package core_unix

File descriptor.

• deprecated [since 2016-10] use [Unix.Error.t] instead

• deprecated [since 2016-10] use [Unix.Error.t] instead

• deprecated [since 2016-10] use [Unix.Error.t] instead

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.

Representation of Unix system call results

• raises Unix_error

  with a given errno, function name and argument

• deprecated [since 2016-10] use [Unix.Error.message] instead

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.

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.

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.

The termination status of a process.

this module mirrors Spawn.Pgid

exec ~prog ~argv ?search_path ?env execs prog with argv. 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 determines the environment when prog is executed.

While not strictly necessary, by convention, the first element in argv should be the name of the file being executed, e.g.:

exec ~prog ~argv:[ prog; arg1; arg2; ...] () 

fork_exec ~prog ~argv ?use_path ?env () forks and execs prog with argv in the child process, returning the child PID to the parent. As in exec, by convention, the 0th element in argv should be the program itself.

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.

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.

Set process group ID of a process.

Return process group ID of a process.

Get the numeric ID of the current thread, e.g. for identifying it in top(1).

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.

File descriptor for standard input.

File descriptor for standard output.

File descriptor for standard standard error.

We can't use with sexp because pa_sexp inserts two copies of the val specs, which leads to a spurious "unused" warning.

file access rights

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.

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, async, direct, noatime, 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 bytes buff, starting at position ofs in bytes 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 with a string buffer.

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

Same as single_write but with a string buffer.

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.

POSITIONING modes for UnixLabels.lseek.

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.

The informations returned by the UnixLabels.stat calls. The times are float number of seconds since the epoch; we don't use Time.t because Time depends on Unix, so the fix isn't so trivial. Same for Native_file.stats below.

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.

This sub-module provides the normal OCaml Unix functions that deal with file size using native ints. These are here because, in general, you should be using 64bit file operations so that large files aren't an issue. If you have a real need to use potentially 31bit file operations (and you should be dubious of such a need) you can open this module

Commands for lockf.

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.

Note that, despite the name, this function does not call the UNIX lockf() system call; rather it calls fcntl() with one of F_SETLK, F_SETLKW, or F_GETLK.

flock fd cmd places or releases a lock on the fd as per the flock C call of the same name. The request is "nonblocking" (LOCK_NB in C), meaning that if the lock cannot be granted immediately, the return value is false. However, the system call still blocks until the lock status can be ascertained. true is returned if the lock was granted.

flock_blocking fd cmd places or releases a lock on the fd as per the flock C call. The function does not return until a lock can be granted.

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

Memory mapping of a file as a big array. map_file fd kind layout ~shared dims returns a big array of kind kind, layout layout, and dimensions as specified in dims.

The data contained in this big array are the contents of the file referred to by the file descriptor fd.

The optional pos parameter is the byte offset in the file of the data being mapped. It defaults to 0.

If shared is true, all modifications performed on the array are reflected in the file. This requires that fd be opened with write permissions. If shared is false, modifications performed on the array are done in memory only, using copy-on-write of the modified pages; the underlying file is not affected.

To adjust automatically the dimensions of the big array to the actual size of the file, the major dimension (that is, the first dimension for an array with C layout, and the last dimension for an array with Fortran layout) can be given as -1. map_file then determines the major dimension from the size of the file. The file must contain an integral number of sub-arrays as determined by the non-major dimensions, otherwise Failure is raised. If all dimensions of the big array are given, the file size is matched against the size of the big array. If the file is larger than the big array, only the initial portion of the file is mapped to the big array. If the file is smaller than the bigarray, the file is automatically grown to the size of the big array. This requires write permissions on fd.

Array accesses are bounds-checked, but the bounds are determined by the initial call to map_file. Therefore, you should make sure no other process modifies the mapped file while you're accessing it, or a SIGBUS signal may be raised. This happens, for instance, if the file is shrunk. Invalid_argument or Failure may be raised in cases where argument validation fails.

• since 4.05.0

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.

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.

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

dup2 ~src ~dst duplicates src to dst, closing dst 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.

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. Returns None when the end of the directory has been reached.

Same as readdir_opt except that it signals the end of the directory by raising End_of_file.

• deprecated [since 2016-08] use [readdir_opt] instead

Reposition the descriptor to the beginning of the directory

Close a directory descriptor.

readdir_detailed_opt dh return the next entry in a directory. Returns None when the end of the directory has been reached.

ls_dir_detailed path returns the information from readdir_detailed_opt with an interface similar to that of Sys_unix.ls_dir.

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.

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.

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. If argv0 is given, it is used (instead of prog) as the first element of the argv array passed to execve.

The exact program to execute is determined using the usual conventions. More precisely, if prog contains at least one '/' character then it is used as is (relative to working_dir if prog is a relative path, absolute otherwise). Note that working_dir defaults to the working directory of the current process, i.e. getcwd (). If prog contains no '/' character, then it is looked up in prog_search_path: for the first dir in prog_search_path such that Filename.concat dir prog exists and is executable, Filename.concat dir prog is the program that will be executed.

prog_search_path defaults to the list of directories encoded as a ':' separated list in the "PATH" environment variable of the current running process. If no such variable is defined, then

["/bin"; "/usr/bin"]

is used instead. Note that the "PATH" environment variable is looked up in the environment of the current running process, i.e. via getenv "PATH". Setting the "PATH" variable in the env argument of this function has no effect on how prog is resolved.

In a setuid or setgid program, or one which has inherited such privileges, reading of the PATH variable will return an empty result. If a search path is required then it should be provided explicitly using prog_search_path in such scenarios; alternatively, perhaps more satisfactorily, an absolute path should be given as prog.

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 Caml.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.