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Module Unix

module Unix: sig .. end
File descriptor.
module File_descr: sig .. end
File descriptor.

Error report

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, mostly BSD. All other errors are mapped to EUNKNOWNERR.
module Error: sig .. end
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.
val unix_error : int -> string -> string -> 'a
Raises Unix_error with a given errno, function name and argument
val error_message : error -> string
Return a string describing the given error code.
val handle_unix_error : (unit -> 'a) -> 'a
handle_unix_error f runs f () and returns the result. If the exception Unix_error is raised, it prints a message describing the error and exits with code 2.
val retry_until_no_eintr : (unit -> 'a) -> 'a
retry_until_no_eintr f returns f () unless f () fails with EINTR; in which case f () is run again until it raises a different error or returns a value.

Access to the process environment

If you're looking for getenv, that's in the Sys module.

val environment : unit -> string array
Return the process environment, as an array of strings with the format ``variable=value''.
val putenv : key:string -> data:string -> unit
Unix.putenv ~key ~data sets the value associated to a variable in the process environment. key is the name of the environment variable, and data its new associated value.
val unsetenv : string -> unit
unsetenv name deletes the variable name from the environment.

EINVAL name contained an ’=’ or an '\000' character.


Process handling

module Exit: sig .. end
The termination status of a process. 
module Exit_or_signal: sig .. end
module Exit_or_signal_or_stop: sig .. end
val exec : prog:string ->
       args:string list ->
       ?use_path:bool -> ?env:string list -> unit -> Core_kernel.Std.never_returns
exec ~prog ~args ?search_path ?env execs prog with args. If use_path = true (the default) and prog doesn't contain a slash, then exec searches the PATH environment variable for prog. If env is supplied, it is used as the environment when prog is executed.

The first element in args should be the program itself; the correct way to call exec is:

exec ~prog ~args: prog; arg1; arg2; ... ()

val fork_exec : prog:string ->
       args:string list ->
       ?use_path:bool -> ?env:string list -> unit -> Core_kernel.Std.Pid.t
fork_exec ~prog ~args ?use_path ?env () forks and execs prog with args in the child process, returning the child pid to the parent.
val fork : unit -> [ `In_the_child | `In_the_parent of Core_kernel.Std.Pid.t ]
fork () forks a new process. The return value indicates whether we are continuing in the child or the parent, and if the parent, includes the child's process id.

wait{,_nohang,_untraced,_nohang_untraced} ?restart wait_on is a family of functions that wait on a process to exit (normally or via a signal) or be stopped by a signal (if untraced is used). The wait_on argument specifies which processes to wait on. The nohang variants return None immediately if no such process exists. If nohang is not used, waitpid will block until one of the desired processes exits.

The non-nohang variants have a restart flag with (default true) that causes the system call to be retried upon EAGAIN|EINTR. The nohang variants do not have this flag because they don't block.

type wait_on = [ `Any
       | `Group of Core_kernel.Std.Pid.t
       | `My_group
       | `Pid of Core_kernel.Std.Pid.t ] 
val wait : ?restart:bool ->
       wait_on -> Core_kernel.Std.Pid.t * Exit_or_signal.t
val wait_nohang : wait_on ->
       (Core_kernel.Std.Pid.t * Exit_or_signal.t) option
val wait_untraced : ?restart:bool ->
       wait_on ->
       Core_kernel.Std.Pid.t * Exit_or_signal_or_stop.t
val wait_nohang_untraced : wait_on ->
       (Core_kernel.Std.Pid.t * Exit_or_signal_or_stop.t) option
val waitpid : Core_kernel.Std.Pid.t -> Exit_or_signal.t
waitpid pid waits for child process pid to terminate, and returns its exit status. waitpid_exn is like waitpid, except it only returns if the child exits with status zero, and raises if the child terminates in any other way.
val waitpid_exn : Core_kernel.Std.Pid.t -> unit
val system : string -> Exit_or_signal.t
Execute the given command, wait until it terminates, and return its termination status. The string is interpreted by the shell /bin/sh and therefore can contain redirections, quotes, variables, etc. The result WEXITED 127 indicates that the shell couldn't be executed.
val getpid : unit -> Core_kernel.Std.Pid.t
Return the pid of the process.
val getppid : unit -> Core_kernel.Std.Pid.t option
Return the pid of the parent process.
val getppid_exn : unit -> Core_kernel.Std.Pid.t
Return the pid of the parent process, if you're really sure you're never going to be the init process.
val nice : int -> int
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.

Basic file input/output


The abstract type of file descriptors.
val stdin : File_descr.t
File descriptor for standard input.
val stdout : File_descr.t
File descriptor for standard output.
val stderr : File_descr.t
File descriptor for standard standard error.

The flags to UnixLabels.openfile.
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 Unix.openfile*)
Open for reading
type file_perm = int 
val openfile : ?perm:file_perm ->
       mode:open_flag list -> string -> File_descr.t
Open the named file with the given flags. Third argument is the permissions to give to the file if it is created. Return a file descriptor on the named file. Default permissions 0o644.
module Open_flags: sig .. end
val fcntl_getfl : File_descr.t -> Open_flags.t
fcntl_getfl fd gets the current flags for fd from the open-file-descriptor table via the system call fcntl(fd, F_GETFL). See "man fcntl".
val fcntl_setfl : File_descr.t -> Open_flags.t -> unit
fcntl_setfl fd flags sets the flags for fd in the open-file-descriptor table via the system call fcntl(fd, F_SETFL, flags). See "man fcntl". As per the Linux man page, on Linux this only allows append and nonblock to be set.
val close : ?restart:bool -> File_descr.t -> unit
Close a file descriptor.
val with_file : ?perm:file_perm ->
       string ->
       mode:open_flag list -> f:(File_descr.t -> 'a) -> 'a
with_file file ~mode ~perm ~f opens file, and applies f to the resulting file descriptor. When f finishes (or raises), with_file closes the descriptor and returns the result of f (or raises).
val read : ?restart:bool ->
       ?pos:int -> ?len:int -> File_descr.t -> buf:string -> int
read fd buff ofs len reads len characters from descriptor fd, storing them in string buff, starting at position ofs in string buff. Return the number of characters actually read.
val write : ?pos:int -> ?len:int -> File_descr.t -> buf:string -> int
write fd buff ofs len writes len characters to descriptor fd, taking them from string buff, starting at position ofs in string buff. Return the number of characters actually written.

When an error is reported some characters might have already been written. Use single_write instead to ensure that this is not the case.

WARNING: write is an interruptible call and has no way to handle EINTR properly. You should most probably be using single write.

val single_write : ?restart:bool ->
       ?pos:int -> ?len:int -> File_descr.t -> buf:string -> int
Same as write but ensures that all errors are reported and that no character has ever been written when an error is reported.

Interfacing with the standard input/output library

val in_channel_of_descr : File_descr.t -> Core_kernel.Std.In_channel.t
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.
val out_channel_of_descr : File_descr.t -> Core_kernel.Std.Out_channel.t
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.
val descr_of_in_channel : Core_kernel.Std.In_channel.t -> File_descr.t
Return the descriptor corresponding to an input channel.
val descr_of_out_channel : Core_kernel.Std.Out_channel.t -> File_descr.t
Return the descriptor corresponding to an output channel.

