.TH "Unix" 3 2024-05-31 OCamldoc "OCaml library" .SH NAME Unix \- Interface to the Unix system. .SH Module Module Unix .SH Documentation .sp Module .BI "Unix" : .B sig end .sp Interface to the Unix system\&. .sp To use the labeled version of this module, add .ft B module Unix .ft R .ft B = .ft R .ft B UnixLabels .ft R in your implementation\&. .sp Note: all the functions of this module (except .ft B Unix\&.error_message .ft R and .ft B Unix\&.handle_unix_error .ft R ) are liable to raise the .ft B Unix\&.Unix_error .ft R exception whenever the underlying system call signals an error\&. .sp .sp .sp .PP .SS Error report .PP .I type 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 .B of .B int .I " " (* Unknown error *) .sp 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\&. .sp .I exception Unix_error .B of .B error * string * string .sp 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\&. .sp .ft B UnixLabels\&.Unix_error .ft R and .ft B Unix\&.Unix_error .ft R are the same, and catching one will catch the other\&. .sp .I val error_message : .B error -> string .sp Return a string describing the given error code\&. .sp .I val handle_unix_error : .B ('a -> 'b) -> 'a -> 'b .sp .ft B handle_unix_error f x .ft R applies .ft B f .ft R to .ft B x .ft R and returns the result\&. If the exception .ft B Unix\&.Unix_error .ft R is raised, it prints a message describing the error and exits with code 2\&. .sp .PP .SS Access to the process environment .PP .I val environment : .B unit -> string array .sp 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\&. .sp .I val unsafe_environment : .B unit -> string array .sp Return the process environment, as an array of strings with the format ``variable=value\&'\&'\&. Unlike .ft B Unix\&.environment .ft R , this function returns a populated array even if the process has special privileges\&. See the documentation for .ft B Unix\&.unsafe_getenv .ft R for more details\&. .sp .B "Since" 4.06 (4.12 in UnixLabels) .sp .I val getenv : .B string -> string .sp Return the value associated to a variable in the process environment, unless the process has special privileges\&. .sp .B "Raises Not_found" if the variable is unbound or the process has special privileges\&. .sp This function is identical to .ft B Sys\&.getenv .ft R \&. .sp .I val unsafe_getenv : .B string -> string .sp Return the value associated to a variable in the process environment\&. .sp Unlike .ft B Unix\&.getenv .ft R , 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\&. .sp .B "Since" 4.06 .sp .B "Raises Not_found" if the variable is unbound\&. .sp .I val putenv : .B string -> string -> unit .sp .ft B putenv name value .ft R sets the value associated to a variable in the process environment\&. .ft B name .ft R is the name of the environment variable, and .ft B value .ft R its new associated value\&. .sp .PP .SS Process handling .PP .I type process_status = | WEXITED .B of .B int .I " " (* The process terminated normally by .ft B exit .ft R ; the argument is the return code\&. *) | WSIGNALED .B of .B int .I " " (* The process was killed by a signal; the argument is the signal number\&. *) | WSTOPPED .B of .B int .I " " (* The process was stopped by a signal; the argument is the signal number\&. *) .sp The termination status of a process\&. See module .ft B Sys .ft R for the definitions of the standard signal numbers\&. Note that they are not the numbers used by the OS\&. .sp On Windows: only .ft B WEXITED .ft R is used (as there are no inter\-process signals) but with specific return codes to indicate special termination causes\&. Look for .ft B NTSTATUS .ft R values in the Windows documentation to decode such error return codes\&. In particular, .ft B STATUS_ACCESS_VIOLATION .ft R error code is the 32\-bit .ft B 0xC0000005 .ft R : as .ft B Int32\&.of_int 0xC0000005 .ft R is .ft B \-1073741819 .ft R , .ft B WEXITED \-1073741819 .ft R is the Windows equivalent of .ft B WSIGNALED Sys\&.sigsegv .ft R \&. .sp .I type wait_flag = | WNOHANG (* Do not block if no child has died yet, but immediately return with a pid equal to 0\&. *) | WUNTRACED (* Report also the children that receive stop signals\&. *) .sp Flags for .ft B Unix\&.waitpid .ft R \&. .sp .I val execv : .B string -> string array -> 'a .sp .ft B execv prog args .ft R execute the program in file .ft B prog .ft R , with the arguments .ft B args .ft R , and the current process environment\&. Note that the first argument, .ft B args\&.(0) .ft R , is by convention the filename of the program being executed, just like .ft B Sys\&.argv\&.(0) .ft R \&. These .ft B execv* .ft R functions never return: on success, the current program is replaced by the new one\&. .sp 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 .ft B Unix\&.create_process .ft R or one of the .ft B open_process_* .ft R functions instead is recommended\&. .sp .B "Raises Unix_error" on failure .sp .I val execve : .B string -> string array -> string array -> 'a .sp Same as .ft B Unix\&.execv .ft R , except that the third argument provides the environment to the program executed\&. .sp .I val execvp : .B string -> string array -> 'a .sp Same as .ft B Unix\&.execv .ft R , except that the program is searched in the path\&. .sp .I val execvpe : .B string -> string array -> string array -> 'a .sp Same as .ft B Unix\&.execve .ft R , except that the program is searched in the path\&. .sp .I val fork : .B unit -> int .sp Fork a new process\&. The returned integer is 0 for the child process, the pid of the child process for the parent process\&. It fails if the OCaml process is multi\-core (any domain has been spawned)\&. In addition, if any thread from the Thread module has been spawned, then the child process might be in a corrupted state\&. .sp .B "Raises Invalid_argument" on Windows\&. Use .ft B Unix\&.create_process .ft R or threads instead\&. .sp .B "Raises Failure" if any domain has been spawned\&. .sp .I val wait : .B unit -> int * process_status .sp Wait until one of the children processes die, and return its pid and termination status\&. .sp .B "Raises Invalid_argument" on Windows\&. Use .ft B Unix\&.waitpid .ft R instead\&. .sp .I val waitpid : .B wait_flag list -> int -> int * process_status .sp Same as .ft B Unix\&.wait .ft R , but waits for the child process whose pid is given\&. A pid of .ft B \-1 .ft R means wait for any child\&. A pid of .ft B 0 .ft R 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 .ft B waitpid .ft R should return immediately without waiting, and whether it should report stopped children\&. .sp On Windows: can only wait for a given PID, not any child process\&. .sp .I val system : .B string -> process_status .sp Execute the given command, wait until it terminates, and return its termination status\&. The string is interpreted by the shell .ft B /bin/sh .ft R (or the command interpreter .ft B cmd\&.exe .ft R 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 .ft B Filename\&.quote_command .ft R is recommended\&. The result .ft B WEXITED 127 .ft R indicates that the shell couldn\&'t be executed\&. .sp .I val _exit : .B int -> 'a .sp 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 .ft B exit .ft R , .ft B Unix\&._exit .ft R performs no finalization whatsoever: functions registered with .ft B at_exit .ft R are not called, input/output channels are not flushed, and the C run\-time system is not finalized either\&. .sp The typical use of .ft B Unix\&._exit .ft R is after a .ft B Unix\&.fork .ft R 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\&. .sp .B "Since" 4.12 .sp .I val getpid : .B unit -> int .sp Return the pid of the process\&. .sp .I val getppid : .B unit -> int .sp Return the pid of the parent process\&. .sp .B "Raises Invalid_argument" on Windows (because it is meaningless) .sp .I val nice : .B int -> int .sp 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\&. .sp .B "Raises Invalid_argument" on Windows .sp .PP .SS Basic file input/output .PP .I type file_descr .sp The abstract type of file descriptors\&. .sp .I val stdin : .B file_descr .sp File descriptor