Destination address required
*)| EMSGSIZE
Message too long
*)| EPROTOTYPE
Protocol wrong type for socket
*)| ENOPROTOOPT
Protocol not available
*)| EPROTONOSUPPORT
Protocol not supported
*)| ESOCKTNOSUPPORT
Socket type not supported
*)| EOPNOTSUPP
Operation not supported on socket
*)| EPFNOSUPPORT
Protocol family not supported
*)| EAFNOSUPPORT
Address family not supported by protocol family
*)| EADDRINUSE
Address already in use
*)| EADDRNOTAVAIL
Can't assign requested address
*)| ENETDOWN
Network is down
*)| ENETUNREACH
Network is unreachable
*)| ENETRESET
Network dropped connection on reset
*)| ECONNABORTED
Software caused connection abort
*)| ECONNRESET
Connection reset by peer
*)| ENOBUFS
No buffer space available
*)| EISCONN
Socket is already connected
*)| ENOTCONN
Socket is not connected
*)| ESHUTDOWN
Can't send after socket shutdown
*)| ETOOMANYREFS
Too many references: can't splice
*)| ETIMEDOUT
Connection timed out
*)| ECONNREFUSED
Connection refused
*)| EHOSTDOWN
Host is down
*)| EHOSTUNREACH
No route to host
*)| ELOOP
Too many levels of symbolic links
*)| EOVERFLOW
File size or position not representable
*)| EUNKNOWNERR of int
Unknown error
*)The type of error codes. Errors defined in the POSIX standard and additional errors from UNIX98 and BSD. All other errors are mapped to EUNKNOWNERR.
exception Unix_error of error * string * string
Raised by the system calls below when an error is encountered. The first component is the error code; the second component is the function name; the third component is the string parameter to the function, if it has one, or the empty string otherwise.
UnixLabels.Unix_error
and Unix.Unix_error
are the same, and catching one will catch the other.
val error_message : error -> string
Return a string describing the given error code.
handle_unix_error f x
applies f
to x
and returns the result. If the exception Unix_error
is raised, it prints a message describing the error and exits with code 2.
Return the process environment, as an array of strings with the format ``variable=value''. The returned array is empty if the process has special privileges.
Return the process environment, as an array of strings with the format ``variable=value''. Unlike environment
, this function returns a populated array even if the process has special privileges. See the documentation for unsafe_getenv
for more details.
Return the value associated to a variable in the process environment, unless the process has special privileges.
Return the value associated to a variable in the process environment.
Unlike getenv
, this function returns the value even if the process has special privileges. It is considered unsafe because the programmer of a setuid or setgid program must be careful to avoid using maliciously crafted environment variables in the search path for executables, the locations for temporary files or logs, and the like.
putenv name value
sets the value associated to a variable in the process environment. name
is the name of the environment variable, and value
its new associated value.
type process_status = Unix.process_status =
The termination status of a process. See module Sys
for the definitions of the standard signal numbers. Note that they are not the numbers used by the OS.
On Windows: only WEXITED
is used (as there are no inter-process signals) but with specific return codes to indicate special termination causes. Look for NTSTATUS
values in the Windows documentation to decode such error return codes. In particular, STATUS_ACCESS_VIOLATION
error code is the 32-bit 0xC0000005
: as Int32.of_int 0xC0000005
is -1073741819
, WEXITED -1073741819
is the Windows equivalent of WSIGNALED Sys.sigsegv
.
type wait_flag = Unix.wait_flag =
Flags for waitpid
.
execv ~prog ~args
execute the program in file prog
, with the arguments args
, and the current process environment. These execv*
functions never return: on success, the current program is replaced by the new one.
On Windows: the CRT simply spawns a new process and exits the current one. This will have unwanted consequences if e.g. another process is waiting on the current one. Using create_process
or one of the open_process_*
functions instead is recommended.
Same as execv
, except that the third argument provides the environment to the program executed.
Same as execv
, except that the program is searched in the path.
Same as execve
, except that the program is searched in the path.
Fork a new process. The returned integer is 0 for the child process, the pid of the child process for the parent process.
val wait : unit -> int * process_status
Wait until one of the children processes die, and return its pid and termination status.
val waitpid : mode:wait_flag list -> int -> int * process_status
Same as wait
, but waits for the child process whose pid is given. A pid of -1
means wait for any child. A pid of 0
means wait for any child in the same process group as the current process. Negative pid arguments represent process groups. The list of options indicates whether waitpid
should return immediately without waiting, and whether it should report stopped children.
On Windows: can only wait for a given PID, not any child process.
val system : string -> process_status
Execute the given command, wait until it terminates, and return its termination status. The string is interpreted by the shell /bin/sh
(or the command interpreter cmd.exe
on Windows) and therefore can contain redirections, quotes, variables, etc. To properly quote whitespace and shell special characters occurring in file names or command arguments, the use of Filename.quote_command
is recommended. The result WEXITED 127
indicates that the shell couldn't be executed.
Terminate the calling process immediately, returning the given status code to the operating system: usually 0 to indicate no errors, and a small positive integer to indicate failure. Unlike Stdlib.exit
, Unix._exit
performs no finalization whatsoever: functions registered with Stdlib.at_exit
are not called, input/output channels are not flushed, and the C run-time system is not finalized either.
The typical use of Unix._exit
is after a Unix.fork
operation, when the child process runs into a fatal error and must exit. In this case, it is preferable to not perform any finalization action in the child process, as these actions could interfere with similar actions performed by the parent process. For example, output channels should not be flushed by the child process, as the parent process may flush them again later, resulting in duplicate output.
