Transferred file module documentation.

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# file Module
The file module provides access to the file system and its individual files.
The file system is a flat file system, with no notion of directories/folders.
Only one file can be open at any given time.
## file.fsinfo()
Return size information for the file system, in bytes.
####Syntax
`file.fsinfo()`
####Parameters
`nil`
####Returns
- `remaining` (number)
- `used` (number)
- `total` (number)
####Example
```lua
-- get file system info
remaining, used, total=file.fsinfo()
print("\nFile system info:\nTotal : "..total.." Bytes\nUsed : "..used.." Bytes\nRemain: "..remaining.." Bytes\n")
```
```
___
## file.format()
Format the file system. Completely erases any existing file system and writes a new one. Depending on the size of the flash chip in the ESP, this may take several seconds.
####Syntax
`file.format()`
####Parameters
`nil`
####Returns
`nil`
####Example
```lua
file.format()
```
####See also
- `file.remove()`
___
## file.list()
Lists all files in the file system.
####Syntax
`file.list()`
####Parameters
`nil`
####Returns
a lua table which contains the {file name: file size} pairs
####Example
```lua
l = file.list();
for k,v in pairs(l) do
print("name:"..k..", size:"..v)
end
```
___
## file.remove()
Remove a file from the file system. The file must not be currently open.
###Syntax
`file.remove(filename)`
####Parameters
- `filename`: file to remove
####Returns
`nil`
####Example
```lua
-- remove "foo.lua" from file system.
file.remove("foo.lua")
```
####See also
- `file.open()`
___
## file.rename()
Renames a file. If a file is currently open, it will be closed first.
####Syntax
`file.rename(oldname, newname)`
####Parameters
- `oldname`: old file name
- `newname`: new file name
####Returns
`true` on success, `false` on error.
####Example
```lua
-- rename file 'temp.lua' to 'init.lua'.
file.rename("temp.lua","init.lua")
```
___
## file.open()
Opens a file for access, potentially creating it (for write modes).
When done with the file, it must be closed using `file.close()`.
####Syntax
`file.open(filename, mode)`
####Parameters
- `filename`: file to be opened, directories are not supported
- `mode`:
- "r": read mode (the default)<br />
- "w": write mode<br />
- "a": append mode<br />
- "r+": update mode, all previous data is preserved<br />
- "w+": update mode, all previous data is erased<br />
- "a+": append update mode, previous data is preserved, writing is only allowed at the end of file
####Returns
- `nil` if file not opened, or not exists (read modes). true` if file opened ok.
####Example
```lua
-- open 'init.lua', print the first line.
file.open("init.lua", "r")
print(file.readline())
file.close()
```
####See also
- `file.close()`
- `file.readline()`
___
## file.close()
Closes the open file, if any.
####Syntax
`file.close()`
####Parameters
`nil`
####Returns
`nil`
####Example
```lua
-- open 'init.lua', print the first line.
file.open("init.lua", "r")
print(file.readline())
file.close()
```
####See also
- `file.open()`
___
## file.readline()
Read the next line from the open file.
####Syntax
`file.readline()`
####Parameters
`nil`
####Returns
File content in string, line by line, include EOL('\n'). Return `nil` when EOF.
####Example
```lua
-- print the first line of 'init.lua'
file.open("init.lua", "r")
print(file.readline())
file.close()
```
####See also
- `file.open()`
- `file.close()`
- `file.read()`
___
## file.writeline()
Write a string to the open file and append '\n' at the end.
####Syntax
`file.writeline(string)`
####Parameters
- `string`: content to be write to file
####Returns
`true` if write ok, `nil` on error.
####Example
```lua
-- open 'init.lua' in 'a+' mode
file.open("init.lua", "a+")
-- write 'foo bar' to the end of the file
file.writeline('foo bar')
file.close()
```
####See also
- `file.open()`
- `file.readline()`
___
## file.read()
Read content from the open file.
####Syntax
`file.read([n_or_str])`
####Parameters
- `n_or_str`:
- if nothing passed in, read all byte in file.
- if pass a number n, then read n bytes from file, or EOF is reached.
- if pass a string "str", then read until 'str' or EOF is reached.
####Returns
File content in string, or nil when EOF.
####Example
```lua
-- print the first line of 'init.lua'
file.open("init.lua", "r")
print(file.read('\n'))
file.close()
-- print the first 5 byte of 'init.lua'
file.open("init.lua", "r")
print(file.read(5))
file.close()
```
####See also
- `file.open()`
- `file.readline()`
___
## file.write()
Write a string to the open file.
####Syntax
`file.write(string)`
####Parameters
`string`: content to be write to file.
####Returns
`true` if the write is ok, `nil` on error.
####Example
```lua
-- open 'init.lua' in 'a+' mode
file.open("init.lua", "a+")
-- write 'foo bar' to the end of the file
file.write('foo bar')
file.close()
```
####See also
- `file.open()`
- `file.writeline()`
___
## file.flush()
Flushes any pending writes to the file system, ensuring no data is lost on a restart. Closing the open file using `file.close()` performs an implicit flush as well.
####Syntax
`file.flush()`
####Parameters
`nil`
####Returns
`nil`
####Example
```lua
-- open 'init.lua' in 'a+' mode
file.open("init.lua", "a+")
-- write 'foo bar' to the end of the file
file.write('foo bar')
file.flush()
-- write 'baz' too
file.write('baz')
file.close()
```
####See also
- `file.close()`
___
## file.seek()
Sets and gets the file position, measured from the beginning of the file, to the position given by offset plus a base specified by the string whence.
####Syntax
`file.seek([whence [, offset]])`
####Parameters
- `whence`:
- "set": base is position 0 (beginning of the file)
- "cur": base is current position (default value)
- "end": base is end of file
- offset: default 0
If no parameters are given, the function simply returns the current file offset.
####Returns
The resulting file position, or `nil` on error.
####Example
```lua
file.open("init.lua", "r")
-- skip the first 5 bytes of the file
file.seek("set", 5)
print(file.readline())
file.close()
```
####See also
- `file.open()`
___

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@ -30,5 +30,6 @@ pages:
- Support: 'en/support.md' - Support: 'en/support.md'
- Modules: - Modules:
- 'node': 'en/modules/node.md' - 'node': 'en/modules/node.md'
- 'file': 'en/modules/file.md'
- Deutsch: - Deutsch:
- Home: 'de/index.md' - Home: 'de/index.md'