for standard input\&. .sp .I val stdout : .B file_descr .sp File descriptor for standard output\&. .sp .I val stderr : .B file_descr .sp File descriptor for standard error\&. .sp .I type 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 .ft B Unix\&.openfile .ft R \&. See .ft B Unix\&.set_close_on_exec .ft R for more information\&. *) | O_KEEPEXEC (* Clear the close\-on\-exec flag\&. This is currently the default\&. *) .sp The flags to .ft B Unix\&.openfile .ft R \&. .sp .I type file_perm = .B int .sp The type of file access rights, e\&.g\&. .ft B 0o640 .ft R is read and write for user, read for group, none for others .sp .I val openfile : .B string -> open_flag list -> file_perm -> file_descr .sp Open the named file with the given flags\&. Third argument is the permissions to give to the file if it is created (see .ft B Unix\&.umask .ft R )\&. Return a file descriptor on the named file\&. .sp .I val close : .B file_descr -> unit .sp Close a file descriptor\&. .sp .I val fsync : .B file_descr -> unit .sp Flush file buffers to disk\&. .sp .B "Since" 4.08 (4.12 in UnixLabels) .sp .I val read : .B file_descr -> bytes -> int -> int -> int .sp .ft B read fd buf pos len .ft R reads .ft B len .ft R bytes from descriptor .ft B fd .ft R , storing them in byte sequence .ft B buf .ft R , starting at position .ft B pos .ft R in .ft B buf .ft R \&. Return the number of bytes actually read\&. .sp .I val read_bigarray : .B file_descr -> .B ('a, Bigarray.int8_unsigned_elt, Bigarray.c_layout) .B Bigarray.Array1.t -> int -> int -> int .sp Same as .ft B Unix\&.read .ft R , but read the data into a bigarray\&. .sp .B "Since" 5.2 .sp .I val write : .B file_descr -> bytes -> int -> int -> int .sp .ft B write fd buf pos len .ft R writes .ft B len .ft R bytes to descriptor .ft B fd .ft R , taking them from byte sequence .ft B buf .ft R , starting at position .ft B pos .ft R in .ft B buff .ft R \&. Return the number of bytes actually written\&. .ft B write .ft R repeats the writing operation until all bytes have been written or an error occurs\&. .sp .I val write_bigarray : .B file_descr -> .B ('a, Bigarray.int8_unsigned_elt, Bigarray.c_layout) .B Bigarray.Array1.t -> int -> int -> int .sp Same as .ft B Unix\&.write .ft R , but take the data from a bigarray\&. .sp .B "Since" 5.2 .sp .I val single_write : .B file_descr -> bytes -> int -> int -> int .sp Same as .ft B Unix\&.write .ft R , but attempts to write only once\&. Thus, if an error occurs, .ft B single_write .ft R guarantees that no data has been written\&. .sp .I val write_substring : .B file_descr -> string -> int -> int -> int .sp Same as .ft B Unix\&.write .ft R , but take the data from a string instead of a byte sequence\&. .sp .B "Since" 4.02 .sp .I val single_write_substring : .B file_descr -> string -> int -> int -> int .sp Same as .ft B Unix\&.single_write .ft R , but take the data from a string instead of a byte sequence\&. .sp .B "Since" 4.02 .sp .I val single_write_bigarray : .B file_descr -> .B ('a, Bigarray.int8_unsigned_elt, Bigarray.c_layout) .B Bigarray.Array1.t -> int -> int -> int .sp Same as .ft B Unix\&.single_write .ft R , but take the data from a bigarray\&. .sp .B "Since" 5.2 .sp .PP .SS Interfacing with the standard input/output library .PP .I val in_channel_of_descr : .B file_descr -> in_channel .sp Create an input channel reading from the given descriptor\&. The channel is initially in binary mode; use .ft B set_binary_mode_in ic false .ft R 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\&. .sp On Windows: .ft B set_binary_mode_in .ft R always fails on channels created with this function\&. .sp 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\&. .sp Closing the channel .ft B ic .ft R returned by .ft B in_channel_of_descr fd .ft R using .ft B close_in ic .ft R also closes the underlying descriptor .ft B fd .ft R \&. It is incorrect to close both the channel .ft B ic .ft R and the descriptor .ft B fd .ft R \&. .sp 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 .ft B s .ft R connected to a socket and two channels .ft B ic = in_channel_of_descr s .ft R and .ft B oc = out_channel_of_descr s .ft R \&. The recommended closing protocol is to perform .ft B close_out oc .ft R , which flushes buffered output to the socket then closes the socket\&. The .ft B ic .ft R channel must not be closed and will be collected by the GC eventually\&. .sp .I val out_channel_of_descr : .B file_descr -> out_channel .sp Create an output channel writing on the given descriptor\&. The channel is initially in binary mode; use .ft B set_binary_mode_out oc false .ft R 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\&. .sp On Windows: .ft B set_binary_mode_out .ft R always fails on channels created with this function\&. .sp Beware that output channels are buffered, so you may have to call .ft B flush .ft R to ensure that all data has been sent to the descriptor\&. Channels also keep a copy of the current position in the file\&. .sp Closing the channel .ft B oc .ft R returned by .ft B out_channel_of_descr fd .ft R using .ft B close_out oc .ft R also closes the underlying descriptor .ft B fd .ft R \&. It is incorrect to close both the channel .ft B ic .ft R and the descriptor .ft B fd .ft R \&. .sp See .ft B Unix\&.in_channel_of_descr .ft R for a discussion of the closing protocol when several channels are created on the same descriptor\&. .sp .I val descr_of_in_channel : .B in_channel -> file_descr .sp Return the descriptor corresponding to an input channel\&. .sp .I val descr_of_out_channel : .B out_channel -> file_descr .sp Return the descriptor corresponding to an output channel\&. .sp .PP .SS Seeking and truncating .PP .I type seek_command = | SEEK_SET (* indicates positions relative to the beginning of the file *) | SEEK_CUR (* indicates positions relative to the current position *) | SEEK_END (* indicates positions relative to the end of the file *) .sp Positioning modes for .ft B Unix\&.lseek .ft R \&. .sp .I val lseek : .B file_descr -> int -> seek_command -> int .sp Set the current position for a file descriptor, and return the resulting offset (from the beginning of the file)\&. .sp .I val truncate : .B string -> int -> unit .sp Truncates the named file to the given size\&. .sp .I val ftruncate : .B file_descr -> int -> unit .sp Truncates the file corresponding to the given descriptor to the given size\&. .sp .PP .SS File status .PP .I type file_kind = | S_REG (* Regular file *) | S_DIR (* Directory *) | S_CHR (* Character device *) | S_BLK (* Block device *) | S_LNK (* Symbolic link *) | S_FIFO (* Named pipe *) | S_SOCK (* Socket *) .sp .sp .I type stats = { st_dev : .B int ; (* Device number *) st_ino : .B int ; (* Inode number *) st_kind : .B file_kind ; (* Kind of the file *) st_perm : .B file_perm ; (* Access rights *) st_nlink : .B int ; (* Number of links *) st_uid : .B int ; (* User id of the owner *) st_gid : .B int ; (* Group ID of the file\&'s group *) st_rdev : .B int ; (* Device ID (if special file) *) st_size : .B int ; (* Size in bytes *) st_atime : .B float ; (* Last access time *) st_mtime : .B float ; (* Last modification time *) st_ctime : .B float ; (* Last status change time *) } .sp The information returned by the .ft B Unix\&.stat .ft R calls\&. .sp .I val stat : .B string -> stats .sp Return the information for the named file\&. .sp .I val lstat : .B string -> stats .sp Same as .ft B Unix\&.stat .ft R , but in case the file is a symbolic link, return the information for the link itself\&. .sp .I val fstat : .B file_descr -> stats .sp Return the information for the file associated with the given descriptor\&. .sp .I val isatty : .B file_descr -> bool .sp Return .ft B true .ft R if the given file descriptor refers to a terminal or console window, .ft B false .ft R otherwise\&. .sp .PP .SS File operations on large files .PP .I module LargeFile : .B sig end .sp File operations on large files\&. This sub\-module provides 64\-bit variants of the functions .ft B Unix\&.LargeFile\&.lseek .ft R (for positioning a file descriptor), .ft B Unix\&.LargeFile\&.truncate .ft R and .ft B Unix\&.LargeFile\&.ftruncate .ft R (for changing the size of a file), and .ft B Unix\&.LargeFile\&.stat .ft R , .ft B Unix\&.LargeFile\&.lstat .ft R and .ft B Unix\&.LargeFile\&.fstat .ft R (for obtaining information on files)\&. These alternate functions represent positions and sizes by 64\-bit integers (type .ft B int64 .ft R ) instead of regular integers (type .ft B int .ft R ), thus allowing operating on files whose sizes are greater than .ft B max_int .ft R \&. .sp .PP .SS Mapping files into memory .PP .I val map_file : .B file_descr -> .B ?pos:int64 -> .B ('a, 'b) Bigarray.kind -> .B 'c Bigarray.layout -> .B bool -> int array -> ('a, 'b, 'c) Bigarray.Genarray.t .sp Memory mapping of a file as a Bigarray\&. .ft B map_file fd kind layout shared dims .ft R returns a Bigarray of kind .ft B kind .ft R , layout .ft B layout .ft R , and dimensions as specified in .ft B dims .ft R \&. The data contained in this Bigarray are the contents of the file referred to by the file descriptor .ft B fd .ft R (as opened previously with .ft B Unix\&.openfile .ft R , for example)\&. The optional .ft B pos .ft R parameter is the byte offset in the file of the data being mapped; it defaults to 0 (map from the beginning of the file)\&. .sp If .ft B shared .ft R is .ft B true .ft R , all modifications performed on the array are reflected in the file\&. This requires that .ft B fd .ft R be opened with write permissions\&. If .ft B shared .ft R is .ft B false .ft R , modifications performed on the array are done in memory only, using copy\-on\-write of the modified pages; the underlying file is not affected\&. .sp .ft B Unix\&.map_file .ft R is much more efficient than reading the whole file in a Bigarray, modifying that Bigarray, and writing it afterwards\&. .sp 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 .ft B \-1 .ft R \&. .ft B Unix\&.map_file .ft R 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 .ft B Failure .ft R is raised\&. .sp 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 .ft B fd .ft R \&. .sp Array accesses are bounds\-checked, but the bounds are determined by the initial call to .ft B map_file .ft R \&. 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\&. .sp .ft B Invalid_argument .ft R or .ft B Failure .ft R may be raised in cases where argument validation fails\&. .sp .B "Since" 4.06 .sp .PP .SS Operations on file names .PP .I val unlink : .B string -> unit .sp Removes the named file\&. .sp If the named file is a directory, raises: .sp \- .ft B EPERM .ft R on POSIX compliant system .sp \- .ft B EISDIR .ft R on Linux >= 2\&.1\&.132 .sp \- .ft B EACCESS .ft R on Windows .sp .I val rename : .B string -> string -> unit .sp .ft B rename src dst .ft R changes the name of a file from .ft B src .ft R to .ft B dst .ft R , moving it between directories if needed\&. If .ft B dst .ft R already exists, its contents will be replaced with those of .ft B src .ft R \&. Depending on the operating system, the metadata (permissions, owner, etc) of .ft B dst .ft R can either be preserved or be replaced by those of .ft B src .ft R \&. .sp .I val link : .B ?follow:bool -> string -> string -> unit .sp .ft B link ?follow src dst .ft R creates a hard link named .ft B dst .ft R to the file named .ft B src .ft R \&. .sp .B "Raises ENOSYS" On Unix if .ft B ~follow:_ .ft R is requested, but linkat is unavailable\&. .sp .B "Raises ENOSYS" On Windows if .ft B ~follow:false .ft R is requested\&. .sp .I val realpath : .B string -> string .sp .ft B realpath p .ft R is an absolute pathname for .ft B p .ft R obtained by resolving all extra .ft B / .ft R characters, relative path segments and symbolic links\&. .sp .B "Since" 4.13 .sp .PP .SS File permissions and ownership .PP .I type access_permission = | R_OK (* Read permission *) | W_OK (* Write permission *) | X_OK (* Execution permission *) | F_OK (* File exists *) .sp Flags for the .ft B Unix\&.access .ft R call\&. .sp .I val chmod : .B string -> file_perm -> unit .sp Change the permissions of the named file\&. .sp .I val fchmod : .B file_descr -> file_perm -> unit .sp Change the permissions of an opened file\&. .sp .B "Raises Invalid_argument" on Windows .sp .I val chown : .B string -> int -> int -> unit .sp Change the owner uid and owner gid of the named file\&. .sp .B "Raises Invalid_argument" on Windows .sp .I val fchown : .B file_descr -> int -> int -> unit .sp Change the owner uid and owner gid of an opened file\&. .sp .B "Raises Invalid_argument" on Windows .sp .I val umask : .B file_perm -> file_perm .sp Set the process\&'s file mode creation mask, and return the previous mask\&. .sp .B "Raises Invalid_argument" on Windows .sp .I val access : .B string -> access_permission list -> unit .sp Check that the process has the given permissions over the named file\&. .sp On Windows: execute permission .ft B X_OK .ft R cannot be tested, just tests for read permission instead\&. .sp .B "Raises Unix_error" otherwise\&. .sp .PP .SS Operations on file descriptors .PP .I val dup : .B ?cloexec:bool -> file_descr -> file_descr .sp Return a new file descriptor referencing the same file as the given descriptor\&. See .ft B Unix\&.set_close_on_exec .ft R for documentation on the .ft B cloexec .ft R optional argument\&. .sp .I val dup2 : .B ?cloexec:bool -> file_descr -> file_descr -> unit .sp .ft B dup2 src dst .ft R duplicates .ft B src .ft R to .ft B dst .ft R , closing .ft B dst .ft R if already opened\&. See .ft B Unix\&.set_close_on_exec .ft R for documentation on the .ft B cloexec .ft R optional argument\&. .sp .I val set_nonblock : .B file_descr -> unit .sp 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 .ft B EAGAIN .ft R or .ft B EWOULDBLOCK .ft R error instead of blocking; writing on a descriptor on which there is temporarily no room for writing also raises .ft B EAGAIN .ft R or .ft B EWOULDBLOCK .ft R \&. .sp .I val clear_nonblock : .B file_descr -> unit .sp Clear the ``non\-blocking\&'\&' flag on the given descriptor\&. See .ft B Unix\&.set_nonblock .ft R \&. .sp .I val set_close_on_exec : .B file_descr -> unit .sp 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 .ft B exec .ft R , .ft B create_process .ft R and .ft B open_process .ft R functions\&. .sp 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\&. .sp The best way to set a file descriptor ``close\-on\-exec\&'\&' is to create it in this state\&. To this end, the .ft B openfile .ft R function has .ft B O_CLOEXEC .ft R and .ft B O_KEEPEXEC .ft R 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 .ft B ?cloexec:bool .ft R to indicate whether the file descriptor should be created in ``close\-on\-exec\&'\&' mode (by writing .ft B ~cloexec:true .ft R ) or in ``keep\-on\-exec\&'\&' mode (by writing .ft B ~cloexec:false .ft R )\&. For historical reasons, the default file descriptor creation mode is ``keep\-on\-exec\&'\&', if no .ft B cloexec .ft R optional argument is given\&. This is not a safe default, hence it is highly recommended to pass explicit .ft B cloexec .ft R arguments to operations that create file descriptors\&. .sp The .ft B cloexec .ft R optional arguments and the .ft B O_KEEPEXEC .ft R 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 .ft B set_close_on_exec .ft R 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 .ft B set_close_on_exec .ft R completes\&. If another thread spawns another program during this window, the descriptor will leak, as it is still in the ``keep\-on\-exec\&'\&' mode\&. .sp Regarding the atomicity guarantees given by .ft B ~cloexec:true .ft R or by the use of the .ft B O_CLOEXEC .ft R 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\&. .sp .I val clear_close_on_exec : .B file_descr -> unit .sp Clear the ``close\-on\-exec\&'\&' flag on the given descriptor\&. See .ft B Unix\&.set_close_on_exec .ft R \&. .sp .PP .SS Directories .PP .I val mkdir : .B string -> file_perm -> unit .sp Create a directory with the given permissions (see .ft B Unix\&.umask .ft R )\&. .sp .I val rmdir : .B string -> unit .sp Remove an empty directory\&. .sp .I val chdir : .B string -> unit .sp Change the process working directory\&. .sp .I val getcwd : .B unit -> string .sp Return the name of the current working directory\&. .sp .I val chroot : .B string -> unit .sp Change the process root directory\&. .sp .B "Raises Invalid_argument" on Windows .sp .I type dir_handle .sp The type of descriptors over opened directories\&. .sp .I val opendir : .B string -> dir_handle .sp Open a descriptor on a directory .sp .I val readdir : .B dir_handle -> string .sp Return the next entry in a directory\&. .sp .B "Raises End_of_file" when the end of the directory has been reached\&. .sp .I val rewinddir : .B dir_handle -> unit .sp Reposition the descriptor to the beginning of the directory .sp .I val closedir : .B dir_handle -> unit .sp Close a directory descriptor\&. .sp .PP .SS Pipes and redirections .PP .I val pipe : .B ?cloexec:bool -> unit -> file_descr * file_descr .sp 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 .ft B Unix\&.set_close_on_exec .ft R for documentation on the .ft B cloexec .ft R optional argument\&. .sp .I val mkfifo : .B string -> file_perm -> unit .sp Create a named pipe with the given permissions (see .ft B Unix\&.umask .ft R )\&. .sp .B "Raises Invalid_argument" on Windows .sp .PP .SS High-level process and redirection management .PP .I val create_process : .B string -> .B string array -> file_descr -> file_descr -> file_descr -> int .sp .ft B create_process prog args stdin stdout stderr .ft R creates a new process that executes the program in file .ft B prog .ft R , with arguments .ft B args .ft R \&. Note that the first argument, .ft B args\&.(0) .ft R , is by convention the filename of the program being executed, just like .ft B Sys\&.argv\&.(0) .ft R \&. 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 .ft B stdin .ft R , .ft B stdout .ft R and .ft B stderr .ft R \&. Passing e\&.g\&. .ft B Unix\&.stdout .ft R for .ft B stdout .ft R prevents the redirection and causes the new process to have the same standard output as the current process\&. The executable file .ft B prog .ft R is searched in the path\&. The new process has the same environment as the current process\&. .sp .I val create_process_env : .B string -> .B string array -> .B string array -> file_descr -> file_descr -> file_descr -> int .sp .ft B create_process_env prog args env stdin stdout stderr .ft R works as .ft B Unix\&.create_process .ft R , except that the extra argument .ft B env .ft R specifies the environment passed to the program\&. .sp .I val open_process_in : .B string -> in_channel .sp 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 .ft B /bin/sh .ft R (or .ft B cmd\&.exe .ft R on Windows), cf\&. .ft B Unix\&.system .ft R \&. The .ft B Filename\&.quote_command .ft R 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, .ft B Unix\&.open_process_args_in .ft R can be used as a more robust and more efficient alternative to .ft B Unix\&.open_process_in .ft R \&. .sp .I val open_process_out : .B string -> out_channel .sp Same as .ft B Unix\&.open_process_in .ft R , 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 .ft B flush .ft R at the right times to ensure correct synchronization\&. If the command does not need to be run through the shell, .ft B Unix\&.open_process_args_out .ft R can be used instead of .ft B Unix\&.open_process_out .ft R \&. .sp .I val open_process : .B string -> in_channel * out_channel .sp Same as .ft B Unix\&.open_process_out .ft R , 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, .ft B Unix\&.open_process_args .ft R can be used instead of .ft B Unix\&.open_process .ft R \&. .sp .I val open_process_full : .B string -> .B string array -> in_channel * out_channel * in_channel .sp Similar to .ft B Unix\&.open_process .ft R , 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, .ft B Unix\&.open_process_args_full .ft R can be used instead of .ft B Unix\&.open_process_full .ft R \&. .sp .I val open_process_args : .B string -> string array -> in_channel * out_channel .sp .ft B open_process_args prog args .ft R runs the program .ft B prog .ft R with arguments .ft B args .ft R \&. Note that the first argument, .ft B args\&.(0) .ft R , is by convention the filename of the program being executed, just like .ft B Sys\&.argv\&.(0) .ft R \&. 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\&. .sp Warning: writes on output channels are buffered, hence be careful to call .ft B flush .ft R at the right times to ensure correct synchronization\&. .sp The executable file .ft B prog .ft R is searched for in the path\&. This behaviour changed in 4\&.12; previously .ft B prog .ft R was looked up only in the current directory\&. .sp The new process has the same environment as the current process\&. .sp .B "Since" 4.08 .sp .I val open_process_args_in : .B string -> string array -> in_channel .sp Same as .ft B Unix\&.open_process_args .ft R , but redirects only the standard output of the new process\&. .sp .B "Since" 4.08 .sp .I val open_process_args_out : .B string -> string array -> out_channel .sp Same as .ft B Unix\&.open_process_args .ft R , but redirects only the standard input of the new process\&. .sp .B "Since" 4.08 .sp .I val open_process_args_full : .B string -> .B string array -> .B string array -> in_channel * out_channel * in_channel .sp Similar to .ft B Unix\&.open_process_args .ft R , 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\&. .sp .B "Since" 4.08 .sp .I val process_in_pid : .B in_channel -> int .sp Return the pid of a process opened via .ft B Unix\&.open_process_args_in .ft R or the pid of the shell opened via .ft B Unix\&.open_process_in .ft R \&. .sp .B "Since" 4.08 (4.12 in UnixLabels) .sp .I val process_out_pid : .B out_channel -> int .sp Return the pid of a process opened via .ft B Unix\&.open_process_args_out .ft R or the pid of the shell opened via .ft B Unix\&.open_process_out .ft R \&. .sp .B "Since" 4.08 (4.12 in UnixLabels) .sp .I val process_pid : .B in_channel * out_channel -> int .sp Return the pid of a process opened via .ft B Unix\&.open_process_args .ft R or the pid of the shell opened via .ft B Unix\&.open_process_args .ft R \&. .sp .B "Since" 4.08 (4.12 in UnixLabels) .sp .I val process_full_pid : .B in_channel * out_channel * in_channel -> int .sp Return the pid of a process opened via .ft B Unix\&.open_process_args_full .ft R or the pid of the shell opened via .ft B Unix\&.open_process_full .ft R \&. .sp .B "Since" 4.08 (4.12 in UnixLabels) .sp .I val close_process_in : .B in_channel -> process_status .sp Close channels opened by .ft B Unix\&.open_process_in .ft R , wait for the associated command to terminate, and return its termination status\&. .sp .I val close_process_out : .B out_channel -> process_status .sp Close channels opened by .ft B Unix\&.open_process_out .ft R , wait for the associated command to terminate, and return its termination status\&. .sp .I val close_process : .B in_channel * out_channel -> process_status .sp Close channels opened by .ft B Unix\&.open_process .ft R , wait for the associated command to terminate, and return its termination status\&. .sp .I val close_process_full : .B in_channel * out_channel * in_channel -> .B process_status .sp Close channels opened by .ft B Unix\&.open_process_full .ft R , wait for the associated command to terminate, and return its termination status\&. .sp .PP .SS Symbolic links .PP .I val symlink : .B ?to_dir:bool -> string -> string -> unit .sp .ft B symlink ?to_dir src dst .ft R creates the file .ft B dst .ft R as a symbolic link to the file .ft B src .ft R \&. On Windows, .ft B ~to_dir .ft R indicates if the symbolic link points to a directory or a file; if omitted, .ft B symlink .ft R examines .ft B src .ft R using .ft B stat .ft R and picks appropriately, if .ft B src .ft R does not exist then .ft B false .ft R is assumed (for this reason, it is recommended that the .ft B ~to_dir .ft R parameter be specified in new code)\&. On Unix, .ft B ~to_dir .ft R is ignored\&. .sp Windows symbolic links are available in Windows Vista onwards\&. There are some important differences