Change the process priority. The integer argument is added to the ``nice'' value. (Higher values of the ``nice'' value mean lower priorities.) Return the new nice value.
type file_descr = Unix.file_descr
The abstract type of file descriptors.
val stdin : file_descr
File descriptor for standard input.
val stdout : file_descr
File descriptor for standard output.
val stderr : file_descr
File descriptor for standard error.
type open_flag = Unix.open_flag =
| O_RDONLY
Open for reading
*)| O_WRONLY
Open for writing
*)| O_RDWR
Open for reading and writing
*)| O_NONBLOCK
Open in non-blocking mode
*)| O_APPEND
Open for append
*)| O_CREAT
Create if nonexistent
*)| O_TRUNC
Truncate to 0 length if existing
*)| O_EXCL
Fail if existing
*)| O_NOCTTY
Don't make this dev a controlling tty
*)| O_DSYNC
Writes complete as `Synchronised I/O data integrity completion'
*)| O_SYNC
Writes complete as `Synchronised I/O file integrity completion'
*)| O_RSYNC
Reads complete as writes (depending on O_SYNC/O_DSYNC)
*)| O_SHARE_DELETE
Windows only: allow the file to be deleted while still open
*)| O_CLOEXEC
Set the close-on-exec flag on the descriptor returned by openfile
. See set_close_on_exec
for more information.
| O_KEEPEXEC
Clear the close-on-exec flag. This is currently the default.
*)The flags to openfile
.
The type of file access rights, e.g. 0o640
is read and write for user, read for group, none for others
val openfile : string -> mode:open_flag list -> perm:file_perm -> file_descr
Open the named file with the given flags. Third argument is the permissions to give to the file if it is created (see umask
). Return a file descriptor on the named file.
val close : file_descr -> unit
Close a file descriptor.
val fsync : file_descr -> unit
Flush file buffers to disk.
val read : file_descr -> buf:bytes -> pos:int -> len:int -> int
read fd ~buf ~pos ~len
reads len
bytes from descriptor fd
, storing them in byte sequence buf
, starting at position pos
in buf
. Return the number of bytes actually read.
val write : file_descr -> buf:bytes -> pos:int -> len:int -> int
write fd ~buf ~pos ~len
writes len
bytes to descriptor fd
, taking them from byte sequence buf
, starting at position pos
in buff
. Return the number of bytes actually written. write
repeats the writing operation until all bytes have been written or an error occurs.
val single_write : file_descr -> buf:bytes -> pos:int -> len:int -> int
Same as write
, but attempts to write only once. Thus, if an error occurs, single_write
guarantees that no data has been written.
val write_substring : file_descr -> buf:string -> pos:int -> len:int -> int
Same as write
, but take the data from a string instead of a byte sequence.
val single_write_substring :
file_descr ->
buf:string ->
pos:int ->
len:int ->
int
Same as single_write
, but take the data from a string instead of a byte sequence.
val in_channel_of_descr : file_descr -> in_channel
Create an input channel reading from the given descriptor. The channel is initially in binary mode; use set_binary_mode_in ic false
if text mode is desired. Text mode is supported only if the descriptor refers to a file or pipe, but is not supported if it refers to a socket.
On Windows: Stdlib.set_binary_mode_in
always fails on channels created with this function.
Beware that input channels are buffered, so more characters may have been read from the descriptor than those accessed using channel functions. Channels also keep a copy of the current position in the file.
Closing the channel ic
returned by in_channel_of_descr fd
using close_in ic
also closes the underlying descriptor fd
. It is incorrect to close both the channel ic
and the descriptor fd
.
If several channels are created on the same descriptor, one of the channels must be closed, but not the others. Consider for example a descriptor s
connected to a socket and two channels ic = in_channel_of_descr s
and oc = out_channel_of_descr s
. The recommended closing protocol is to perform close_out oc
, which flushes buffered output to the socket then closes the socket. The ic
channel must not be closed and will be collected by the GC eventually.
val out_channel_of_descr : file_descr -> out_channel
Create an output channel writing on the given descriptor. The channel is initially in binary mode; use set_binary_mode_out oc false
if text mode is desired. Text mode is supported only if the descriptor refers to a file or pipe, but is not supported if it refers to a socket.
On Windows: Stdlib.set_binary_mode_out
always fails on channels created with this function.
Beware that output channels are buffered, so you may have to call Stdlib.flush
to ensure that all data has been sent to the descriptor. Channels also keep a copy of the current position in the file.
Closing the channel oc
returned by out_channel_of_descr fd
using close_out oc
also closes the underlying descriptor fd
. It is incorrect to close both the channel ic
and the descriptor fd
.
See Unix.in_channel_of_descr
for a discussion of the closing protocol when several channels are created on the same descriptor.
val descr_of_in_channel : in_channel -> file_descr
Return the descriptor corresponding to an input channel.
val descr_of_out_channel : out_channel -> file_descr
Return the descriptor corresponding to an output channel.
type seek_command = Unix.seek_command =
Positioning modes for lseek
.
val lseek : file_descr -> int -> mode:seek_command -> int
Set the current position for a file descriptor, and return the resulting offset (from the beginning of the file).
val ftruncate : file_descr -> len:int -> unit
Truncates the file corresponding to the given descriptor to the given size.
type file_kind = Unix.file_kind =
type stats = Unix.stats = {
st_dev : int;
Device number
*)st_ino : int;
Inode number
*)st_kind : file_kind;
Kind of the file
*)st_perm : file_perm;
Access rights
*)st_nlink : int;
Number of links
*)st_uid : int;
User id of the owner
*)st_gid : int;
Group ID of the file's group
*)st_rdev : int;
Device ID (if special file)
*)st_size : int;
Size in bytes
*)st_atime : float;
Last access time
*)st_mtime : float;
Last modification time
*)st_ctime : float;
Last status change time
*)}
The information returned by the stat
calls.
val stat : string -> stats
Return the information for the named file.
val lstat : string -> stats
Same as stat
, but in case the file is a symbolic link, return the information for the link itself.
val fstat : file_descr -> stats
Return the information for the file associated with the given descriptor.
val isatty : file_descr -> bool
Return true
if the given file descriptor refers to a terminal or console window, false
otherwise.
module LargeFile : sig ... end
File operations on large files. This sub-module provides 64-bit variants of the functions lseek
(for positioning a file descriptor), truncate
and ftruncate
(for changing the size of a file), and stat
, lstat
and fstat
(for obtaining information on files). These alternate functions represent positions and sizes by 64-bit integers (type int64
) instead of regular integers (type int
), thus allowing operating on files whose sizes are greater than max_int
.
val map_file :
file_descr ->
?pos:int64 ->
kind:('a, 'b) Stdlib.Bigarray.kind ->
layout:'c Stdlib.Bigarray.layout ->
shared:bool ->
dims:int array ->
('a, 'b, 'c) Stdlib.Bigarray.Genarray.t
Memory mapping of a file as a Bigarray. map_file fd ~kind ~layout ~shared ~dims
returns a Bigarray of kind kind
, layout layout
, and dimensions as specified in dims
. The data contained in this Bigarray are the contents of the file referred to by the file descriptor fd
(as opened previously with openfile
, for example). The optional pos
parameter is the byte offset in the file of the data being mapped; it defaults to 0 (map from the beginning of the file).