Seeking and truncating

type seek_command = Unix.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*)
POSITIONING modes for UnixLabels.lseek.
val lseek : File_descr.t -> int64 -> mode:seek_command -> int64
val truncate : string -> len:int64 -> unit
Truncates the named file to the given size.
val ftruncate : File_descr.t -> len:int64 -> unit
Truncates the file corresponding to the given descriptor to the given size.

File statistics

type file_kind = Unix.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*) 
type stats = Unix.LargeFile.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 minor number*)
   st_size : int64; (*Size in bytes*)
   st_atime : float; (*Last access time*)
   st_mtime : float; (*Last modification time*)
   st_ctime : float; (*Last status change time*)
} 
val stat : string -> stats
Return the information for the named file.
val lstat : string -> stats
Same as UnixLabels.stat, but in case the file is a symbolic link, return the information for the link itself.
val fstat : File_descr.t -> stats
Return the information for the file associated with the given descriptor.
module Native_file: sig .. end

Locking

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 Unix.lockf.
val lockf : File_descr.t ->
       mode:lock_command -> len:Core_kernel.Std.Int64.t -> unit
module Flock_command: sig .. end
val flock : File_descr.t -> Flock_command.t -> bool
flock fd cmd places or releases a lock on the fd as per the flock C call of the same name.
val isatty : File_descr.t -> bool
Return true if the given file descriptor refers to a terminal or console window, false otherwise.

Operations on file names

val unlink : string -> unit
Removes the named file
val remove : string -> unit
Removes the named file or directory
val rename : src:string -> dst:string -> unit
rename old new changes the name of a file from old to new.
val link : ?force:bool -> target:string -> link_name:string -> unit -> unit
link ?force ~target ~link_name () creates a hard link named link_name to the file named target. If force is true, an existing entry in place of link_name will be unlinked. This unlinking may raise a Unix error, e.g. if the entry is a directory.

File permissions and ownership

val chmod : string -> perm:file_perm -> unit
Change the permissions of the named file.
val fchmod : File_descr.t -> perm:file_perm -> unit
Change the permissions of an opened file.
val chown : string -> uid:int -> gid:int -> unit
Change the owner uid and owner gid of the named file.
val fchown : File_descr.t -> uid:int -> gid:int -> unit
Change the owner uid and owner gid of an opened file.
val umask : int -> int
Set the process creation mask, and return the previous mask.
val access : string ->
       [ `Exec | `Exists | `Read | `Write ] list ->
       (unit, exn) Core_kernel.Std.Result.t
Check that the process has the given permissions over the named file.
val access_exn : string -> [ `Exec | `Exists | `Read | `Write ] list -> unit

Operations on file descriptors

val dup : File_descr.t -> File_descr.t
Return a new file descriptor referencing the same file as the given descriptor.
val dup2 : src:File_descr.t -> dst:File_descr.t -> unit
dup2 fd1 fd2 duplicates fd1 to fd2, closing fd2 if already opened.
val set_nonblock : File_descr.t -> 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.t -> unit
Clear the ``non-blocking'' flag on the given descriptor. See UnixLabels.set_nonblock.
val set_close_on_exec : File_descr.t -> 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 functions.
val clear_close_on_exec : File_descr.t -> unit
Clear the ``close-on-exec'' flag on the given descriptor. See UnixLabels.set_close_on_exec.

Directories

val mkdir : ?perm:file_perm -> string -> unit
Create a directory. The permissions of the created directory are (perm & ~umask & 0777). The default perm is 0777.
val mkdir_p : ?perm:file_perm -> string -> unit
Create a directory recursively. The permissions of the created directory are those granted by mkdir ~perm.
val rmdir : string -> unit
Remove an empty directory.
val chdir : string -> unit
Change the process working directory.
val getcwd : unit -> string
Return the name of the current working directory.
val chroot : string -> unit
Change the process root directory.
type dir_handle = Unix.dir_handle
The type of descriptors over opened directories.
val opendir : ?restart:bool -> string -> dir_handle
Open a descriptor on a directory
val readdir : dir_handle -> string
Return the next entry in a directory.
Raises End_of_file when the end of the directory has been reached.
val rewinddir : dir_handle -> unit
Reposition the descriptor to the beginning of the directory
val closedir : dir_handle -> unit
Close a directory descriptor.

Pipes and redirections

val pipe : unit -> File_descr.t * File_descr.t
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.
val mkfifo : string -> perm:file_perm -> unit
Create a named pipe with the given permissions.

High-level process and redirection management

module Process_info: sig .. end

Low-level process
val create_process : prog:string -> args:string list -> Process_info.t
create_process ~prog ~args forks a new process that executes the program prog with arguments args. The function returns the pid of the process along with file descriptors attached to stdin, stdout, and stderr of the new process. The executable file prog is searched for in the path. The new process has the same environment as the current process. Unlike in execve the program name is automatically passed as the first argument.
type env = [ `Extend of (string * string) list | `Replace of (string * string) list ]
create_process_env ~prog ~args ~env as create process, but takes an additional parameter that extends, or replaces the current environment. No effort is made to ensure that the keys passed in as env are unique, so if an environment variable is set twice the second version will override the first.
val create_process_env : ?working_dir:string ->
       prog:string ->
       args:string list -> env:env -> unit -> Process_info.t
val open_process_in : string -> Pervasives.in_channel
High-level pipe and process management. These functions (with UnixLabels.open_process_out and UnixLabels.open_process) run the given command in parallel with the program, and return channels connected to the standard input and/or the standard output of the command. The command is interpreted by the shell /bin/sh (cf. system). Warning: writes on channels are buffered, hence be careful to call Pervasives.flush at the right times to ensure correct synchronization.
val open_process_out : string -> Pervasives.out_channel
See UnixLabels.open_process_in.
val open_process : string -> Pervasives.in_channel * Pervasives.out_channel
See UnixLabels.open_process_in.
module Process_channels: sig .. end
Similar to UnixLabels.open_process, but the second argument specifies the environment passed to the command. 
val open_process_full : string -> env:string array -> Process_channels.t
val close_process_in : Pervasives.in_channel -> Exit_or_signal.t
Close channels opened by UnixLabels.open_process_in, wait for the associated command to terminate, and return its termination status.
val close_process_out : Pervasives.out_channel -> Exit_or_signal.t
Close channels opened by UnixLabels.open_process_out, wait for the associated command to terminate, and return its termination status.
val close_process : Pervasives.in_channel * Pervasives.out_channel -> Exit_or_signal.t
Close channels opened by UnixLabels.open_process, wait for the associated command to terminate, and return its termination status.
val close_process_full : Process_channels.t -> Exit_or_signal.t
Close channels opened by UnixLabels.open_process_full, wait for the associated command to terminate, and return its termination status.


val symlink : src:string -> dst:string -> unit
symlink source dest creates the file dest as a symbolic link to the file source.
val readlink : string -> string
Read the contents of a link.

Polling

module Select_fds: sig .. end
Wait until some input/output operations become possible on some channels. 
type select_timeout = [ `After of float | `Immediately | `Never ] 
val select : ?restart:bool ->
       read:File_descr.t list ->
       write:File_descr.t list ->
       except:File_descr.t list ->
       timeout:select_timeout -> unit -> Select_fds.t
Setting restart to true means that we want select to restart automatically on EINTR (instead of propagating the exception)...
val pause : unit -> unit
Wait until a non-ignored, non-blocked signal is delivered.

