package ocaml-base-compiler
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Interface to the Unix system.

To use the labeled version of this module, add module Unix = UnixLabels in your implementation.

Note: all the functions of this module (except error_message and handle_unix_error) are liable to raise the Unix_error exception whenever the underlying system call signals an error.

Error report

type error = Unix.error =
  1. | E2BIG
    (*

    Argument list too long

    *)
  2. | EACCES
    (*

    Permission denied

    *)
  3. | EAGAIN
    (*

    Resource temporarily unavailable; try again

    *)
  4. | EBADF
    (*

    Bad file descriptor

    *)
  5. | EBUSY
    (*

    Resource unavailable

    *)
  6. | ECHILD
    (*

    No child process

    *)
  7. | EDEADLK
    (*

    Resource deadlock would occur

    *)
  8. | EDOM
    (*

    Domain error for math functions, etc.

    *)
  9. | EEXIST
    (*

    File exists

    *)
  10. | EFAULT
    (*

    Bad address

    *)
  11. | EFBIG
    (*

    File too large

    *)
  12. | EINTR
    (*

    Function interrupted by signal

    *)
  13. | EINVAL
    (*

    Invalid argument

    *)
  14. | EIO
    (*

    Hardware I/O error

    *)
  15. | EISDIR
    (*

    Is a directory

    *)
  16. | EMFILE
    (*

    Too many open files by the process

    *)
  17. | ENAMETOOLONG
    (*

    Filename too long

    *)
  18. | ENFILE
    (*

    Too many open files in the system

    *)
  19. | ENODEV
    (*

    No such device

    *)
  20. | ENOENT
    (*

    No such file or directory

    *)
  21. | ENOEXEC
    (*

    Not an executable file

    *)
  22. | ENOLCK
    (*

    No locks available

    *)
  23. | ENOMEM
    (*

    Not enough memory

    *)
  24. | ENOSPC
    (*

    No space left on device

    *)
  25. | ENOSYS
    (*

    Function not supported

    *)
  26. | ENOTDIR
    (*

    Not a directory

    *)
  27. | ENOTEMPTY
    (*

    Directory not empty

    *)
  28. | ENOTTY
    (*

    Inappropriate I/O control operation

    *)
  29. | ENXIO
    (*

    No such device or address

    *)
  30. | EPERM
    (*

    Operation not permitted

    *)
  31. | EPIPE
    (*

    Broken pipe

    *)
  32. | ERANGE
    (*

    Result too large

    *)
  33. | EROFS
    (*

    Read-only file system

    *)
  34. | ESPIPE
    (*

    Invalid seek e.g. on a pipe

    *)
  35. | ESRCH
    (*

    No such process

    *)
  36. | EXDEV
    (*

    Invalid link

    *)
  37. | EWOULDBLOCK
    (*

    Operation would block

    *)
  38. | EINPROGRESS
    (*

    Operation now in progress

    *)
  39. | EALREADY
    (*

    Operation already in progress

    *)
  40. | ENOTSOCK
    (*

    Socket operation on non-socket

    *)
  41. | EDESTADDRREQ
    (*

    Destination address required

    *)
  42. | EMSGSIZE
    (*

    Message too long

    *)
  43. | EPROTOTYPE
    (*

    Protocol wrong type for socket

    *)
  44. | ENOPROTOOPT
    (*

    Protocol not available

    *)
  45. | EPROTONOSUPPORT
    (*

    Protocol not supported

    *)
  46. | ESOCKTNOSUPPORT
    (*

    Socket type not supported

    *)
  47. | EOPNOTSUPP
    (*

    Operation not supported on socket

    *)
  48. | EPFNOSUPPORT
    (*

    Protocol family not supported

    *)
  49. | EAFNOSUPPORT
    (*

    Address family not supported by protocol family

    *)
  50. | EADDRINUSE
    (*

    Address already in use

    *)
  51. | EADDRNOTAVAIL
    (*

    Can't assign requested address

    *)
  52. | ENETDOWN
    (*

    Network is down

    *)
  53. | ENETUNREACH
    (*

    Network is unreachable

    *)
  54. | ENETRESET
    (*

    Network dropped connection on reset

    *)
  55. | ECONNABORTED
    (*

    Software caused connection abort

    *)
  56. | ECONNRESET
    (*

    Connection reset by peer

    *)
  57. | ENOBUFS
    (*

    No buffer space available

    *)
  58. | EISCONN
    (*

    Socket is already connected

    *)
  59. | ENOTCONN
    (*

    Socket is not connected

    *)
  60. | ESHUTDOWN
    (*

    Can't send after socket shutdown

    *)
  61. | ETOOMANYREFS
    (*

    Too many references: can't splice

    *)
  62. | ETIMEDOUT
    (*

    Connection timed out

    *)
  63. | ECONNREFUSED
    (*

    Connection refused

    *)
  64. | EHOSTDOWN
    (*

    Host is down

    *)
  65. | EHOSTUNREACH
    (*

    No route to host

    *)
  66. | ELOOP
    (*