If shared
is true
, all modifications performed on the array are reflected in the file. This requires that fd
be opened with write permissions. If shared
is false
, modifications performed on the array are done in memory only, using copy-on-write of the modified pages; the underlying file is not affected.
map_file
is much more efficient than reading the whole file in a Bigarray, modifying that Bigarray, and writing it afterwards.
To adjust automatically the dimensions of the Bigarray to the actual size of the file, the major dimension (that is, the first dimension for an array with C layout, and the last dimension for an array with Fortran layout) can be given as -1
. map_file
then determines the major dimension from the size of the file. The file must contain an integral number of sub-arrays as determined by the non-major dimensions, otherwise Failure
is raised.
If all dimensions of the Bigarray are given, the file size is matched against the size of the Bigarray. If the file is larger than the Bigarray, only the initial portion of the file is mapped to the Bigarray. If the file is smaller than the big array, the file is automatically grown to the size of the Bigarray. This requires write permissions on fd
.
Array accesses are bounds-checked, but the bounds are determined by the initial call to map_file
. Therefore, you should make sure no other process modifies the mapped file while you're accessing it, or a SIGBUS signal may be raised. This happens, for instance, if the file is shrunk.
Invalid_argument
or Failure
may be raised in cases where argument validation fails.
Removes the named file.
If the named file is a directory, raises:
EPERM
on POSIX compliant systemEISDIR
on Linux >= 2.1.132EACCESS
on Windowsrename ~src ~dst
changes the name of a file from src
to dst
, moving it between directories if needed. If dst
already exists, its contents will be replaced with those of src
. Depending on the operating system, the metadata (permissions, owner, etc) of dst
can either be preserved or be replaced by those of src
.
link ?follow ~src ~dst
creates a hard link named dst
to the file named src
.
realpath p
is an absolute pathname for p
obtained by resolving all extra /
characters, relative path segments and symbolic links.
type access_permission = Unix.access_permission =
Flags for the access
call.
val chmod : string -> perm:file_perm -> unit
Change the permissions of the named file.
val fchmod : file_descr -> perm:file_perm -> unit
Change the permissions of an opened file.
Change the owner uid and owner gid of the named file.
val fchown : file_descr -> uid:int -> gid:int -> unit
Change the owner uid and owner gid of an opened file.
Set the process's file mode creation mask, and return the previous mask.
val access : string -> perm:access_permission list -> unit
Check that the process has the given permissions over the named file.
On Windows: execute permission X_OK
cannot be tested, just tests for read permission instead.
val dup : ?cloexec:bool -> file_descr -> file_descr
Return a new file descriptor referencing the same file as the given descriptor. See set_close_on_exec
for documentation on the cloexec
optional argument.
val dup2 : ?cloexec:bool -> src:file_descr -> dst:file_descr -> unit
dup2 ~src ~dst
duplicates src
to dst
, closing dst
if already opened. See set_close_on_exec
for documentation on the cloexec
optional argument.
val set_nonblock : file_descr -> unit
Set the ``non-blocking'' flag on the given descriptor. When the non-blocking flag is set, reading on a descriptor on which there is temporarily no data available raises the EAGAIN
or EWOULDBLOCK
error instead of blocking; writing on a descriptor on which there is temporarily no room for writing also raises EAGAIN
or EWOULDBLOCK
.
val clear_nonblock : file_descr -> unit
Clear the ``non-blocking'' flag on the given descriptor. See set_nonblock
.
val set_close_on_exec : file_descr -> unit
Set the ``close-on-exec'' flag on the given descriptor. A descriptor with the close-on-exec flag is automatically closed when the current process starts another program with one of the exec
, create_process
and open_process
functions.
It is often a security hole to leak file descriptors opened on, say, a private file to an external program: the program, then, gets access to the private file and can do bad things with it. Hence, it is highly recommended to set all file descriptors ``close-on-exec'', except in the very few cases where a file descriptor actually needs to be transmitted to another program.
The best way to set a file descriptor ``close-on-exec'' is to create it in this state. To this end, the openfile
function has O_CLOEXEC
and O_KEEPEXEC
flags to enforce ``close-on-exec'' mode or ``keep-on-exec'' mode, respectively. All other operations in the Unix module that create file descriptors have an optional argument ?cloexec:bool
to indicate whether the file descriptor should be created in ``close-on-exec'' mode (by writing ~cloexec:true
) or in ``keep-on-exec'' mode (by writing ~cloexec:false
). For historical reasons, the default file descriptor creation mode is ``keep-on-exec'', if no cloexec
optional argument is given. This is not a safe default, hence it is highly recommended to pass explicit cloexec
arguments to operations that create file descriptors.
The cloexec
optional arguments and the O_KEEPEXEC
flag were introduced in OCaml 4.05. Earlier, the common practice was to create file descriptors in the default, ``keep-on-exec'' mode, then call set_close_on_exec
on those freshly-created file descriptors. This is not as safe as creating the file descriptor in ``close-on-exec'' mode because, in multithreaded programs, a window of vulnerability exists between the time when the file descriptor is created and the time set_close_on_exec
completes. If another thread spawns another program during this window, the descriptor will leak, as it is still in the ``keep-on-exec'' mode.
