Lua에 파일이 있는지 확인

Lua에 파일이 있는지 확인

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Lua를 사용하여 파일이 있는지 어떻게 확인할 수 있습니까?

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시험

function file_exists(name)
   local f=io.open(name,"r")
   if f~=nil then io.close(f) return true else return false end
end

그러나이 코드는 파일을 읽기 위해 열 수 있는지 여부 만 테스트합니다.

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일반 Lua를 사용하면 LHF에 따라 파일을 읽기 위해 열 수 있는지 확인하는 것이 가장 좋습니다. 이것은 거의 항상 충분합니다. 그러나 더 많은 것을 원한다면 Lua POSIX 라이브러리를 로드하고 posix.stat(경로) 가 non-를 반환 하는지 확인하십시오 nil.

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여기 에서 인용 하겠습니다

나는 이것을 사용하지만 실제로 오류를 확인합니다.

require("lfs")
-- no function checks for errors.
-- you should check for them

function isFile(name)
    if type(name)~="string" then return false end
    if not isDir(name) then
        return os.rename(name,name) and true or false
        -- note that the short evaluation is to
        -- return false instead of a possible nil
    end
    return false
end

function isFileOrDir(name)
    if type(name)~="string" then return false end
    return os.rename(name, name) and true or false
end

function isDir(name)
    if type(name)~="string" then return false end
    local cd = lfs.currentdir()
    local is = lfs.chdir(name) and true or false
    lfs.chdir(cd)
    return is
end

os.rename (name1, name2)는 name1의 이름을 name2로 바꿉니다. 동일한 이름을 사용하고 아무것도 변경해서는 안됩니다 (악성 오류가있는 경우 제외). 모든 것이 잘 작동하면 true를 반환하고 그렇지 않으면 nil과 오류 메시지를 반환합니다. lfs를 사용하지 않으려면 파일을 열지 않고 파일과 디렉토리를 구분할 수 없습니다 (약간 느리지 만 괜찮습니다).

그래서 LuaFileSystem없이

-- no require("lfs")

function exists(name)
    if type(name)~="string" then return false end
    return os.rename(name,name) and true or false
end

function isFile(name)
    if type(name)~="string" then return false end
    if not exists(name) then return false end
    local f = io.open(name)
    if f then
        f:close()
        return true
    end
    return false
end

function isDir(name)
    return (exists(name) and not isFile(name))
end

짧아 보이지만 시간이 오래 걸립니다 ... 파일을 여는 것도 위험합니다

즐겁게 코딩하세요!

---

Premake 및 LUA 버전 5.3.4를 사용하는 경우 :

if os.isfile(path) then
    ...
end

---

완전성을 위해 :를 사용하여 운을 시험해 볼 수도 있습니다 path.exists(filename). 어떤 Lua 배포판에 실제로이 path네임 스페이스 ( update : Penlight ) 가 있는지 확실하지 않지만 적어도 Torch에 포함되어 있습니다.

$ th

  ______             __   |  Torch7
 /_  __/__  ________/ /   |  Scientific computing for Lua.
  / / / _ \/ __/ __/ _ \  |  Type ? for help
 /_/  \___/_/  \__/_//_/  |  https://github.com/torch
                          |  http://torch.ch

th> path.exists(".gitignore")
.gitignore  

th> path.exists("non-existing")
false   

debug.getinfo(path.exists) tells me that its source is in torch/install/share/lua/5.1/pl/path.lua and it is implemented as follows:

--- does a path exist?.
-- @string P A file path
-- @return the file path if it exists, nil otherwise
function path.exists(P)
    assert_string(1,P)
    return attrib(P,'mode') ~= nil and P
end

---

If you are willing to use lfs, you can use lfs.attributes. It will return nil in case of error:

require "lfs"

if lfs.attributes("non-existing-file") then
    print("File exists")
else
    print("Could not get attributes")
end

Although it can return nil for other errors other than a non-existing file, if it doesn't return nil, the file certainly exists.

---

An answer which is windows only checks for files and folders, and also requires no additional packages. It returns true or false.

io.popen("if exist "..PathToFileOrFolder.." (echo 1)"):read'*l'=='1'

io.popen(...):read'*l' - executes a command in the command prompt and reads the result from the CMD stdout

if exist - CMD command to check if an object exists

(echo 1) - prints 1 to stdout of the command prompt

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You can also use the 'paths' package. Here's the link to the package

Then in Lua do:

require 'paths'

if paths.filep('your_desired_file_path') then
    print 'it exists'
else
    print 'it does not exist'
end

---

Not necessarily the most ideal as I do not know your specific purpose for this or if you have a desired implementation in mind, but you can simply open the file to check for its existence.

local function file_exists(filename)
    local file = io.open(filename, "r")
    if (file) then
        -- Obviously close the file if it did successfully open.
        file:close()
        return true
    end
    return false
end

io.open returns nil if it fails to open the file. As a side note, this is why it is often used with assert to produce a helpful error message if it is unable to open the given file. For instance:

local file = assert(io.open("hello.txt"))

If the file hello.txt does not exist, you should get an error similar to stdin:1: hello.txt: No such file or directory.

---

Lua 5.1:

function file_exists(name)
   local f = io.open(name, "r")
   return f ~= nil and io.close(f)
end

---

For library solution, you can use either paths or path.

From the official document of paths:

paths.filep(path)

Return a boolean indicating whether path refers to an existing file.

paths.dirp(path)

Return a boolean indicating whether path refers to an existing directory.

Although the names are a little bit strange, you can certainly use paths.filep() to check whether a path exists and it is a file. Use paths.dirp() to check whether it exists and it is a directory. Very convenient.

If you prefer path rather than paths, you can use path.exists() with assert() to check the existence of a path, getting its value at the same time. Useful when you are building up path from pieces.

prefix = 'some dir'

filename = assert(path.exist(path.join(prefix, 'data.csv')), 'data.csv does not exist!')

If you just want to check the boolean result, use path.isdir() and path.isfile(). Their purposes are well-understood from their names.

---

How about doing something like this?

function exist(file)
  local isExist = io.popen(
    '[[ -e '.. tostring(file) ..' ]] && { echo "true"; }')
  local isIt = isExist:read("*a")
  isExist:close()
  isIt = string.gsub(isIt, '^%s*(.-)%s*$', '%1')
  if isIt == "true" then
    return true
  end
end

if exist("myfile") then
  print("hi, file exists")
else
  print("bye, file does not exist")
end

---

IsFile = function(path)
print(io.open(path or '','r')~=nil and 'File exists' or 'No file exists on this path: '..(path=='' and 'empty path entered!' or (path or 'arg "path" wasn\'t define to function call!')))
end

IsFile()
IsFile('')
IsFIle('C:/Users/testuser/testfile.txt')

Looks good for testing your way. :)

참고URL : https://stackoverflow.com/questions/4990990/check-if-a-file-exists-with-lua