Time functions

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..59*)
   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.
val time : unit -> float
Return the current time since 00:00:00 GMT, Jan. 1, 1970, in seconds.
val gettimeofday : unit -> float
Same as Unix.time above, but with resolution better than 1 second.
val gmtime : float -> tm
Convert a time in seconds, as returned by UnixLabels.time, into a date and a time. Assumes UTC.
val timegm : tm -> float
Convert a UTC time in a tm record to a time in seconds
val localtime : float -> tm
Convert a time in seconds, as returned by UnixLabels.time, into a date and a time. Assumes the local time zone.
val mktime : tm -> float * tm
Convert a date and time, specified by the tm argument, into a time in seconds, as returned by UnixLabels.time. 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. The tm argument is interpreted in the local time zone.
val strftime : tm -> string -> string
Convert a date and time, specified by the tm argument, into a formatted string. See 'man strftime' for format options.
val strptime : fmt:string -> string -> Unix.tm
Given a format string, convert a corresponding string to a date and time See 'man strptime' for format options.
val alarm : int -> int
Schedule a SIGALRM signal after the given number of seconds.
val sleep : int -> unit
Stop execution for the given number of seconds.
val nanosleep : float -> float
nanosleep f delays execution of the program for at least f seconds. The function can return earlier if a signal has been delivered, in which case the number of seconds left is returned. Any other failure raises an exception.
val times : unit -> process_times
Return the execution times of the process.
val utimes : string -> access:float -> modif:float -> unit
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.
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.
type interval_timer_status = Unix.interval_timer_status = {
   it_interval : float; (*Period*)
   it_value : float; (*Current value of the 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 disable the timer. Setting s.it_interval to zero causes the timer to be disabled after its next expiration.

User id, group id
It's highly recommended to read the straight unix docs on these functions for more color. You can get that info from man pages or http://www.opengroup.org/onlinepubs/000095399/functions/setuid.html
val getuid : unit -> int
Return the user id of the user executing the process.
val geteuid : unit -> int
Return the effective user id under which the process runs.
val setuid : int -> unit
Sets the real user id and effective user id for the process. Only use this when superuser. To setuid as an ordinary user, see Core_extended.Unix.seteuid.
val getgid : unit -> int
Return the group id of the user executing the process.
val getegid : unit -> int
Return the effective group id under which the process runs.
val setgid : int -> unit
Set the real group id and effective group id for the process.
module Passwd: sig .. end
Structure of entries in the passwd database 
module Group: sig .. end
Structure of entries in the groups database. 
val getlogin : unit -> string
Return the login name of the user executing the process.
module Protocol_family: sig .. end

Internet addresses

module Inet_addr: sig .. end
module Cidr: sig .. end
A representation of CIDR netmasks (e.g.

Sockets

type socket_domain = Unix.socket_domain =
| PF_UNIX (*Unix domain*)
| PF_INET (*Internet domain*)
| PF_INET6
The type of socket domains.
type socket_type = Unix.socket_type =
| SOCK_STREAM (*Stream socket*)
| SOCK_DGRAM (*Datagram socket*)
| SOCK_RAW (*Raw socket*)
| SOCK_SEQPACKET
The type of socket kinds, specifying the semantics of communications.
type sockaddr = Unix.sockaddr =
| ADDR_UNIX of string
| ADDR_INET of Inet_addr.t * int
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 domain_of_sockaddr : sockaddr -> socket_domain
Return the socket domain adequate for the given socket address.
val socket : domain:socket_domain ->
       kind:socket_type -> protocol:int -> File_descr.t
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.
val socketpair : domain:socket_domain ->
       kind:socket_type ->
       protocol:int -> File_descr.t * File_descr.t
Create a pair of unnamed sockets, connected together.
val accept : File_descr.t -> File_descr.t * 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.
val bind : File_descr.t -> addr:sockaddr -> unit
Bind a socket to an address.
val connect : File_descr.t -> addr:sockaddr -> unit
Connect a socket to an address.
val listen : File_descr.t -> 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 =
| SHUTDOWN_RECEIVE (*Close for receiving*)
| SHUTDOWN_SEND (*Close for sending*)
| SHUTDOWN_ALL (*Close both*)
The type of commands for shutdown.
val shutdown : File_descr.t -> mode:shutdown_command -> unit
val getsockname : File_descr.t -> sockaddr
Return the address of the given socket.
val getpeername : File_descr.t -> sockaddr
Return the address of the host connected to the given socket.
type msg_flag = Unix.msg_flag =
| MSG_OOB
| MSG_DONTROUTE
| MSG_PEEK
The flags for UnixLabels.recv, UnixLabels.recvfrom, UnixLabels.send and UnixLabels.sendto.
val recv : File_descr.t ->
       buf:string -> pos:int -> len:int -> mode:msg_flag list -> int
Receive data from an unconnected socket.
val recvfrom : File_descr.t ->
       buf:string ->
       pos:int ->
       len:int -> mode:msg_flag list -> int * sockaddr
Receive data from an unconnected socket.
val send : File_descr.t ->
       buf:string -> pos:int -> len:int -> mode:msg_flag list -> int
Send data over an unconnected socket.
val sendto : File_descr.t ->
       buf:string ->
       pos:int ->
       len:int -> mode:msg_flag list -> addr:sockaddr -> int
Send data over an unconnected socket.

Socket options

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
| TCP_NODELAY (*Control the Nagle algorithm for TCP sockets*)
| IPV6_ONLY (*Forbid binding an IPv6 socket to an IPv4 address*)
The socket options that can be consulted with UnixLabels.getsockopt and modified with UnixLabels.setsockopt. These options have a boolean (true/false) value.
type socket_int_option =
| SO_SNDBUF (*Size of send buffer*)
| SO_RCVBUF (*Size of received buffer*)
| SO_ERROR (*Report the error status and clear it*)
| SO_TYPE (*Report the socket type*)
| SO_RCVLOWAT (*Minimum number of bytes to process for input operations*)
| SO_SNDLOWAT 
type socket_optint_option =
| SO_LINGER (*Whether to linger on closed connections with sexp that have data present, and for how long (in seconds)*)
The socket options that can be consulted with UnixLabels.getsockopt_optint and modified with UnixLabels.setsockopt_optint. These options have a value of type int option, with None meaning ``disabled''.
type socket_float_option =
| SO_RCVTIMEO (*Timeout for input operations*)
| SO_SNDTIMEO (*Timeout for output operations*)
The socket options that can be consulted with UnixLabels.getsockopt_float and modified with UnixLabels.setsockopt_float. These options have a floating-point value representing a time in seconds. The value 0 means infinite timeout.
val getsockopt : File_descr.t -> socket_bool_option -> bool
val setsockopt : File_descr.t -> socket_bool_option -> bool -> unit
Set or clear a boolean-valued option in the given socket.
val getsockopt_int : File_descr.t -> socket_int_option -> int
Same as UnixLabels.getsockopt for an integer-valued socket option.
val setsockopt_int : File_descr.t -> socket_int_option -> int -> unit
Same as UnixLabels.setsockopt for an integer-valued socket option.
val getsockopt_optint : File_descr.t -> socket_optint_option -> int option
Same as UnixLabels.getsockopt for a socket option whose value is an int option.
val setsockopt_optint : File_descr.t ->
       socket_optint_option -> int option -> unit
Same as UnixLabels.setsockopt for a socket option whose value is an int option.
val getsockopt_float : File_descr.t -> socket_float_option -> float
Same as UnixLabels.getsockopt for a socket option whose value is a floating-point number.
val setsockopt_float : File_descr.t -> socket_float_option -> float -> unit
Same as UnixLabels.setsockopt for a socket option whose value is a floating-point number.