Regarding the atomicity guarantees given by ~cloexec:true
or by the use of the O_CLOEXEC
flag: on all platforms it is guaranteed that a concurrently-executing Caml thread cannot leak the descriptor by starting a new process. On Linux, this guarantee extends to concurrently-executing C threads. As of Feb 2017, other operating systems lack the necessary system calls and still expose a window of vulnerability during which a C thread can see the newly-created file descriptor in ``keep-on-exec'' mode.
val clear_close_on_exec : file_descr -> unit
Clear the ``close-on-exec'' flag on the given descriptor. See set_close_on_exec
.
val mkdir : string -> perm:file_perm -> unit
Create a directory with the given permissions (see umask
).
type dir_handle = Unix.dir_handle
The type of descriptors over opened directories.
val opendir : string -> dir_handle
Open a descriptor on a directory
val readdir : dir_handle -> string
Return the next entry in a directory.
val rewinddir : dir_handle -> unit
Reposition the descriptor to the beginning of the directory
val closedir : dir_handle -> unit
Close a directory descriptor.
val pipe : ?cloexec:bool -> unit -> file_descr * file_descr
Create a pipe. The first component of the result is opened for reading, that's the exit to the pipe. The second component is opened for writing, that's the entrance to the pipe. See set_close_on_exec
for documentation on the cloexec
optional argument.
val mkfifo : string -> perm:file_perm -> unit
Create a named pipe with the given permissions (see umask
).
val create_process :
prog:string ->
args:string array ->
stdin:file_descr ->
stdout:file_descr ->
stderr:file_descr ->
int
create_process ~prog ~args ~stdin ~stdout ~stderr
creates a new process that executes the program in file prog
, with arguments args
. The pid of the new process is returned immediately; the new process executes concurrently with the current process. The standard input and outputs of the new process are connected to the descriptors stdin
, stdout
and stderr
. Passing e.g. Unix.stdout
for stdout
prevents the redirection and causes the new process to have the same standard output as the current process. The executable file prog
is searched in the path. The new process has the same environment as the current process.
val create_process_env :
prog:string ->
args:string array ->
env:string array ->
stdin:file_descr ->
stdout:file_descr ->
stderr:file_descr ->
int
create_process_env ~prog ~args ~env ~stdin ~stdout ~stderr
works as create_process
, except that the extra argument env
specifies the environment passed to the program.
val open_process_in : string -> in_channel
High-level pipe and process management. This function runs the given command in parallel with the program. The standard output of the command is redirected to a pipe, which can be read via the returned input channel. The command is interpreted by the shell /bin/sh
(or cmd.exe
on Windows), cf. system
. The Filename.quote_command
function can be used to quote the command and its arguments as appropriate for the shell being used. If the command does not need to be run through the shell, open_process_args_in
can be used as a more robust and more efficient alternative to open_process_in
.
val open_process_out : string -> out_channel
Same as open_process_in
, but redirect the standard input of the command to a pipe. Data written to the returned output channel is sent to the standard input of the command. Warning: writes on output channels are buffered, hence be careful to call Stdlib.flush
at the right times to ensure correct synchronization. If the command does not need to be run through the shell, open_process_args_out
can be used instead of open_process_out
.
val open_process : string -> in_channel * out_channel
Same as open_process_out
, but redirects both the standard input and standard output of the command to pipes connected to the two returned channels. The input channel is connected to the output of the command, and the output channel to the input of the command. If the command does not need to be run through the shell, open_process_args
can be used instead of open_process
.
val open_process_full :
string ->
env:string array ->
in_channel * out_channel * in_channel
Similar to open_process
, but the second argument specifies the environment passed to the command. The result is a triple of channels connected respectively to the standard output, standard input, and standard error of the command. If the command does not need to be run through the shell, open_process_args_full
can be used instead of open_process_full
.
val open_process_args : string -> string array -> in_channel * out_channel
open_process_args prog args
runs the program prog
with arguments args
. Note that the first argument is by convention the filename of the program being executed, just like Sys.argv.(0)
. The new process executes concurrently with the current process. The standard input and output of the new process are redirected to pipes, which can be respectively read and written via the returned channels. The input channel is connected to the output of the program, and the output channel to the input of the program.
Warning: writes on output channels are buffered, hence be careful to call Stdlib.flush
at the right times to ensure correct synchronization.
The executable file prog
is searched for in the path. This behaviour changed in 4.12; previously prog
was looked up only in the current directory.
The new process has the same environment as the current process.
val open_process_args_in : string -> string array -> in_channel
Same as open_process_args
, but redirects only the standard output of the new process.
val open_process_args_out : string -> string array -> out_channel
Same as open_process_args
, but redirects only the standard input of the new process.
val open_process_args_full :
string ->
string array ->
string array ->
in_channel * out_channel * in_channel
Similar to open_process_args
, but the third argument specifies the environment passed to the new process. The result is a triple of channels connected respectively to the standard output, standard input, and standard error of the program.
val process_in_pid : in_channel -> int
Return the pid of a process opened via open_process_in
or open_process_args_in
.
val process_out_pid : out_channel -> int
Return the pid of a process opened via open_process_out
or open_process_args_out
.
val process_pid : (in_channel * out_channel) -> int
Return the pid of a process opened via open_process
or open_process_args
.
val process_full_pid : (in_channel * out_channel * in_channel) -> int
Return the pid of a process opened via open_process_full
or open_process_args_full
.
val close_process_in : in_channel -> process_status
Close channels opened by open_process_in
, wait for the associated command to terminate, and return its termination status.
val close_process_out : out_channel -> process_status
Close channels opened by open_process_out
, wait for the associated command to terminate, and return its termination status.
val close_process : (in_channel * out_channel) -> process_status
Close channels opened by open_process
, wait for the associated command to terminate, and return its termination status.
val close_process_full :
(in_channel * out_channel * in_channel) ->
process_status
Close channels opened by open_process_full
, wait for the associated command to terminate, and return its termination status.
symlink ?to_dir ~src ~dst
creates the file dst
as a symbolic link to the file src
. On Windows, ~to_dir
indicates if the symbolic link points to a directory or a file; if omitted, symlink
examines src
using stat
and picks appropriately, if src
does not exist then false
is assumed (for this reason, it is recommended that the ~to_dir
parameter be specified in new code). On Unix, ~to_dir
is ignored.