between Windows symlinks and their POSIX counterparts\&. .sp 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)\&. .sp When symbolic links are created to existing targets, this distinction doesn\&'t matter and .ft B symlink .ft R will automatically create the correct kind of symbolic link\&. The distinction matters when a symbolic link is created to a non\-existent target\&. .sp 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\&. .sp .ft B Unix\&.has_symlink .ft R can be used to check that a process is able to create symbolic links\&. .sp .I val has_symlink : .B unit -> bool .sp Returns .ft B true .ft R 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\&. .sp .B "Since" 4.03 .sp .I val readlink : .B string -> string .sp Read the contents of a symbolic link\&. .sp .PP .SS Polling .PP .I val select : .B file_descr list -> .B file_descr list -> .B file_descr list -> .B float -> file_descr list * file_descr list * file_descr list .sp 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)\&. .sp .PP .SS Locking .PP .I type 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 *) .sp Commands for .ft B Unix\&.lockf .ft R \&. .sp .I val lockf : .B file_descr -> lock_command -> int -> unit .sp .ft B lockf fd mode len .ft R puts a lock on a region of the file opened as .ft B fd .ft R \&. The region starts at the current read/write position for .ft B fd .ft R (as set by .ft B Unix\&.lseek .ft R ), and extends .ft B len .ft R bytes forward if .ft B len .ft R is positive, .ft B len .ft R bytes backwards if .ft B len .ft R is negative, or to the end of the file if .ft B len .ft R 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\&. .sp The .ft B F_LOCK .ft R and .ft B F_TLOCK .ft R commands attempts to put a write lock on the specified region\&. The .ft B F_RLOCK .ft R and .ft B F_TRLOCK .ft R 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, .ft B F_LOCK .ft R and .ft B F_RLOCK .ft R block until these locks are removed, while .ft B F_TLOCK .ft R and .ft B F_TRLOCK .ft R fail immediately with an exception\&. The .ft B F_ULOCK .ft R removes whatever locks the current process has on the specified region\&. Finally, the .ft B F_TEST .ft R 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\&. .sp 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\&. .sp .PP .SS Signals Note: installation of signal handlers is performed via the functions .ft B Sys\&.signal .ft R and .ft B Sys\&.set_signal .ft R \&. .PP .I val kill : .B int -> int -> unit .sp .ft B kill pid signal .ft R sends signal number .ft B signal .ft R to the process with id .ft B pid .ft R \&. .sp On Windows: only the .ft B Sys\&.sigkill .ft R signal is emulated\&. .sp .I type sigprocmask_command = | SIG_SETMASK | SIG_BLOCK | SIG_UNBLOCK .sp .sp .I val sigprocmask : .B sigprocmask_command -> int list -> int list .sp .ft B sigprocmask mode sigs .ft R changes the set of blocked signals\&. If .ft B mode .ft R is .ft B SIG_SETMASK .ft R , blocked signals are set to those in the list .ft B sigs .ft R \&. If .ft B mode .ft R is .ft B SIG_BLOCK .ft R , the signals in .ft B sigs .ft R are added to the set of blocked signals\&. If .ft B mode .ft R is .ft B SIG_UNBLOCK .ft R , the signals in .ft B sigs .ft R are removed from the set of blocked signals\&. .ft B sigprocmask .ft R returns the set of previously blocked signals\&. .sp When the systhreads version of the .ft B Thread .ft R module is loaded, this function redirects to .ft B Thread\&.sigmask .ft R \&. I\&.e\&., .ft B sigprocmask .ft R only changes the mask of the current thread\&. .sp .B "Raises Invalid_argument" on Windows (no inter\-process signals on Windows) .sp .I val sigpending : .B unit -> int list .sp Return the set of blocked signals that are currently pending\&. .sp .B "Raises Invalid_argument" on Windows (no inter\-process signals on Windows) .sp .I val sigsuspend : .B int list -> unit .sp .ft B sigsuspend sigs .ft R atomically sets the blocked signals to .ft B sigs .ft R and waits for a non\-ignored, non\-blocked signal to be delivered\&. On return, the blocked signals are reset to their initial value\&. .sp .B "Raises Invalid_argument" on Windows (no inter\-process signals on Windows) .sp .I val pause : .B unit -> unit .sp Wait until a non\-ignored, non\-blocked signal is delivered\&. .sp .B "Raises Invalid_argument" on Windows (no inter\-process signals on Windows) .sp .PP .SS Time functions .PP .I type process_times = { tms_utime : .B float ; (* User time for the process *) tms_stime : .B float ; (* System time for the process *) tms_cutime : .B float ; (* User time for the children processes *) tms_cstime : .B float ; (* System time for the children processes *) } .sp The execution times (CPU times) of a process\&. .sp .I type tm = { tm_sec : .B int ; (* Seconds 0\&.\&.60 *) tm_min : .B int ; (* Minutes 0\&.\&.59 *) tm_hour : .B int ; (* Hours 0\&.\&.23 *) tm_mday : .B int ; (* Day of month 1\&.\&.31 *) tm_mon : .B int ; (* Month of year 0\&.\&.11 *) tm_year : .B int ; (* Year \- 1900 *) tm_wday : .B int ; (* Day of week (Sunday is 0) *) tm_yday : .B int ; (* Day of year 0\&.\&.365 *) tm_isdst : .B bool ; (* Daylight time savings in effect *) } .sp The type representing wallclock time and calendar date\&. .sp .I val time : .B unit -> float .sp Return the current time since 00:00:00 GMT, Jan\&. 1, 1970, in seconds\&. .sp .I val gettimeofday : .B unit -> float .sp Same as .ft B Unix\&.time .ft R , but with resolution better than 1 second\&. .sp .I val gmtime : .B float -> tm .sp Convert a time in seconds, as returned by .ft B Unix\&.time .ft R , into a date and a time\&. Assumes UTC (Coordinated Universal Time), also known as GMT\&. To perform the inverse conversion, set the TZ environment variable to "UTC", use .ft B Unix\&.mktime .ft R , and then restore the original value of TZ\&. .sp .I val localtime : .B float -> tm .sp Convert a time in seconds, as returned by .ft B Unix\&.time .ft R , into a date and a time\&. Assumes the local time zone\&. The function performing the inverse conversion is .ft B Unix\&.mktime .ft R \&. .sp .I val mktime : .B tm -> float * tm .sp Convert a date and time, specified by the .ft B tm .ft R argument, into a time in seconds, as returned by .ft B Unix\&.time .ft R \&. The .ft B tm_isdst .ft R , .ft B tm_wday .ft R and .ft B tm_yday .ft R fields of .ft B tm .ft R are ignored\&. Also return a normalized copy of the given .ft B tm .ft R record, with the .ft B tm_wday .ft R , .ft B tm_yday .ft R , and .ft B tm_isdst .ft R fields recomputed from the other fields, and the other fields normalized (so that, e\&.g\&., 40 October is changed into 9 November)\&. The .ft B tm .ft R argument is interpreted in the local time zone\&. .sp .I val alarm : .B int -> int .sp Schedule a .ft B SIGALRM .ft R signal after the given number of seconds\&. .sp .B "Raises Invalid_argument" on Windows .sp .I val sleep : .B int -> unit .sp Stop execution for the given number of seconds\&. .sp .I val sleepf : .B float -> unit .sp Stop execution for the given number of seconds\&. Like .ft B sleep .ft R , but fractions of seconds are supported\&. .sp .B "Since" 4.03 (4.12 in UnixLabels) .sp .I val times : .B unit -> process_times .sp Return the execution times of the process\&. .sp On Windows: partially implemented, will not report timings for child processes\&. .sp .I val utimes : .B string -> float -> float -> unit .sp 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 .ft B 0\&.0 .ft R , the access and last modification times are both set to the current time\&. .sp .I type interval_timer = | ITIMER_REAL (* decrements in real time, and sends the signal .ft B SIGALRM .ft R when expired\&. *) | ITIMER_VIRTUAL (* decrements in process virtual time, and sends .ft B SIGVTALRM .ft R 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 .ft B SIGPROF .ft R when expired\&. *) .sp The three kinds of interval timers\&. .sp .I type interval_timer_status = { it_interval : .B float ; (* Period *) it_value : .B float ; (* Current value of the timer *) } .sp The type describing the status of an interval timer .sp .I