High-level network connection functions

val open_connection : sockaddr -> Pervasives.in_channel * Pervasives.out_channel
Connect to a server at the given address. Return a pair of buffered channels connected to the server. Remember to call Pervasives.flush on the output channel at the right times to ensure correct synchronization.
val shutdown_connection : Pervasives.in_channel -> unit
``Shut down'' a connection established with UnixLabels.open_connection; that is, transmit an end-of-file condition to the server reading on the other side of the connection.
val establish_server : (Pervasives.in_channel -> Pervasives.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 UnixLabels.establish_server never returns normally.

Host and protocol databases

val gethostname : unit -> string
Return the name of the local host.
module Host: sig .. end
module Protocol: sig .. end
module Service: sig .. end
type 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;
}
Address information returned by Unix.getaddrinfo.
type 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 Unix.getaddrinfo.
val getaddrinfo : string ->
       string -> getaddrinfo_option list -> addr_info list
getaddrinfo host service opts returns a list of Unix.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 = {
   ni_hostname : string; (*Name or IP address of host*)
   ni_service : string;
}
Host and service information returned by Unix.getnameinfo.

Name of service or port number

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 
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. Raise Not_found if an error occurs.

Getting terminal size



Terminal interface


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.
module Terminal_io: sig .. end
val get_sockaddr : string -> int -> sockaddr
Get a sockaddr from a hostname or IP, and a port
val set_in_channel_timeout : Pervasives.in_channel -> float -> unit
Set a timeout for a socket associated with an in_channel
val set_out_channel_timeout : Pervasives.out_channel -> float -> unit
Set a timeout for a socket associated with an out_channel
val exit_immediately : int -> 'a
exit_immediately exit_code immediately calls the exit system call with the given exit code without performing any other actions (unlike Pervasives.exit). Does not return.

Filesystem functions


val mknod : ?file_kind:file_kind ->
       ?perm:int -> ?major:int -> ?minor:int -> string -> unit
mknod ?file_kind ?perm ?major ?minor path creates a filesystem entry. Note that only FIFO-entries are guaranteed to be supported across all platforms as required by the POSIX-standard. On Linux directories and symbolic links cannot be created with this function. Use Unix.mkdir and Unix.symlink instead there respectively.
Raises
file_kind : default = S_REG (= regular file)
perm : default = 0o600 (= read/write for user only)
major : default = 0
minor : default = 0

I/O vectors


module IOVec: sig .. end
I/O-vectors for scatter/gather-operations

I/O functions


val dirfd : dir_handle -> File_descr.t

Extract a file descriptor from a directory handle.
val sync : unit -> unit
Synchronize all filesystem buffers with disk.
val fsync : File_descr.t -> unit
val fdatasync : File_descr.t -> unit
Synchronize the kernel buffers of a given file descriptor with disk, but do not necessarily write file attributes.
val readdir_ino : dir_handle -> string * nativeint
readdir_ino dh return the next entry in a directory (((filename, inode)).
Raises End_of_file when the end of the directory has been reached.
val read_assume_fd_is_nonblocking : File_descr.t -> ?pos:int -> ?len:int -> string -> int
read_assume_fd_is_nonblocking fd ?pos ?len buf calls the system call read ASSUMING THAT IT IS NOT GOING TO BLOCK. Reads at most len bytes into buffer buf starting at position pos.
Raises Returns the number of bytes actually read.
pos : = 0
len : = String.length buf - pos
val write_assume_fd_is_nonblocking : File_descr.t -> ?pos:int -> ?len:int -> string -> int
write_assume_fd_is_nonblocking fd ?pos ?len buf calls the system call write ASSUMING THAT IT IS NOT GOING TO BLOCK. Writes at most len bytes from buffer buf starting at position pos.
Raises Returns the number of bytes actually written.
pos : = 0
len : = String.length buf - pos
val writev_assume_fd_is_nonblocking : File_descr.t -> ?count:int -> string IOVec.t array -> int
writev_assume_fd_is_nonblocking fd ?count iovecs calls the system call writev ASSUMING THAT IT IS NOT GOING TO BLOCK using count I/O-vectors iovecs.
Raises Returns the number of bytes actually written.
val writev : File_descr.t -> ?count:int -> string IOVec.t array -> int
writev fd ?count iovecs like Unix.writev_assume_fd_is_nonblocking, but does not require the descriptor to not block. If you feel you have to use this function, you should probably have chosen I/O-vectors that build on bigstrings, because this function has to internally blit the I/O-vectors (ordinary OCaml strings) to intermediate buffers on the C-heap.
Raises Returns the number of bytes actually written.
val pselect : File_descr.t list ->
       File_descr.t list ->
       File_descr.t list ->
       float ->
       int list ->
       File_descr.t list * File_descr.t list *
       File_descr.t list
pselect rfds wfds efds timeout sigmask like Unix.select but also allows one to wait for the arrival of signals.
module RLimit: sig .. end
Resource limits 
module Resource_usage: sig .. end
Resource usage -- For details, "man getrusage" 
type sysconf =
| ARG_MAX
| CHILD_MAX
| HOST_NAME_MAX
| LOGIN_NAME_MAX
| OPEN_MAX
| PAGESIZE
| RE_DUP_MAX
| STREAM_MAX
| SYMLOOP_MAX
| TTY_NAME_MAX
| TZNAME_MAX
| POSIX_VERSION
| PHYS_PAGES
| AVPHYS_PAGES
| IOV_MAX

System configuration


val sysconf : sysconf -> int64

Temporary file and directory creation


val mkstemp : string -> string * File_descr.t
mkstemp prefix creates and opens a unique temporary file with prefix, automatically appending a suffix of six random characters to make the name unique. Unlike C's mkstemp, prefix should not include six X's at the end.
Raises Unix_error on errors.
val mkdtemp : string -> string
mkdtemp prefix creates a temporary directory with prefix, automatically appending a suffix of six random characters to make the name unique.
Raises Unix_error on errors. k

Signal handling


val abort : unit -> 'a

User id, group id


val initgroups : string -> int -> unit
val getgrouplist : string -> int -> int array
getgrouplist user group returns the list of groups to which user belongs. See 'man getgrouplist'.
val getgroups : unit -> int array
Return the list of groups to which the user executing the process belongs.