Windows symbolic links are available in Windows Vista onwards. There are some important differences between Windows symlinks and their POSIX counterparts.
Windows symbolic links come in two flavours: directory and regular, which designate whether the symbolic link points to a directory or a file. The type must be correct - a directory symlink which actually points to a file cannot be selected with chdir and a file symlink which actually points to a directory cannot be read or written (note that Cygwin's emulation layer ignores this distinction).
When symbolic links are created to existing targets, this distinction doesn't matter and symlink
will automatically create the correct kind of symbolic link. The distinction matters when a symbolic link is created to a non-existent target.
The other caveat is that by default symbolic links are a privileged operation. Administrators will always need to be running elevated (or with UAC disabled) and by default normal user accounts need to be granted the SeCreateSymbolicLinkPrivilege via Local Security Policy (secpol.msc) or via Active Directory.
has_symlink
can be used to check that a process is able to create symbolic links.
Returns true
if the user is able to create symbolic links. On Windows, this indicates that the user not only has the SeCreateSymbolicLinkPrivilege but is also running elevated, if necessary. On other platforms, this is simply indicates that the symlink system call is available.
val select :
read:file_descr list ->
write:file_descr list ->
except:file_descr list ->
timeout:float ->
file_descr list * file_descr list * file_descr list
Wait until some input/output operations become possible on some channels. The three list arguments are, respectively, a set of descriptors to check for reading (first argument), for writing (second argument), or for exceptional conditions (third argument). The fourth argument is the maximal timeout, in seconds; a negative fourth argument means no timeout (unbounded wait). The result is composed of three sets of descriptors: those ready for reading (first component), ready for writing (second component), and over which an exceptional condition is pending (third component).
type lock_command = Unix.lock_command =
| F_ULOCK
Unlock a region
*)| F_LOCK
Lock a region for writing, and block if already locked
*)| F_TLOCK
Lock a region for writing, or fail if already locked
*)| F_TEST
Test a region for other process locks
*)| F_RLOCK
Lock a region for reading, and block if already locked
*)| F_TRLOCK
Lock a region for reading, or fail if already locked
*)Commands for lockf
.
val lockf : file_descr -> mode:lock_command -> len:int -> unit
lockf fd ~mode ~len
puts a lock on a region of the file opened as fd
. The region starts at the current read/write position for fd
(as set by lseek
), and extends len
bytes forward if len
is positive, len
bytes backwards if len
is negative, or to the end of the file if len
is zero. A write lock prevents any other process from acquiring a read or write lock on the region. A read lock prevents any other process from acquiring a write lock on the region, but lets other processes acquire read locks on it.
The F_LOCK
and F_TLOCK
commands attempts to put a write lock on the specified region. The F_RLOCK
and F_TRLOCK
commands attempts to put a read lock on the specified region. If one or several locks put by another process prevent the current process from acquiring the lock, F_LOCK
and F_RLOCK
block until these locks are removed, while F_TLOCK
and F_TRLOCK
fail immediately with an exception. The F_ULOCK
removes whatever locks the current process has on the specified region. Finally, the F_TEST
command tests whether a write lock can be acquired on the specified region, without actually putting a lock. It returns immediately if successful, or fails otherwise.
What happens when a process tries to lock a region of a file that is already locked by the same process depends on the OS. On POSIX-compliant systems, the second lock operation succeeds and may "promote" the older lock from read lock to write lock. On Windows, the second lock operation will block or fail.
Note: installation of signal handlers is performed via the functions Sys.signal
and Sys.set_signal
.
kill ~pid ~signal
sends signal number signal
to the process with id pid
.
On Windows: only the Sys.sigkill
signal is emulated.
val sigprocmask : mode:sigprocmask_command -> int list -> int list
sigprocmask ~mode sigs
changes the set of blocked signals. If mode
is SIG_SETMASK
, blocked signals are set to those in the list sigs
. If mode
is SIG_BLOCK
, the signals in sigs
are added to the set of blocked signals. If mode
is SIG_UNBLOCK
, the signals in sigs
are removed from the set of blocked signals. sigprocmask
returns the set of previously blocked signals.
When the systhreads version of the Thread
module is loaded, this function redirects to Thread.sigmask
. I.e., sigprocmask
only changes the mask of the current thread.
sigsuspend sigs
atomically sets the blocked signals to sigs
and waits for a non-ignored, non-blocked signal to be delivered. On return, the blocked signals are reset to their initial value.
type process_times = Unix.process_times = {
tms_utime : float;
User time for the process
*)tms_stime : float;
System time for the process
*)tms_cutime : float;
User time for the children processes
*)tms_cstime : float;
System time for the children processes
*)}
The execution times (CPU times) of a process.
type tm = Unix.tm = {
tm_sec : int;
Seconds 0..60
*)tm_min : int;
Minutes 0..59
*)tm_hour : int;
Hours 0..23
*)tm_mday : int;
Day of month 1..31
*)tm_mon : int;
Month of year 0..11
*)tm_year : int;
Year - 1900
*)tm_wday : int;
Day of week (Sunday is 0)
*)tm_yday : int;
Day of year 0..365
*)tm_isdst : bool;
Daylight time savings in effect
*)}
The type representing wallclock time and calendar date.
Same as time
, but with resolution better than 1 second.
val gmtime : float -> tm
val localtime : float -> tm
Convert a date and time, specified by the tm
argument, into a time in seconds, as returned by time
. The tm_isdst
, tm_wday
and tm_yday
fields of tm
are ignored. Also return a normalized copy of the given tm
record, with the tm_wday
, tm_yday
, and tm_isdst
fields recomputed from the other fields, and the other fields normalized (so that, e.g., 40 October is changed into 9 November). The tm
argument is interpreted in the local time zone.
