file模块¶

consult/1¶

结构:

% 获取指定文件的内容
% 只能打开erl文件？
consult(Filename) -> {ok, Terms} | {error, Reason}
%Reason =
%  posix() |
%  badarg |
%  terminated |
%  system_limit |
%  {Line :: integer(), Mod :: module(), Term :: term()}

open/2¶

结构:

open(File, Modes) -> {ok, IoDevice} | {error, Reason}
类型:
File = Filename | iodata()
  Filename = name_all()
Modes = [mode() | ram]
IoDevice = io_device()
Reason = posix() | badarg | system_limit

mode:

read |
write |
append |
exclusive |
raw |         % 1.允许更快的access
              % 2.只有打开这个文件的erlang进程可用
              % 3.远程节点不可用(必须有文件系统权限)
binary |
{delayed_write, Size, Delay} |  % 数据延时执行write/2操作
                                % 1.数据大小超过Size bytes
                                % 2.时间超过Delay milliseconds
delayed_write |
{read_ahead, Size} |
read_ahead |
compressed |
{encoding, unicode:encoding()} |
sync

read_file_info/1/2¶

结构:

read_file_info(Filename) -> {ok, FileInfo} | {error, Reason}
read_file_info(Filename, Opts) -> {ok, FileInfo} | {error, Reason}
类型:
Filename = name_all()
Opts = [file_info_option()]
FileInfo = file_info()
Reason = posix() | badarg

Opts类型:

{time, local} |       % [default]
{time, universal} |
{time, posix} |       % Returns seconds since or before Unix time epoch
raw                   % 不调用file服务,只有local files的信息

file_info()返回值:

格式: #file_info{}
来源:kernel/include/file.hrl
结构:
  size  % Size of file in bytes.
  type  % 'device' | 'directory' | 'other' | 'regular' | 'symlink' | 'undefined',
  access % 'read' | 'write' | 'read_write' | 'none' | 'undefined',
  atime  % The local time the file was last read:
         % {{Year, Mon, Day}, {Hour, Min, Sec}}.
  mtime  % The local time the file was last written.
  ctime  % On Unix it is the last time the file or the inode was changed.
         % On Windows, it is the creation time.
  mode   % File permissions.
  links  % Number of links to the file
  major_device  % Identifies the file system (Unix),
                % the drive number (A: = 0, B: = 1) (Windows).
  %% The following are Unix specific.
  %% They are set to 0 on other operating systems.
  minor_device  % Only valid for devices.
  inode    % Inode number for file.
  uid      % uid
  gid      % gid

read/2¶

结构:

read(IoDevice, Number) -> {ok, Data} | eof | {error, Reason}
类型:
IoDevice = io_device() | atom()
Number = integer() >= 0
Data = string() | binary()
Reason =
    posix() |
    badarg |
    terminated |
    {no_translation, unicode, latin1}

说明:

其中Number可用filelib:file_size(FilePath)获取

实例¶

打开文件并读取其中内容:

64> {ok,File}=file:open("fibo.erl",[raw,read]).
65> {ok,Data}=file:read(File,filelib:file_size("fibo.erl")).