Globbing and shell expansion


val fnmatch : ?flags:[ `Casefold
              | `File_name
              | `Leading_dir
              | `No_escape
              | `Pathname
              | `Period ] list ->
       pat:string -> string -> bool
val wordexp : (?flags:[ `No_cmd | `Show_err | `Undef ] list -> string -> string array)
       Core_kernel.Std.Or_error.t

System information


module Utsname: sig .. end
val uname : unit -> Utsname.t

Additional IP functionality


val if_indextoname : int -> string
val mcast_join : ?ifname:string -> File_descr.t -> sockaddr -> unit
mcast_join ?ifname sock addr join a multicast group at addr with socket sock, optionally using network interface ifname.
ifname : default = any interface
val mcast_leave : ?ifname:string -> File_descr.t -> sockaddr -> unit
mcast_leave ?ifname sock addr leaves a multicast group at addr with socket sock, optionally using network interface ifname.
ifname : default = any interface
val get_mcast_ttl : File_descr.t -> int
get_mcast_ttl sock reads the time-to-live value of outgoing multicast packets for socket sock.
val set_mcast_ttl : File_descr.t -> int -> unit
set_mcast_ttl sock ttl sets the time-to-live value of outgoing multicast packets for socket sock to ttl.
val get_mcast_loop : File_descr.t -> bool
get_mcast_loop sock reads the boolean argument that determines whether sent multicast packets are looped back to local sockets.
val set_mcast_loop : File_descr.t -> bool -> unit
set_mcast_loop sock loop sets the boolean argument that determines whether sent multicast packets are looped back to local sockets.
module Scheduler: sig .. end
module Priority: sig .. end
module Mman: sig .. end
val error_of_sexp : Sexplib.Sexp.t -> error
val sexp_of_error : error -> Sexplib.Sexp.t
Unknown error

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.

Return a string describing the given error code.

handle_unix_error f runs f () and returns the result. If the exception Unix_error is raised, it prints a message describing the error and exits with code 2.

retry_until_no_eintr f returns f () unless f () fails with EINTR; in which case f () is run again until it raises a different error or returns a value.

Access to the process environment

If you're looking for getenv, that's in the Sys module.

Return the process environment, as an array of strings with the format ``variable=value''.

Unix.putenv ~key ~data sets the value associated to a variable in the process environment. key is the name of the environment variable, and data its new associated value.

unsetenv name deletes the variable name from the environment.

EINVAL name contained an ’=’ or an '\000' character.

Process handling


The termination status of a process.

of_unix assumes that any signal numbers in the incoming value are O'Caml internal signal numbers.

of_unix assumes that any signal numbers in the incoming value are O'Caml internal signal numbers.

exec ~prog ~args ?search_path ?env execs prog with args. If use_path = true (the default) and prog doesn't contain a slash, then exec searches the PATH environment variable for prog. If env is supplied, it is used as the environment when prog is executed.

The first element in args should be the program itself; the correct way to call exec is:

exec ~prog ~args: prog; arg1; arg2; ... ()

fork_exec ~prog ~args ?use_path ?env () forks and execs prog with args in the child process, returning the child pid to the parent.

fork () forks a new process. The return value indicates whether we are continuing in the child or the parent, and if the parent, includes the child's process id.

wait{,_nohang,_untraced,_nohang_untraced} ?restart wait_on is a family of functions that wait on a process to exit (normally or via a signal) or be stopped by a signal (if untraced is used). The wait_on argument specifies which processes to wait on. The nohang variants return None immediately if no such process exists. If nohang is not used, waitpid will block until one of the desired processes exits.

The non-nohang variants have a restart flag with (default true) that causes the system call to be retried upon EAGAIN|EINTR. The nohang variants do not have this flag because they don't block.

val wait_on_of_sexp : Sexplib.Sexp.t -> wait_on
val __wait_on_of_sexp__ : Sexplib.Sexp.t -> wait_on
val sexp_of_wait_on : wait_on -> Sexplib.Sexp.t

waitpid pid waits for child process pid to terminate, and returns its exit status. waitpid_exn is like waitpid, except it only returns if the child exits with status zero, and raises if the child terminates in any other way.

Execute the given command, wait until it terminates, and return its termination status. The string is interpreted by the shell /bin/sh and therefore can contain redirections, quotes, variables, etc. The result WEXITED 127 indicates that the shell couldn't be executed.

Return the pid of the process.

Return the pid of the parent process.

Return the pid of the parent process, if you're really sure you're never going to be the init process.

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.

Basic file input/output


The abstract type of file descriptors.

File descriptor for standard input.

File descriptor for standard output.

File descriptor for standard standard error.

The flags to UnixLabels.openfile.
val open_flag_of_sexp : Sexplib.Sexp.t -> open_flag
val sexp_of_open_flag : open_flag -> Sexplib.Sexp.t
Set the close-on-exec flag on the descriptor returned by Unix.openfile
val open_flag_of_sexp : Sexplib.Sexp.t -> open_flag
val sexp_of_open_flag : open_flag -> Sexplib.Sexp.t
Windows only: allow the file to be deleted while still open
val file_perm_of_sexp : Sexplib.Sexp.t -> file_perm
The type of file access rights.
val sexp_of_file_perm : file_perm -> Sexplib.Sexp.t

Open the named file with the given flags. Third argument is the permissions to give to the file if it is created. Return a file descriptor on the named file. Default permissions 0o644.

Open_flags.t represents the flags associated with a file descriptor in the open-file-descriptor table. It deals with the same thing as OCaml's open_flag type; however, it uses Core's Flags approach and the underlying integer bitmask representation, and so interoperates more smoothly with C.

access mode.

These three flags are not individual bits like flags usually are. The access mode is represented by the lower two bits of the Open_flags.t. A particular Open_flags.t should include exactly one access mode. Combining different Open_flags.t's using flags operations (e.g +) is only sensible if they have the same access mode.

creation

can_read t iff t has rdonly or rdwr

can_read t iff t has wronly or rdwr

fcntl_getfl fd gets the current flags for fd from the open-file-descriptor table via the system call fcntl(fd, F_GETFL). See "man fcntl".

fcntl_setfl fd flags sets the flags for fd in the open-file-descriptor table via the system call fcntl(fd, F_SETFL, flags). See "man fcntl". As per the Linux man page, on Linux this only allows append and nonblock to be set.

Close a file descriptor.

with_file file ~mode ~perm ~f opens file, and applies f to the resulting file descriptor. When f finishes (or raises), with_file closes the descriptor and returns the result of f (or raises).

read fd buff ofs len reads len characters from descriptor fd, storing them in string buff, starting at position ofs in string buff. Return the number of characters actually read.

write fd buff ofs len writes len characters to descriptor fd, taking them from string buff, starting at position ofs in string buff. Return the number of characters actually written.

When an error is reported some characters might have already been written. Use single_write instead to ensure that this is not the case.

WARNING: write is an interruptible call and has no way to handle EINTR properly. You should most probably be using single write.

Same as write but ensures that all errors are reported and that no character has ever been written when an error is reported.

Interfacing with the standard input/output library


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.

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.

Return the descriptor corresponding to an input channel.

Return the descriptor corresponding to an output channel.

Seeking and truncating

val seek_command_of_sexp : Sexplib.Sexp.t -> seek_command
POSITIONING modes for UnixLabels.lseek.
val sexp_of_seek_command : seek_command -> Sexplib.Sexp.t
indicates positions relative to the end of the file

Set the current position for a file descriptor

Truncates the named file to the given size.

Truncates the file corresponding to the given descriptor to the given size.

File statistics

val file_kind_of_sexp : Sexplib.Sexp.t -> file_kind
val sexp_of_file_kind : file_kind -> Sexplib.Sexp.t
Socket
val stats_of_sexp : Sexplib.Sexp.t -> stats
The informations returned by the UnixLabels.stat calls.
val sexp_of_stats : stats -> Sexplib.Sexp.t

Return the information for the named file.