Stop execution for the given number of seconds. Like sleep
, but fractions of seconds are supported.
val times : unit -> process_times
Return the execution times of the process.
On Windows: partially implemented, will not report timings for child processes.
Set the last access time (second arg) and last modification time (third arg) for a file. Times are expressed in seconds from 00:00:00 GMT, Jan. 1, 1970. If both times are 0.0
, the access and last modification times are both set to the current time.
type interval_timer = Unix.interval_timer =
| ITIMER_REAL
decrements in real time, and sends the signal SIGALRM
when expired.
| ITIMER_VIRTUAL
decrements in process virtual time, and sends SIGVTALRM
when expired.
| ITIMER_PROF
(for profiling) decrements both when the process is running and when the system is running on behalf of the process; it sends SIGPROF
when expired.
The three kinds of interval timers.
The type describing the status of an interval timer
val getitimer : interval_timer -> interval_timer_status
Return the current status of the given interval timer.
val setitimer :
interval_timer ->
interval_timer_status ->
interval_timer_status
setitimer t s
sets the interval timer t
and returns its previous status. The s
argument is interpreted as follows: s.it_value
, if nonzero, is the time to the next timer expiration; s.it_interval
, if nonzero, specifies a value to be used in reloading it_value
when the timer expires. Setting s.it_value
to zero disables the timer. Setting s.it_interval
to zero causes the timer to be disabled after its next expiration.
Return the user id of the user executing the process.
On Windows: always returns 1
.
Return the effective user id under which the process runs.
On Windows: always returns 1
.
Return the group id of the user executing the process.
On Windows: always returns 1
.
Return the effective group id under which the process runs.
On Windows: always returns 1
.
Return the list of groups to which the user executing the process belongs.
On Windows: always returns [|1|]
.
setgroups groups
sets the supplementary group IDs for the calling process. Appropriate privileges are required.
initgroups user group
initializes the group access list by reading the group database /etc/group and using all groups of which user
is a member. The additional group group
is also added to the list.
type passwd_entry = Unix.passwd_entry = {
pw_name : string;
pw_passwd : string;
pw_uid : int;
pw_gid : int;
pw_gecos : string;
pw_dir : string;
pw_shell : string;
}
Structure of entries in the passwd
database.
Structure of entries in the groups
database.
val getpwnam : string -> passwd_entry
Find an entry in passwd
with the given name.
val getgrnam : string -> group_entry
Find an entry in group
with the given name.
val getpwuid : int -> passwd_entry
Find an entry in passwd
with the given user id.
val getgrgid : int -> group_entry
Find an entry in group
with the given group id.
type inet_addr = Unix.inet_addr
The abstract type of Internet addresses.
val inet_addr_of_string : string -> inet_addr
Conversion from the printable representation of an Internet address to its internal representation. The argument string consists of 4 numbers separated by periods (XXX.YYY.ZZZ.TTT
) for IPv4 addresses, and up to 8 numbers separated by colons for IPv6 addresses.
val string_of_inet_addr : inet_addr -> string
Return the printable representation of the given Internet address. See inet_addr_of_string
for a description of the printable representation.
val inet_addr_any : inet_addr
A special IPv4 address, for use only with bind
, representing all the Internet addresses that the host machine possesses.
val inet_addr_loopback : inet_addr
A special IPv4 address representing the host machine (127.0.0.1
).
val inet6_addr_any : inet_addr
A special IPv6 address, for use only with bind
, representing all the Internet addresses that the host machine possesses.
val inet6_addr_loopback : inet_addr
A special IPv6 address representing the host machine (::1
).
val is_inet6_addr : inet_addr -> bool
Whether the given inet_addr
is an IPv6 address.
type socket_domain = Unix.socket_domain =
The type of socket domains. Not all platforms support IPv6 sockets (type PF_INET6
).
On Windows: PF_UNIX
supported since 4.14.0 on Windows 10 1803 and later.
type socket_type = Unix.socket_type =
The type of socket kinds, specifying the semantics of communications. SOCK_SEQPACKET
is included for completeness, but is rarely supported by the OS, and needs system calls that are not available in this library.
The type of socket addresses. ADDR_UNIX name
is a socket address in the Unix domain; name
is a file name in the file system. ADDR_INET(addr,port)
is a socket address in the Internet domain; addr
is the Internet address of the machine, and port
is the port number.
val socket :
?cloexec:bool ->
domain:socket_domain ->
kind:socket_type ->
protocol:int ->
file_descr
Create a new socket in the given domain, and with the given kind. The third argument is the protocol type; 0 selects the default protocol for that kind of sockets. See set_close_on_exec
for documentation on the cloexec
optional argument.
val domain_of_sockaddr : sockaddr -> socket_domain
Return the socket domain adequate for the given socket address.
val socketpair :
?cloexec:bool ->
domain:socket_domain ->
kind:socket_type ->
protocol:int ->
file_descr * file_descr
Create a pair of unnamed sockets, connected together. See set_close_on_exec
for documentation on the cloexec
optional argument.
val accept : ?cloexec:bool -> file_descr -> file_descr * sockaddr
Accept connections on the given socket. The returned descriptor is a socket connected to the client; the returned address is the address of the connecting client. See set_close_on_exec
for documentation on the cloexec
optional argument.
val bind : file_descr -> addr:sockaddr -> unit
Bind a socket to an address.
val connect : file_descr -> addr:sockaddr -> unit
Connect a socket to an address.
val listen : file_descr -> max:int -> unit
Set up a socket for receiving connection requests. The integer argument is the maximal number of pending requests.
type shutdown_command = Unix.shutdown_command =
The type of commands for shutdown
.
val shutdown : file_descr -> mode:shutdown_command -> unit
Shutdown a socket connection. SHUTDOWN_SEND
as second argument causes reads on the other end of the connection to return an end-of-file condition. SHUTDOWN_RECEIVE
causes writes on the other end of the connection to return a closed pipe condition (SIGPIPE
signal).
val getsockname : file_descr -> sockaddr
Return the address of the given socket.
val getpeername : file_descr -> sockaddr
Return the address of the host connected to the given socket.