    Too many levels of symbolic links

    *)
  67. | EOVERFLOW
    (*

    File size or position not representable

    *)
  68. | EUNKNOWNERR of int
    (*

    Unknown error

    *)

The type of error codes. Errors defined in the POSIX standard and additional errors from UNIX98 and BSD. All other errors are mapped to EUNKNOWNERR.

exception Unix_error of error * string * string

Raised by the system calls below when an error is encountered. The first component is the error code; the second component is the function name; the third component is the string parameter to the function, if it has one, or the empty string otherwise.

UnixLabels.Unix_error and Unix.Unix_error are the same, and catching one will catch the other.

val error_message : error -> string

Return a string describing the given error code.

val handle_unix_error : ('a -> 'b) -> 'a -> 'b

handle_unix_error f x applies f to x and returns the result. If the exception Unix_error is raised, it prints a message describing the error and exits with code 2.

Access to the process environment

val environment : unit -> string array

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.

val unsafe_environment : unit -> string array

Return the process environment, as an array of strings with the format ``variable=value''. Unlike environment, this function returns a populated array even if the process has special privileges. See the documentation for unsafe_getenv for more details.

  • since 4.12.0
val getenv : string -> string

Return the value associated to a variable in the process environment, unless the process has special privileges.

  • raises Not_found

    if the variable is unbound or the process has special privileges.

    This function is identical to Sys.getenv.

val unsafe_getenv : string -> string

Return the value associated to a variable in the process environment.

Unlike getenv, this function returns the value even if the process has special privileges. It is considered unsafe because the programmer of a setuid or setgid program must be careful to avoid using maliciously crafted environment variables in the search path for executables, the locations for temporary files or logs, and the like.

  • raises Not_found

    if the variable is unbound.

  • since 4.06.0
val putenv : string -> string -> unit

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

Process handling

type process_status = Unix.process_status =
  1. | WEXITED of int
    (*

    The process terminated normally by exit; the argument is the return code.

    *)
  2. | WSIGNALED of int
    (*

    The process was killed by a signal; the argument is the signal number.

    *)
  3. | WSTOPPED of int
    (*

    The process was stopped by a signal; the argument is the signal number.

    *)

The termination status of a process. See module Sys for the definitions of the standard signal numbers. Note that they are not the numbers used by the OS.

type wait_flag = Unix.wait_flag =
  1. | WNOHANG
    (*

    Do not block if no child has died yet, but immediately return with a pid equal to 0.

    *)
  2. | WUNTRACED
    (*

    Report also the children that receive stop signals.

    *)

Flags for waitpid.

val execv : prog:string -> args:string array -> 'a

execv ~prog ~args execute the program in file prog, with the arguments args, and the current process environment. These execv* functions never return: on success, the current program is replaced by the new one.

  • raises Unix_error

    on failure

val execve : prog:string -> args:string array -> env:string array -> 'a

Same as execv, except that the third argument provides the environment to the program executed.

val execvp : prog:string -> args:string array -> 'a

Same as execv, except that the program is searched in the path.

val execvpe : prog:string -> args:string array -> env:string array -> 'a

Same as execve, except that the program is searched in the path.

val fork : unit -> int

Fork a new process. The returned integer is 0 for the child process, the pid of the child process for the parent process.

  • raises Invalid_argument

    on Windows. Use create_process or threads instead.

val wait : unit -> int * process_status

Wait until one of the children processes die, and return its pid and termination status.

  • raises Invalid_argument

    on Windows. Use waitpid instead.

val waitpid : mode:wait_flag list -> int -> int * process_status