Same as UnixLabels.stat, but in case the file is a symbolic link, return the information for the link itself.

Return the information for the file associated with the given descriptor.

The informations returned by the UnixLabels.stat calls.

Device number

Inode number

Kind of the file

Access rights

Number of links

User id of the owner

Group ID of the file's group

Device minor number

Size in bytes

Last access time

Last modification time

Last status change time

Return the information for the named file.

Same as UnixLabels.stat, but in case the file is a symbolic link, return the information for the link itself.

Return the information for the file associated with the given descriptor.

Locking

val lock_command_of_sexp : Sexplib.Sexp.t -> lock_command
Commands for Unix.lockf.
val sexp_of_lock_command : lock_command -> Sexplib.Sexp.t
Lock a region for reading, or fail if already locked

lockf fd cmd size place a lock on a file_descr that prevents any other process from * calling lockf successfully on the same file. Due to a limitation in the current * implementation the length will be converted to a native int, potentially throwing an * exception if it is too large.

flock fd cmd places or releases a lock on the fd as per the flock C call of the same name.

Return true if the given file descriptor refers to a terminal or console window, false otherwise.

Operations on file names


Removes the named file

Removes the named file or directory

rename old new changes the name of a file from old to new.

link ?force ~target ~link_name () creates a hard link named link_name to the file named target. If force is true, an existing entry in place of link_name will be unlinked. This unlinking may raise a Unix error, e.g. if the entry is a directory.

File permissions and ownership


Change the permissions of the named file.

Change the permissions of an opened file.

Change the owner uid and owner gid of the named file.

Change the owner uid and owner gid of an opened file.

Set the process creation mask, and return the previous mask.

Check that the process has the given permissions over the named file.

Operations on file descriptors


Return a new file descriptor referencing the same file as the given descriptor.

dup2 fd1 fd2 duplicates fd1 to fd2, closing fd2 if already opened.

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.

Clear the ``non-blocking'' flag on the given descriptor. See UnixLabels.set_nonblock.

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 functions.

Clear the ``close-on-exec'' flag on the given descriptor. See UnixLabels.set_close_on_exec.

Directories


Create a directory. The permissions of the created directory are (perm & ~umask & 0777). The default perm is 0777.

Create a directory recursively. The permissions of the created directory are those granted by mkdir ~perm.

Remove an empty directory.

Change the process working directory.

Return the name of the current working directory.

Change the process root directory.

The type of descriptors over opened directories.

Open a descriptor on a directory

Return the next entry in a directory.

Reposition the descriptor to the beginning of the directory

Close a directory descriptor.

Pipes and redirections


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.

Create a named pipe with the given permissions.

High-level process and redirection management


Low-level process

create_process ~prog ~args forks a new process that executes the program prog with arguments args. The function returns the pid of the process along with file descriptors attached to stdin, stdout, and stderr of the new process. The executable file prog is searched for in the path. The new process has the same environment as the current process. Unlike in execve the program name is automatically passed as the first argument.
val env_of_sexp : Sexplib.Sexp.t -> env
create_process_env ~prog ~args ~env as create process, but takes an additional parameter that extends, or replaces the current environment. No effort is made to ensure that the keys passed in as env are unique, so if an environment variable is set twice the second version will override the first.
val __env_of_sexp__ : Sexplib.Sexp.t -> env
val sexp_of_env : env -> Sexplib.Sexp.t

High-level pipe and process management. These functions (with UnixLabels.open_process_out and UnixLabels.open_process) run the given command in parallel with the program, and return channels connected to the standard input and/or the standard output of the command. The command is interpreted by the shell /bin/sh (cf. system). Warning: writes on channels are buffered, hence be careful to call Pervasives.flush at the right times to ensure correct synchronization.

See UnixLabels.open_process_in.

See UnixLabels.open_process_in.

Similar to UnixLabels.open_process, but the second argument specifies the environment passed to the command. The result is a triple of channels connected to the standard output, standard input, and standard error of the command.

Close channels opened by UnixLabels.open_process_in, wait for the associated command to terminate, and return its termination status.

Close channels opened by UnixLabels.open_process_out, wait for the associated command to terminate, and return its termination status.

Close channels opened by UnixLabels.open_process, wait for the associated command to terminate, and return its termination status.

Close channels opened by UnixLabels.open_process_full, wait for the associated command to terminate, and return its termination status.



symlink source dest creates the file dest as a symbolic link to the file source.

Read the contents of a link.

Polling


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).
val sexp_of_select_timeout : select_timeout -> Sexplib.Sexp.t

Setting restart to true means that we want select to restart automatically on EINTR (instead of propagating the exception)...

Wait until a non-ignored, non-blocked signal is delivered.

Time functions

val process_times_of_sexp : Sexplib.Sexp.t -> process_times
The execution times (CPU times) of a process.
val sexp_of_process_times : process_times -> Sexplib.Sexp.t
val tm_of_sexp : Sexplib.Sexp.t -> tm
The type representing wallclock time and calendar date.
val sexp_of_tm : tm -> Sexplib.Sexp.t

Return the current time since 00:00:00 GMT, Jan. 1, 1970, in seconds.

Same as Unix.time above, but with resolution better than 1 second.

Convert a time in seconds, as returned by UnixLabels.time, into a date and a time. Assumes UTC.

Convert a UTC time in a tm record to a time in seconds

Convert a time in seconds, as returned by UnixLabels.time, into a date and a time. Assumes the local time zone.

Convert a date and time, specified by the tm argument, into a time in seconds, as returned by UnixLabels.time. 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. The tm argument is interpreted in the local time zone.

Convert a date and time, specified by the tm argument, into a formatted string. See 'man strftime' for format options.

Given a format string, convert a corresponding string to a date and time See 'man strptime' for format options.

Schedule a SIGALRM signal after the given number of seconds.

Stop execution for the given number of seconds.

nanosleep f delays execution of the program for at least f seconds. The function can return earlier if a signal has been delivered, in which case the number of seconds left is returned. Any other failure raises an exception.

Return the execution times of the process.

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.
val interval_timer_of_sexp : Sexplib.Sexp.t -> interval_timer
The three kinds of interval timers.
val sexp_of_interval_timer : interval_timer -> Sexplib.Sexp.t
(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.
val interval_timer_status_of_sexp : Sexplib.Sexp.t -> interval_timer_status
The type describing the status of an interval timer
val sexp_of_interval_timer_status : interval_timer_status -> Sexplib.Sexp.t

Return the current status of the given interval timer.

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 disable the timer. Setting s.it_interval to zero causes the timer to be disabled after its next expiration.

User id, group id
It's highly recommended to read the straight unix docs on these functions for more color. You can get that info from man pages or http://www.opengroup.org/onlinepubs/000095399/functions/setuid.html

Return the user id of the user executing the process.

Return the effective user id under which the process runs.

Sets the real user id and effective user id for the process. Only use this when superuser. To setuid as an ordinary user, see Core_extended.Unix.seteuid.

Return the group id of the user executing the process.

Return the effective group id under which the process runs.

Set the real group id and effective group id for the process.

Structure of entries in the passwd database

getpwents is a thread-safe wrapper over the low-level passwd database functions.

Structure of entries in the groups database.

Return the login name of the user executing the process.

Internet addresses


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. Raise Failure when given a string that does not match these formats.

Call of_string and if that fails, use Host.getbyname.