val recv :
file_descr ->
buf:bytes ->
pos:int ->
len:int ->
mode:msg_flag list ->
int
Receive data from a connected socket.
val recvfrom :
file_descr ->
buf:bytes ->
pos:int ->
len:int ->
mode:msg_flag list ->
int * sockaddr
Receive data from an unconnected socket.
val send :
file_descr ->
buf:bytes ->
pos:int ->
len:int ->
mode:msg_flag list ->
int
Send data over a connected socket.
val send_substring :
file_descr ->
buf:string ->
pos:int ->
len:int ->
mode:msg_flag list ->
int
Same as send
, but take the data from a string instead of a byte sequence.
val sendto :
file_descr ->
buf:bytes ->
pos:int ->
len:int ->
mode:msg_flag list ->
addr:sockaddr ->
int
Send data over an unconnected socket.
val sendto_substring :
file_descr ->
buf:string ->
pos:int ->
len:int ->
mode:msg_flag list ->
sockaddr ->
int
Same as sendto
, but take the data from a string instead of a byte sequence.
type socket_bool_option = Unix.socket_bool_option =
| SO_DEBUG
Record debugging information
*)| SO_BROADCAST
Permit sending of broadcast messages
*)| SO_REUSEADDR
Allow reuse of local addresses for bind
*)| SO_KEEPALIVE
Keep connection active
*)| SO_DONTROUTE
Bypass the standard routing algorithms
*)| SO_OOBINLINE
Leave out-of-band data in line
*)| SO_ACCEPTCONN
Report whether socket listening is enabled
*)| TCP_NODELAY
Control the Nagle algorithm for TCP sockets
*)| IPV6_ONLY
Forbid binding an IPv6 socket to an IPv4 address
*)| SO_REUSEPORT
Allow reuse of address and port bindings
*)The socket options that can be consulted with getsockopt
and modified with setsockopt
. These options have a boolean (true
/false
) value.
type socket_int_option = Unix.socket_int_option =
The socket options that can be consulted with getsockopt_int
and modified with setsockopt_int
. These options have an integer value.
type socket_optint_option = Unix.socket_optint_option =
The socket options that can be consulted with getsockopt_optint
and modified with setsockopt_optint
. These options have a value of type int option
, with None
meaning ``disabled''.
type socket_float_option = Unix.socket_float_option =
The socket options that can be consulted with getsockopt_float
and modified with setsockopt_float
. These options have a floating-point value representing a time in seconds. The value 0 means infinite timeout.
val getsockopt : file_descr -> socket_bool_option -> bool
Return the current status of a boolean-valued option in the given socket.
val setsockopt : file_descr -> socket_bool_option -> bool -> unit
Set or clear a boolean-valued option in the given socket.
val getsockopt_int : file_descr -> socket_int_option -> int
Same as getsockopt
for an integer-valued socket option.
val setsockopt_int : file_descr -> socket_int_option -> int -> unit
Same as setsockopt
for an integer-valued socket option.
val getsockopt_optint : file_descr -> socket_optint_option -> int option
Same as getsockopt
for a socket option whose value is an int option
.
val setsockopt_optint :
file_descr ->
socket_optint_option ->
int option ->
unit
Same as setsockopt
for a socket option whose value is an int option
.
val getsockopt_float : file_descr -> socket_float_option -> float
Same as getsockopt
for a socket option whose value is a floating-point number.
val setsockopt_float : file_descr -> socket_float_option -> float -> unit
Same as setsockopt
for a socket option whose value is a floating-point number.
val getsockopt_error : file_descr -> error option
Return the error condition associated with the given socket, and clear it.
val open_connection : sockaddr -> in_channel * out_channel
Connect to a server at the given address. Return a pair of buffered channels connected to the server. Remember to call Stdlib.flush
on the output channel at the right times to ensure correct synchronization.
The two channels returned by open_connection
share a descriptor to a socket. Therefore, when the connection is over, you should call Stdlib.close_out
on the output channel, which will also close the underlying socket. Do not call Stdlib.close_in
on the input channel; it will be collected by the GC eventually.
val shutdown_connection : in_channel -> unit
``Shut down'' a connection established with open_connection
; that is, transmit an end-of-file condition to the server reading on the other side of the connection. This does not close the socket and the channels used by the connection. See Unix.open_connection
for how to close them once the connection is over.
val establish_server :
(in_channel -> out_channel -> unit) ->
addr:sockaddr ->
unit
Establish a server on the given address. The function given as first argument is called for each connection with two buffered channels connected to the client. A new process is created for each connection. The function establish_server
never returns normally.
The two channels given to the function share a descriptor to a socket. The function does not need to close the channels, since this occurs automatically when the function returns. If the function prefers explicit closing, it should close the output channel using Stdlib.close_out
and leave the input channel unclosed, for reasons explained in Unix.in_channel_of_descr
.
type host_entry = Unix.host_entry = {
h_name : string;
h_aliases : string array;
h_addrtype : socket_domain;
h_addr_list : inet_addr array;
}
Structure of entries in the hosts
database.
Structure of entries in the protocols
database.
Structure of entries in the services
database.
val gethostbyname : string -> host_entry
Find an entry in hosts
with the given name.
val gethostbyaddr : inet_addr -> host_entry
Find an entry in hosts
with the given address.
val getprotobyname : string -> protocol_entry
Find an entry in protocols
with the given name.
val getprotobynumber : int -> protocol_entry
Find an entry in protocols
with the given protocol number.
val getservbyname : string -> protocol:string -> service_entry
Find an entry in services
with the given name.
val getservbyport : int -> protocol:string -> service_entry
Find an entry in services
with the given service number.
type addr_info = Unix.addr_info = {
ai_family : socket_domain;
Socket domain
*)ai_socktype : socket_type;
Socket type
*)ai_protocol : int;
Socket protocol number
*)ai_addr : sockaddr;
Address
*)ai_canonname : string;
Canonical host name
*)}
Address information returned by getaddrinfo
.