val getitimer : .B interval_timer -> interval_timer_status .sp Return the current status of the given interval timer\&. .sp .B "Raises Invalid_argument" on Windows .sp .I val setitimer : .B interval_timer -> .B interval_timer_status -> interval_timer_status .sp .ft B setitimer t s .ft R sets the interval timer .ft B t .ft R and returns its previous status\&. The .ft B s .ft R argument is interpreted as follows: .ft B s\&.it_value .ft R , if nonzero, is the time to the next timer expiration; .ft B s\&.it_interval .ft R , if nonzero, specifies a value to be used in reloading .ft B it_value .ft R when the timer expires\&. Setting .ft B s\&.it_value .ft R to zero disables the timer\&. Setting .ft B s\&.it_interval .ft R to zero causes the timer to be disabled after its next expiration\&. .sp .B "Raises Invalid_argument" on Windows .sp .PP .SS User id, group id .PP .I val getuid : .B unit -> int .sp Return the user id of the user executing the process\&. .sp On Windows: always returns .ft B 1 .ft R \&. .sp .I val geteuid : .B unit -> int .sp Return the effective user id under which the process runs\&. .sp On Windows: always returns .ft B 1 .ft R \&. .sp .I val setuid : .B int -> unit .sp Set the real user id and effective user id for the process\&. .sp .B "Raises Invalid_argument" on Windows .sp .I val getgid : .B unit -> int .sp Return the group id of the user executing the process\&. .sp On Windows: always returns .ft B 1 .ft R \&. .sp .I val getegid : .B unit -> int .sp Return the effective group id under which the process runs\&. .sp On Windows: always returns .ft B 1 .ft R \&. .sp .I val setgid : .B int -> unit .sp Set the real group id and effective group id for the process\&. .sp .B "Raises Invalid_argument" on Windows .sp .I val getgroups : .B unit -> int array .sp Return the list of groups to which the user executing the process belongs\&. .sp On Windows: always returns .ft B [|1|] .ft R \&. .sp .I val setgroups : .B int array -> unit .sp .ft B setgroups groups .ft R sets the supplementary group IDs for the calling process\&. Appropriate privileges are required\&. .sp .B "Raises Invalid_argument" on Windows .sp .I val initgroups : .B string -> int -> unit .sp .ft B initgroups user group .ft R initializes the group access list by reading the group database /etc/group and using all groups of which .ft B user .ft R is a member\&. The additional group .ft B group .ft R is also added to the list\&. .sp .B "Raises Invalid_argument" on Windows .sp .I type passwd_entry = { pw_name : .B string ; pw_passwd : .B string ; pw_uid : .B int ; pw_gid : .B int ; pw_gecos : .B string ; pw_dir : .B string ; pw_shell : .B string ; } .sp Structure of entries in the .ft B passwd .ft R database\&. .sp .I type group_entry = { gr_name : .B string ; gr_passwd : .B string ; gr_gid : .B int ; gr_mem : .B string array ; } .sp Structure of entries in the .ft B groups .ft R database\&. .sp .I val getlogin : .B unit -> string .sp Return the login name of the user executing the process\&. .sp .I val getpwnam : .B string -> passwd_entry .sp Find an entry in .ft B passwd .ft R with the given name\&. .sp .B "Raises Not_found" if no such entry exists, or always on Windows\&. .sp .I val getgrnam : .B string -> group_entry .sp Find an entry in .ft B group .ft R with the given name\&. .sp .B "Raises Not_found" if no such entry exists, or always on Windows\&. .sp .I val getpwuid : .B int -> passwd_entry .sp Find an entry in .ft B passwd .ft R with the given user id\&. .sp .B "Raises Not_found" if no such entry exists, or always on Windows\&. .sp .I val getgrgid : .B int -> group_entry .sp Find an entry in .ft B group .ft R with the given group id\&. .sp .B "Raises Not_found" if no such entry exists, or always on Windows\&. .sp .PP .SS Internet addresses .PP .I type inet_addr .sp The abstract type of Internet addresses\&. .sp .I val inet_addr_of_string : .B string -> inet_addr .sp Conversion from the printable representation of an Internet address to its internal representation\&. The argument string consists of 4 numbers separated by periods ( .ft B XXX\&.YYY\&.ZZZ\&.TTT .ft R ) for IPv4 addresses, and up to 8 numbers separated by colons for IPv6 addresses\&. .sp .B "Raises Failure" when given a string that does not match these formats\&. .sp .I val string_of_inet_addr : .B inet_addr -> string .sp Return the printable representation of the given Internet address\&. See .ft B Unix\&.inet_addr_of_string .ft R for a description of the printable representation\&. .sp .I val inet_addr_any : .B inet_addr .sp A special IPv4 address, for use only with .ft B bind .ft R , representing all the Internet addresses that the host machine possesses\&. .sp .I val inet_addr_loopback : .B inet_addr .sp A special IPv4 address representing the host machine ( .ft B 127\&.0\&.0\&.1 .ft R )\&. .sp .I val inet6_addr_any : .B inet_addr .sp A special IPv6 address, for use only with .ft B bind .ft R , representing all the Internet addresses that the host machine possesses\&. .sp .I val inet6_addr_loopback : .B inet_addr .sp A special IPv6 address representing the host machine ( .ft B ::1 .ft R )\&. .sp .I val is_inet6_addr : .B inet_addr -> bool .sp Whether the given .ft B inet_addr .ft R is an IPv6 address\&. .sp .B "Since" 4.12 .sp .PP .SS Sockets .PP .I type socket_domain = | PF_UNIX (* Unix domain *) | PF_INET (* Internet domain (IPv4) *) | PF_INET6 (* Internet domain (IPv6) *) .sp The type of socket domains\&. Not all platforms support IPv6 sockets (type .ft B PF_INET6 .ft R )\&. .sp On Windows: .ft B PF_UNIX .ft R supported since 4\&.14\&.0 on Windows 10 1803 and later\&. .sp .I type socket_type = | SOCK_STREAM (* Stream socket *) | SOCK_DGRAM (* Datagram socket *) | SOCK_RAW (* Raw socket *) | SOCK_SEQPACKET (* Sequenced packets socket *) .sp The type of socket kinds, specifying the semantics of communications\&. .ft B SOCK_SEQPACKET .ft R is included for completeness, but is rarely supported by the OS, and needs system calls that are not available in this library\&. .sp .I type sockaddr = | ADDR_UNIX .B of .B string | ADDR_INET .B of .B inet_addr * int .sp The type of socket addresses\&. .ft B ADDR_UNIX name .ft R is a socket address in the Unix domain; .ft B name .ft R is a file name in the file system\&. .ft B ADDR_INET(addr,port) .ft R is a socket address in the Internet domain; .ft B addr .ft R is the Internet address of the machine, and .ft B port .ft R is the port number\&. .sp .I val socket : .B ?cloexec:bool -> .B socket_domain -> socket_type -> int -> file_descr .sp 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 .ft B Unix\&.set_close_on_exec .ft R for documentation on the .ft B cloexec .ft R optional argument\&. .sp .I val domain_of_sockaddr : .B sockaddr -> socket_domain .sp Return the socket domain adequate for the given socket address\&. .sp .I val socketpair : .B ?cloexec:bool -> .B socket_domain -> .B socket_type -> int -> file_descr * file_descr .sp Create a pair of unnamed sockets, connected together\&. See .ft B Unix\&.set_close_on_exec .ft R for documentation on the .ft B cloexec .ft R optional argument\&. .sp .I val accept : .B ?cloexec:bool -> file_descr -> file_descr * sockaddr .sp 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 .ft B Unix\&.set_close_on_exec .ft R for documentation on the .ft B cloexec .ft R optional argument\&. .sp .I val bind : .B file_descr -> sockaddr -> unit .sp Bind a socket to an address\&. .sp .I val connect : .B file_descr -> sockaddr -> unit .sp Connect a socket to an address\&. .sp .I val listen : .B file_descr -> int -> unit .sp Set up a socket for receiving connection requests\&. The integer argument is the maximal number of pending requests\&. .sp .I type shutdown_command = | SHUTDOWN_RECEIVE (* Close for receiving *) | SHUTDOWN_SEND (* Close for sending *) | SHUTDOWN_ALL (* Close both *) .sp The type of commands for .ft B shutdown .ft R \&. .sp .I val shutdown : .B file_descr -> shutdown_command -> unit .sp Shutdown a socket connection\&. .ft B SHUTDOWN_SEND .ft R as second argument causes reads on the other end of the