Return the printable representation of the given Internet address. See of_string for a description of the printable representation.

A special address, for use only with bind, representing all the Internet addresses that the host machine possesses.

Special addresses representing the host machine.

Some things (like the kernel) report addresses as hex or decimal strings. Provide conversion functions.

inet4_addr_to_int32_exn t = 0l when t = Inet_addr.of_string ("0.0.0.0"). An exception is raised if t is a not an IPv4 address.

A representation of CIDR netmasks (e.g. "192.168.0.0/24") and functions to match if a given address is inside the range or not. Only IPv4 addresses are supported.

of_string Generates a Cidr.t based on a string like "10.0.0.0/8". Addresses are not expanded, i.e. "10/8" is invalid.

IPv4 multicast address can be represented by the CIDR prefix 224.0.0.0/4, (i.e. addreses from 224.0.0.0 to 239.255.255.255, inclusive)

Is the given address inside the given Cidr.t? Note that the broadcast and network addresses are considered valid so does_match 10.0.0.0/8 10.0.0.0 is true.

Sockets

val bin_socket_domain : socket_domain Core_kernel.Std.Bin_prot.Type_class.t
The type of socket domains.
val bin_read_socket_domain : socket_domain Core_kernel.Std.Bin_prot.Read_ml.reader
val bin_read_socket_domain_ : socket_domain Core_kernel.Std.Bin_prot.Unsafe_read_c.reader
val bin_read_socket_domain__ : (int -> socket_domain)
       Core_kernel.Std.Bin_prot.Unsafe_read_c.reader
val bin_reader_socket_domain : socket_domain Core_kernel.Std.Bin_prot.Type_class.reader
val bin_size_socket_domain : socket_domain Core_kernel.Std.Bin_prot.Size.sizer
val bin_write_socket_domain : socket_domain Core_kernel.Std.Bin_prot.Write_ml.writer
val bin_write_socket_domain_ : socket_domain Core_kernel.Std.Bin_prot.Unsafe_write_c.writer
val bin_writer_socket_domain : socket_domain Core_kernel.Std.Bin_prot.Type_class.writer
val socket_domain_of_sexp : Sexplib.Sexp.t -> socket_domain
val sexp_of_socket_domain : socket_domain -> Sexplib.Sexp.t
val bin_socket_type : socket_type Core_kernel.Std.Bin_prot.Type_class.t
The type of socket kinds, specifying the semantics of communications.
val bin_read_socket_type : socket_type Core_kernel.Std.Bin_prot.Read_ml.reader
val bin_read_socket_type_ : socket_type Core_kernel.Std.Bin_prot.Unsafe_read_c.reader
val bin_read_socket_type__ : (int -> socket_type) Core_kernel.Std.Bin_prot.Unsafe_read_c.reader
val bin_reader_socket_type : socket_type Core_kernel.Std.Bin_prot.Type_class.reader
val bin_size_socket_type : socket_type Core_kernel.Std.Bin_prot.Size.sizer
val bin_write_socket_type : socket_type Core_kernel.Std.Bin_prot.Write_ml.writer
val bin_write_socket_type_ : socket_type Core_kernel.Std.Bin_prot.Unsafe_write_c.writer
val bin_writer_socket_type : socket_type Core_kernel.Std.Bin_prot.Type_class.writer
val socket_type_of_sexp : Sexplib.Sexp.t -> socket_type
val sexp_of_socket_type : socket_type -> Sexplib.Sexp.t
val bin_sockaddr : sockaddr Core_kernel.Std.Bin_prot.Type_class.t
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 bin_read_sockaddr : sockaddr Core_kernel.Std.Bin_prot.Read_ml.reader
val bin_read_sockaddr_ : sockaddr Core_kernel.Std.Bin_prot.Unsafe_read_c.reader
val bin_read_sockaddr__ : (int -> sockaddr) Core_kernel.Std.Bin_prot.Unsafe_read_c.reader
val bin_reader_sockaddr : sockaddr Core_kernel.Std.Bin_prot.Type_class.reader
val bin_size_sockaddr : sockaddr Core_kernel.Std.Bin_prot.Size.sizer
val bin_write_sockaddr : sockaddr Core_kernel.Std.Bin_prot.Write_ml.writer
val bin_write_sockaddr_ : sockaddr Core_kernel.Std.Bin_prot.Unsafe_write_c.writer
val bin_writer_sockaddr : sockaddr Core_kernel.Std.Bin_prot.Type_class.writer
val sockaddr_of_sexp : Sexplib.Sexp.t -> sockaddr
val sexp_of_sockaddr : sockaddr -> Sexplib.Sexp.t

Return the socket domain adequate for the given socket address.

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.

Create a pair of unnamed sockets, connected together.

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.

Bind a socket to an address.

Connect a socket to an address.

Set up a socket for receiving connection requests. The integer argument is the maximal number of pending requests.
val shutdown_command_of_sexp : Sexplib.Sexp.t -> shutdown_command
The type of commands for shutdown.
val sexp_of_shutdown_command : shutdown_command -> Sexplib.Sexp.t
Close both

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).

Return the address of the given socket.

Return the address of the host connected to the given socket.
val msg_flag_of_sexp : Sexplib.Sexp.t -> msg_flag
The flags for UnixLabels.recv, UnixLabels.recvfrom, UnixLabels.send and UnixLabels.sendto.
val sexp_of_msg_flag : msg_flag -> Sexplib.Sexp.t

Receive data from an unconnected socket.

Receive data from an unconnected socket.

Send data over an unconnected socket.

Send data over an unconnected socket.

Socket options

val socket_bool_option_of_sexp : Sexplib.Sexp.t -> socket_bool_option
The socket options that can be consulted with UnixLabels.getsockopt and modified with UnixLabels.setsockopt. These options have a boolean (true/false) value.
val sexp_of_socket_bool_option : socket_bool_option -> Sexplib.Sexp.t
Forbid binding an IPv6 socket to an IPv4 address
val socket_int_option_of_sexp : Sexplib.Sexp.t -> socket_int_option
The socket options that can be consulted with UnixLabels.getsockopt_int and modified with UnixLabels.setsockopt_int. These options have an integer value.
val sexp_of_socket_int_option : socket_int_option -> Sexplib.Sexp.t

The socket options that can be consulted with UnixLabels.getsockopt_optint and modified with UnixLabels.setsockopt_optint. These options have a value of type int option, with None meaning ``disabled''.

Whether to linger on closed connections with sexp that have data present, and for how long (in seconds)
val socket_float_option_of_sexp : Sexplib.Sexp.t -> socket_float_option
The socket options that can be consulted with UnixLabels.getsockopt_float and modified with UnixLabels.setsockopt_float. These options have a floating-point value representing a time in seconds. The value 0 means infinite timeout.
val sexp_of_socket_float_option : socket_float_option -> Sexplib.Sexp.t
Timeout for output operations

Return the current status of a boolean-valued option in the given socket.

Set or clear a boolean-valued option in the given socket.

Same as UnixLabels.getsockopt for an integer-valued socket option.

Same as UnixLabels.setsockopt for an integer-valued socket option.

Same as UnixLabels.getsockopt for a socket option whose value is an int option.

Same as UnixLabels.setsockopt for a socket option whose value is an int option.

Same as UnixLabels.getsockopt for a socket option whose value is a floating-point number.