type getaddrinfo_option = Unix.getaddrinfo_option =
| AI_FAMILY of socket_domain
Impose the given socket domain
*)| AI_SOCKTYPE of socket_type
Impose the given socket type
*)| AI_PROTOCOL of int
Impose the given protocol
*)| AI_NUMERICHOST
Do not call name resolver, expect numeric IP address
*)| AI_CANONNAME
Fill the ai_canonname
field of the result
| AI_PASSIVE
Options to getaddrinfo
.
val getaddrinfo : string -> string -> getaddrinfo_option list -> addr_info list
getaddrinfo host service opts
returns a list of addr_info
records describing socket parameters and addresses suitable for communicating with the given host and service. The empty list is returned if the host or service names are unknown, or the constraints expressed in opts
cannot be satisfied.
host
is either a host name or the string representation of an IP address. host
can be given as the empty string; in this case, the ``any'' address or the ``loopback'' address are used, depending whether opts
contains AI_PASSIVE
. service
is either a service name or the string representation of a port number. service
can be given as the empty string; in this case, the port field of the returned addresses is set to 0. opts
is a possibly empty list of options that allows the caller to force a particular socket domain (e.g. IPv6 only or IPv4 only) or a particular socket type (e.g. TCP only or UDP only).
type name_info = Unix.name_info = {
ni_hostname : string;
Name or IP address of host
*)ni_service : string;
Name of service or port number
*)}
Host and service information returned by getnameinfo
.
type getnameinfo_option = Unix.getnameinfo_option =
Options to getnameinfo
.
val getnameinfo : sockaddr -> getnameinfo_option list -> name_info
getnameinfo addr opts
returns the host name and service name corresponding to the socket address addr
. opts
is a possibly empty list of options that governs how these names are obtained.
The following functions implement the POSIX standard terminal interface. They provide control over asynchronous communication ports and pseudo-terminals. Refer to the termios
man page for a complete description.
type terminal_io = Unix.terminal_io = {
mutable c_ignbrk : bool;
Ignore the break condition.
*)mutable c_brkint : bool;
Signal interrupt on break condition.
*)mutable c_ignpar : bool;
Ignore characters with parity errors.
*)mutable c_parmrk : bool;
Mark parity errors.
*)mutable c_inpck : bool;
Enable parity check on input.
*)mutable c_istrip : bool;
Strip 8th bit on input characters.
*)mutable c_inlcr : bool;
Map NL to CR on input.
*)mutable c_igncr : bool;
Ignore CR on input.
*)mutable c_icrnl : bool;
Map CR to NL on input.
*)mutable c_ixon : bool;
Recognize XON/XOFF characters on input.
*)mutable c_ixoff : bool;
Emit XON/XOFF chars to control input flow.
*)mutable c_opost : bool;
Enable output processing.
*)mutable c_obaud : int;
Output baud rate (0 means close connection).
*)mutable c_ibaud : int;
Input baud rate.
*)mutable c_csize : int;
Number of bits per character (5-8).
*)mutable c_cstopb : int;
Number of stop bits (1-2).
*)mutable c_cread : bool;
Reception is enabled.
*)mutable c_parenb : bool;
Enable parity generation and detection.
*)mutable c_parodd : bool;
Specify odd parity instead of even.
*)mutable c_hupcl : bool;
Hang up on last close.
*)mutable c_clocal : bool;
Ignore modem status lines.
*)mutable c_isig : bool;
Generate signal on INTR, QUIT, SUSP.
*)mutable c_icanon : bool;
Enable canonical processing (line buffering and editing)
*)mutable c_noflsh : bool;
Disable flush after INTR, QUIT, SUSP.
*)mutable c_echo : bool;
Echo input characters.
*)mutable c_echoe : bool;
Echo ERASE (to erase previous character).
*)mutable c_echok : bool;
Echo KILL (to erase the current line).
*)mutable c_echonl : bool;
Echo NL even if c_echo is not set.
*)mutable c_vintr : char;
Interrupt character (usually ctrl-C).
*)mutable c_vquit : char;
Quit character (usually ctrl-\).
*)mutable c_verase : char;
Erase character (usually DEL or ctrl-H).
*)mutable c_vkill : char;
Kill line character (usually ctrl-U).
*)mutable c_veof : char;
End-of-file character (usually ctrl-D).
*)mutable c_veol : char;
Alternate end-of-line char. (usually none).
*)mutable c_vmin : int;
Minimum number of characters to read before the read request is satisfied.
*)mutable c_vtime : int;
Maximum read wait (in 0.1s units).
*)mutable c_vstart : char;
Start character (usually ctrl-Q).
*)mutable c_vstop : char;
Stop character (usually ctrl-S).
*)}
val tcgetattr : file_descr -> terminal_io
Return the status of the terminal referred to by the given file descriptor.
val tcsetattr : file_descr -> mode:setattr_when -> terminal_io -> unit
Set the status of the terminal referred to by the given file descriptor. The second argument indicates when the status change takes place: immediately (TCSANOW
), when all pending output has been transmitted (TCSADRAIN
), or after flushing all input that has been received but not read (TCSAFLUSH
). TCSADRAIN
is recommended when changing the output parameters; TCSAFLUSH
, when changing the input parameters.
val tcsendbreak : file_descr -> duration:int -> unit
Send a break condition on the given file descriptor. The second argument is the duration of the break, in 0.1s units; 0 means standard duration (0.25s).
val tcdrain : file_descr -> unit
Waits until all output written on the given file descriptor has been transmitted.
val tcflush : file_descr -> mode:flush_queue -> unit
Discard data written on the given file descriptor but not yet transmitted, or data received but not yet read, depending on the second argument: TCIFLUSH
flushes data received but not read, TCOFLUSH
flushes data written but not transmitted, and TCIOFLUSH
flushes both.
val tcflow : file_descr -> mode:flow_action -> unit
Suspend or restart reception or transmission of data on the given file descriptor, depending on the second argument: TCOOFF
suspends output, TCOON
restarts output, TCIOFF
transmits a STOP character to suspend input, and TCION
transmits a START character to restart input.