connection to return an end\-of\-file condition\&. .ft B SHUTDOWN_RECEIVE .ft R causes writes on the other end of the connection to return a closed pipe condition ( .ft B SIGPIPE .ft R signal)\&. .sp .I val getsockname : .B file_descr -> sockaddr .sp Return the address of the given socket\&. .sp .I val getpeername : .B file_descr -> sockaddr .sp Return the address of the host connected to the given socket\&. .sp .I type msg_flag = | MSG_OOB | MSG_DONTROUTE | MSG_PEEK .sp The flags for .ft B Unix\&.recv .ft R , .ft B Unix\&.recvfrom .ft R , .ft B Unix\&.send .ft R and .ft B Unix\&.sendto .ft R \&. .sp .I val recv : .B file_descr -> bytes -> int -> int -> msg_flag list -> int .sp Receive data from a connected socket\&. .sp .I val recvfrom : .B file_descr -> .B bytes -> int -> int -> msg_flag list -> int * sockaddr .sp Receive data from an unconnected socket\&. .sp .I val send : .B file_descr -> bytes -> int -> int -> msg_flag list -> int .sp Send data over a connected socket\&. .sp .I val send_substring : .B file_descr -> string -> int -> int -> msg_flag list -> int .sp Same as .ft B send .ft R , but take the data from a string instead of a byte sequence\&. .sp .B "Since" 4.02 .sp .I val sendto : .B file_descr -> .B bytes -> int -> int -> msg_flag list -> sockaddr -> int .sp Send data over an unconnected socket\&. .sp .I val sendto_substring : .B file_descr -> .B string -> int -> int -> msg_flag list -> sockaddr -> int .sp Same as .ft B sendto .ft R , but take the data from a string instead of a byte sequence\&. .sp .B "Since" 4.02 .sp .PP .SS Socket options .PP .I type 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\&. .sp .B "Since" 4.12. *) .sp The socket options that can be consulted with .ft B Unix\&.getsockopt .ft R and modified with .ft B Unix\&.setsockopt .ft R \&. These options have a boolean ( .ft B true .ft R / .ft B false .ft R ) value\&. .sp .I type socket_int_option = | SO_SNDBUF (* Size of send buffer *) | SO_RCVBUF (* Size of received buffer *) | SO_ERROR (* .B "Deprecated." Use Unix\&.getsockopt_error instead\&. .sp Deprecated\&. Use .ft B Unix\&.getsockopt_error .ft R instead\&. *) | SO_TYPE (* Report the socket type *) | SO_RCVLOWAT (* Minimum number of bytes to process for input operations *) | SO_SNDLOWAT (* Minimum number of bytes to process for output operations *) .sp The socket options that can be consulted with .ft B Unix\&.getsockopt_int .ft R and modified with .ft B Unix\&.setsockopt_int .ft R \&. These options have an integer value\&. .sp .I type socket_optint_option = | SO_LINGER (* Whether to linger on closed connections that have data present, and for how long (in seconds) *) .sp The socket options that can be consulted with .ft B Unix\&.getsockopt_optint .ft R and modified with .ft B Unix\&.setsockopt_optint .ft R \&. These options have a value of type .ft B int option .ft R , with .ft B None .ft R meaning ``disabled\&'\&'\&. .sp .I type socket_float_option = | SO_RCVTIMEO (* Timeout for input operations *) | SO_SNDTIMEO (* Timeout for output operations *) .sp The socket options that can be consulted with .ft B Unix\&.getsockopt_float .ft R and modified with .ft B Unix\&.setsockopt_float .ft R \&. These options have a floating\-point value representing a time in seconds\&. The value 0 means infinite timeout\&. .sp .I val getsockopt : .B file_descr -> socket_bool_option -> bool .sp Return the current status of a boolean\-valued option in the given socket\&. .sp .I val setsockopt : .B file_descr -> socket_bool_option -> bool -> unit .sp Set or clear a boolean\-valued option in the given socket\&. .sp .I val getsockopt_int : .B file_descr -> socket_int_option -> int .sp Same as .ft B Unix\&.getsockopt .ft R for an integer\-valued socket option\&. .sp .I val setsockopt_int : .B file_descr -> socket_int_option -> int -> unit .sp Same as .ft B Unix\&.setsockopt .ft R for an integer\-valued socket option\&. .sp .I val getsockopt_optint : .B file_descr -> socket_optint_option -> int option .sp Same as .ft B Unix\&.getsockopt .ft R for a socket option whose value is an .ft B int option .ft R \&. .sp .I val setsockopt_optint : .B file_descr -> socket_optint_option -> int option -> unit .sp Same as .ft B Unix\&.setsockopt .ft R for a socket option whose value is an .ft B int option .ft R \&. .sp .I val getsockopt_float : .B file_descr -> socket_float_option -> float .sp Same as .ft B Unix\&.getsockopt .ft R for a socket option whose value is a floating\-point number\&. .sp .I val setsockopt_float : .B file_descr -> socket_float_option -> float -> unit .sp Same as .ft B Unix\&.setsockopt .ft R for a socket option whose value is a floating\-point number\&. .sp .I val getsockopt_error : .B file_descr -> error option .sp Return the error condition associated with the given socket, and clear it\&. .sp .PP .SS High-level network connection functions .PP .I val open_connection : .B sockaddr -> in_channel * out_channel .sp Connect to a server at the given address\&. Return a pair of buffered channels connected to the server\&. Remember to call .ft B flush .ft R on the output channel at the right times to ensure correct synchronization\&. .sp The two channels returned by .ft B open_connection .ft R share a descriptor to a socket\&. Therefore, when the connection is over, you should call .ft B close_out .ft R on the output channel, which will also close the underlying socket\&. Do not call .ft B close_in .ft R on the input channel; it will be collected by the GC eventually\&. .sp .I val shutdown_connection : .B in_channel -> unit .sp ``Shut down\&'\&' a connection established with .ft B Unix\&.open_connection .ft R ; 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 .ft B Unix\&.open_connection .ft R for how to close them once the connection is over\&. .sp .I val establish_server : .B (in_channel -> out_channel -> unit) -> sockaddr -> unit .sp 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 .ft B Unix\&.establish_server .ft R never returns normally\&. .sp 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 .ft B close_out .ft R and leave the input channel unclosed, for reasons explained in .ft B Unix\&.in_channel_of_descr .ft R \&. .sp .B "Raises Invalid_argument" on Windows\&. Use threads instead\&. .sp .PP .SS Host and protocol databases .PP .I type host_entry = { h_name : .B string ; h_aliases : .B string array ; h_addrtype : .B socket_domain ; h_addr_list : .B inet_addr array ; } .sp Structure of entries in the .ft B hosts .ft R database\&. .sp .I type protocol_entry = { p_name : .B string ; p_aliases : .B string array ; p_proto : .B int ; } .sp Structure of entries in the .ft B protocols .ft R database\&. .sp .I type service_entry = { s_name : .B string ; s_aliases : .B string array ; s_port : .B int ; s_proto : .B string ; } .sp Structure of entries in the .ft B services .ft R database\&. .sp .I val gethostname : .B unit -> string .sp Return the name of the local host\&. .sp .I val gethostbyname : .B string -> host_entry .sp Find an entry in .ft B hosts .ft R with the given name\&. .sp .B "Raises Not_found" if no such entry exists\&. .sp .I val gethostbyaddr : .B inet_addr -> host_entry .sp Find an entry in .ft B hosts .ft R with the given address\&. .sp .B "Raises Not_found" if no such entry exists\&. .sp .I val getprotobyname : .B string -> protocol_entry .sp Find an entry in .ft B protocols .ft R with the given name\&. .sp .B "Raises Not_found" if no such entry exists\&. .sp .I val getprotobynumber : .B int -> protocol_entry .sp Find an entry in .ft B protocols .ft R with the given protocol number\&. .sp .B "Raises Not_found" if no such entry exists\&. .sp .I val getservbyname : .B string -> string -> service_entry .sp Find an entry in .ft B services .ft R with the given name\&. .sp .B "Raises Not_found" if no such entry exists\&. .sp .I val getservbyport : .B int -> string -> service_entry .sp Find an entry in .ft B services .ft R with the given service number\&. .sp .B "Raises Not_found" if no such entry exists\&. .sp .I type addr_info = { ai_family : .B socket_domain ; (* Socket domain *) ai_socktype : .B socket_type ; (* Socket type *) ai_protocol : .B int ; (* Socket protocol number *) ai_addr : .B sockaddr ; (* Address *) ai_canonname : .B string ; (* Canonical host name *) } .sp Address information returned by .ft B Unix\&.getaddrinfo .ft R \&. .sp .I type getaddrinfo_option = | AI_FAMILY .B of .B socket_domain .I " " (* Impose the given socket domain *) | AI_SOCKTYPE .B of .B socket_type .I " " (* Impose the given socket type *) | AI_PROTOCOL .B of .B int .I " " (* Impose the given protocol *) | AI_NUMERICHOST (* Do not call name resolver, expect numeric IP address *) | AI_CANONNAME (* Fill the .ft B ai_canonname .ft R field of the result *) | AI_PASSIVE (* Set address to ``any\&'\&' address for use with .ft B Unix\&.bind .ft R *) .sp Options to .ft B Unix\&.getaddrinfo .ft R \&. .sp .I val getaddrinfo : .B string -> string -> getaddrinfo_option list -> addr_info list .sp .ft B getaddrinfo host service opts .ft R returns a list of .ft B Unix\&.addr_info .ft R 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 .ft B opts .ft R cannot be satisfied\&. .sp .ft B host .ft R is either a host name or the string representation of an IP address\&. .ft B host .ft R can be given as the empty string; in this case, the ``any\&'\&' address or the ``loopback\&'\&' address are used, depending whether .ft B opts .ft R contains .ft B AI_PASSIVE .ft R \&. .ft B service .ft R is either a service name or the string representation of a port number\&. .ft B service .ft R can be given as the empty string; in this case, the port field of the returned addresses is set to 0\&. .ft B opts .ft R 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)\&. .sp .I type name_info = { ni_hostname : .B string ; (* Name or IP address of host *) ni_service : .B string ; (* Name of service or port number *) } .sp Host and service information returned by .ft B Unix\&.getnameinfo .ft R \&. .sp .I type getnameinfo_option = | NI_NOFQDN (* Do not qualify local host names *) | NI_NUMERICHOST (* Always return host as IP address *) | NI_NAMEREQD (* Fail if host name cannot be determined *) | NI_NUMERICSERV (* Always return service as port number *) | NI_DGRAM (* Consider the service as UDP\-based instead of the default TCP *) .sp Options to .ft B Unix\&.getnameinfo .ft R \&. .sp .I val getnameinfo : .B sockaddr -> getnameinfo_option list -> name_info .sp .ft B getnameinfo addr opts .ft R returns the host name and service name corresponding to the socket address .ft B addr .ft R \&. .ft B opts .ft R is a possibly empty list of options that governs how these names are obtained\&. .sp .B "Raises Not_found" if an error occurs\&. .sp .PP .SS Terminal interface .PP .PP The following functions implement the POSIX standard terminal interface\&. They provide control over asynchronous communication ports and pseudo\-terminals\&. Refer to the .ft B termios .ft R man page for a complete description\&. .PP .I type terminal_io = { .B mutable c_ignbrk : .B bool ; (* Ignore the break condition\&. *) .B mutable c_brkint : .B bool ; (* Signal interrupt on break condition\&. *) .B mutable c_ignpar : .B bool ; (* Ignore characters with parity errors\&. *) .B mutable c_parmrk : .B bool ; (* Mark parity errors\&. *) .B mutable c_inpck : .B bool ; (* Enable parity check on input\&. *) .B mutable c_istrip : .B bool ; (* Strip 8th bit on input characters\&. *) .B mutable c_inlcr : .B bool ; (* Map NL to CR on input\&. *) .B mutable c_igncr : .B bool ; (* Ignore CR on input\&. *) .B mutable c_icrnl : .B bool ; (* Map CR to NL on input\&. *) .B mutable c_ixon : .B bool ; (* Recognize XON/XOFF characters on input\&. *) .B mutable c_ixoff : .B bool ; (* Emit XON/XOFF chars to control input flow\&. *) .B mutable c_opost : .B bool ; (* Enable output processing\&. *) .B mutable c_obaud : .B int ; (* Output baud rate (0 means close connection)\&. *) .B mutable c_ibaud : .B int ; (* Input baud rate\&. *) .B mutable c_csize : .B int ; (* Number of bits per character (5\-8)\&. *) .B mutable c_cstopb : .B int ; (* Number of stop bits (1\-2)\&. *) .B mutable c_cread : .B bool ; (* Reception is enabled\&. *) .B mutable c_parenb : .B bool ; (* Enable parity generation and detection\&. *) .B mutable c_parodd : .B bool ; (* Specify odd parity instead of even\&. *) .B mutable c_hupcl : .B bool ; (* Hang up on last close\&. *) .B mutable c_clocal : .B bool ; (* Ignore modem status lines\&. *) .B mutable c_isig : .B bool ; (* Generate signal on INTR, QUIT, SUSP\&. *) .B mutable c_icanon : .B bool ; (* Enable canonical processing (line buffering and editing) *) .B mutable c_noflsh : .B bool ; (* Disable flush after INTR, QUIT, SUSP\&. *) .B mutable c_echo : .B bool ; (* Echo input characters\&. *) .B mutable c_echoe : .B bool ; (* Echo ERASE (to erase previous character)\&. *) .B mutable c_echok : .B bool ; (* Echo KILL (to erase the current line)\&. *) .B mutable c_echonl : .B bool ; (* Echo NL even if c_echo is not set\&. *) .B mutable c_vintr : .B char ; (* Interrupt character (usually ctrl\-C)\&. *) .B mutable c_vquit : .B char ; (* Quit character (usually ctrl\-\(rs)\&. *) .B mutable c_verase : .B char ; (* Erase character (usually DEL or ctrl\-H)\&. *) .B mutable c_vkill : .B char ; (* Kill line character (usually ctrl\-U)\&. *) .B mutable c_veof : .B char ; (* End\-of\-file character (usually ctrl\-D)\&. *) .B mutable c_veol : .B char ; (* Alternate end\-of\-line char\&. (usually none)\&. *) .B mutable c_vmin : .B int ; (* Minimum number of characters to read before the read request is satisfied\&. *) .B mutable c_vtime : .B int ; (* Maximum read wait (in 0\&.1s units)\&. *) .B mutable c_vstart : .B char ; (* Start character (usually ctrl\-Q)\&. *) .B mutable c_vstop : .B char ; (* Stop character (usually ctrl\-S)\&. *) } .sp .sp .I val tcgetattr : .B file_descr -> terminal_io .sp Return the status of the terminal referred to by the given file descriptor\&. .sp .B "Raises Invalid_argument" on Windows .sp .I type setattr_when = | TCSANOW | TCSADRAIN | TCSAFLUSH .sp .sp .I val tcsetattr : .B file_descr -> setattr_when -> terminal_io -> unit .sp Set the status of the terminal referred to by the given file descriptor\&. The second argument indicates when the status change takes place: immediately ( .ft B TCSANOW .ft R ), when all pending output has been transmitted ( .ft B TCSADRAIN .ft R ), or after flushing all input that has been received but not read ( .ft B TCSAFLUSH .ft R )\&. .ft B TCSADRAIN .ft R is recommended when changing the output parameters; .ft B TCSAFLUSH .ft R , when changing the input parameters\&. .sp .B "Raises Invalid_argument" on Windows .sp .I val tcsendbreak : .B file_descr -> int -> unit .sp 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)\&. .sp .B "Raises Invalid_argument" on Windows .sp .I val tcdrain : .B file_descr -> unit .sp Waits until all output written on the given file descriptor has been transmitted\&. .sp .B "Raises Invalid_argument" on Windows .sp .I type flush_queue = | TCIFLUSH | TCOFLUSH | TCIOFLUSH .sp .sp .I val tcflush : .B file_descr -> flush_queue -> unit .sp Discard data written on the given file descriptor but not yet transmitted, or data received but not yet read, depending on the second argument: .ft B TCIFLUSH .ft R flushes data received but not read, .ft B TCOFLUSH .ft R flushes data written but not transmitted, and .ft B TCIOFLUSH .ft R flushes both\&. .sp .B "Raises Invalid_argument" on Windows .sp .I type flow_action = | TCOOFF | TCOON | TCIOFF | TCION .sp .sp .I val tcflow : .B file_descr -> flow_action -> unit .sp Suspend or restart reception or transmission of data on the given file descriptor, depending on the second argument: .ft B TCOOFF .ft R suspends output, .ft B TCOON .ft R restarts output, .ft B TCIOFF .ft R transmits a STOP character to suspend input, and .ft B TCION .ft R transmits a START character to restart input\&. .sp .B "Raises Invalid_argument" on Windows .sp .I val setsid : .B unit -> int .sp Put the calling process in a new session and detach it from its controlling terminal\&. .sp .B "Raises Invalid_argument" on Windows .sp