Same as UnixLabels.setsockopt for a socket option whose value is a floating-point number.

High-level network connection functions


Connect to a server at the given address. Return a pair of buffered channels connected to the server. Remember to call Pervasives.flush on the output channel at the right times to ensure correct synchronization.

``Shut down'' a connection established with UnixLabels.open_connection; that is, transmit an end-of-file condition to the server reading on the other side of the connection.

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 UnixLabels.establish_server never returns normally.

Host and protocol databases


Return the name of the local host.

Structure of entries in the hosts database.

Find an entry in hosts with the given name.

NOTE: This function is not thread safe with certain versions of winbind using "wins" name resolution.

Find an entry in hosts with the given address.

Structure of entries in the protocols database.

Find an entry in protocols with the given name.

Find an entry in protocols with the given protocol number.

Structure of entries in the services database.

Find an entry in services with the given name.

Find an entry in services with the given service number.

val addr_info_of_sexp : Sexplib.Sexp.t -> addr_info
Address information returned by Unix.getaddrinfo.
val sexp_of_addr_info : addr_info -> Sexplib.Sexp.t
val getaddrinfo_option_of_sexp : Sexplib.Sexp.t -> getaddrinfo_option
Options to Unix.getaddrinfo.
val sexp_of_getaddrinfo_option : getaddrinfo_option -> Sexplib.Sexp.t

getaddrinfo host service opts returns a list of Unix.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).

val name_info_of_sexp : Sexplib.Sexp.t -> name_info
Host and service information returned by Unix.getnameinfo.
val sexp_of_name_info : name_info -> Sexplib.Sexp.t
Name of service or port number
val getnameinfo_option_of_sexp : Sexplib.Sexp.t -> getnameinfo_option
Options to Unix.getnameinfo.
val sexp_of_getnameinfo_option : getnameinfo_option -> Sexplib.Sexp.t

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. Raise Not_found if an error occurs.

Getting terminal size



Terminal interface


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.

Ignore the break condition.

Signal interrupt on break condition.

Ignore characters with parity errors.

Mark parity errors.

Enable parity check on input.

Strip 8th bit on input characters.

Map NL to CR on input.

Ignore CR on input.

Map CR to NL on input.

Recognize XON/XOFF characters on input.

Emit XON/XOFF chars to control input flow.

Enable output processing.

Output baud rate (0 means close connection).

Input baud rate.

Number of bits per character (5-8).

Number of stop bits (1-2).

Reception is enabled.

Enable parity generation and detection.

Specify odd parity instead of even.

Hang up on last close.

Ignore modem status lines.

Generate signal on INTR, QUIT, SUSP.

Enable canonical processing (line buffering and editing)

Disable flush after INTR, QUIT, SUSP.

Echo input characters.

Echo ERASE (to erase previous character).

Echo KILL (to erase the current line).

Echo NL even if c_echo is not set.

Interrupt character (usually ctrl-C).

Quit character (usually ctrl-\).

Erase character (usually DEL or ctrl-H).

Kill line character (usually ctrl-U).

End-of-file character (usually ctrl-D).

Alternate end-of-line char. (usually none).

Minimum number of characters to read before the read request is satisfied.

Maximum read wait (in 0.1s units).

Start character (usually ctrl-Q).

Stop character (usually ctrl-S).

Return the status of the terminal referred to by the given file descriptor.

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.

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).

Waits until all output written on the given file descriptor has been transmitted.

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.

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.

Put the calling process in a new session and detach it from its controlling terminal.

Get a sockaddr from a hostname or IP, and a port

Set a timeout for a socket associated with an in_channel

Set a timeout for a socket associated with an out_channel

exit_immediately exit_code immediately calls the exit system call with the given exit code without performing any other actions (unlike Pervasives.exit). Does not return.

Filesystem functions



mknod ?file_kind ?perm ?major ?minor path creates a filesystem entry. Note that only FIFO-entries are guaranteed to be supported across all platforms as required by the POSIX-standard. On Linux directories and symbolic links cannot be created with this function. Use Unix.mkdir and Unix.symlink instead there respectively.

I/O vectors



I/O-vectors for scatter/gather-operations

Representation of I/O-vectors. NOTE: DO NOT CHANGE THE MEMORY LAYOUT OF THIS TYPE!!! All C-functions in our bindings that handle I/O-vectors depend on it.

Buffer holding the I/O-vector

Position of I/O-vector in buffer

Length of I/O-vector in buffer

Kind of I/O-vector buffers

empty the empty I/O-vector.

of_string ?pos ?len str

of_bigstring ?pos ?len bstr

drop iovec n drops n characters from iovec.

I/O functions



Extract a file descriptor from a directory handle.

Synchronize all filesystem buffers with disk.

Synchronize the kernel buffers of a given file descriptor with disk, but do not necessarily write file attributes.

readdir_ino dh return the next entry in a directory (((filename, inode)).

read_assume_fd_is_nonblocking fd ?pos ?len buf calls the system call read ASSUMING THAT IT IS NOT GOING TO BLOCK. Reads at most len bytes into buffer buf starting at position pos.

write_assume_fd_is_nonblocking fd ?pos ?len buf calls the system call write ASSUMING THAT IT IS NOT GOING TO BLOCK. Writes at most len bytes from buffer buf starting at position pos.

writev_assume_fd_is_nonblocking fd ?count iovecs calls the system call writev ASSUMING THAT IT IS NOT GOING TO BLOCK using count I/O-vectors iovecs.

writev fd ?count iovecs like Unix.writev_assume_fd_is_nonblocking, but does not require the descriptor to not block. If you feel you have to use this function, you should probably have chosen I/O-vectors that build on bigstrings, because this function has to internally blit the I/O-vectors (ordinary OCaml strings) to intermediate buffers on the C-heap.

pselect rfds wfds efds timeout sigmask like Unix.select but also allows one to wait for the arrival of signals.

Resource limits



Resource usage

-- For details, "man getrusage"

add ru1 ru2 adds two rusage structures (e.g. your resource usage and your children's).
val sysconf_of_sexp : Sexplib.Sexp.t -> sysconf

System configuration


val sexp_of_sysconf : sysconf -> Sexplib.Sexp.t

Temporary file and directory creation



mkstemp prefix creates and opens a unique temporary file with prefix, automatically appending a suffix of six random characters to make the name unique. Unlike C's mkstemp, prefix should not include six X's at the end.

mkdtemp prefix creates a temporary directory with prefix, automatically appending a suffix of six random characters to make the name unique.

Signal handling



User id, group id



getgrouplist user group returns the list of groups to which user belongs. See 'man getgrouplist'.

Return the list of groups to which the user executing the process belongs.

Globbing and shell expansion



System information



Additional IP functionality



mcast_join ?ifname sock addr join a multicast group at addr with socket sock, optionally using network interface ifname.

mcast_leave ?ifname sock addr leaves a multicast group at addr with socket sock, optionally using network interface ifname.

get_mcast_ttl sock reads the time-to-live value of outgoing multicast packets for socket sock.

set_mcast_ttl sock ttl sets the time-to-live value of outgoing multicast packets for socket sock to ttl.

get_mcast_loop sock reads the boolean argument that determines whether sent multicast packets are looped back to local sockets.

set_mcast_loop sock loop sets the boolean argument that determines whether sent multicast packets are looped back to local sockets.