Difference between revisions of "Fs.open"
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|api=fs | |api=fs | ||
|desc=Closes the file handle, after which it can no longer be used | |desc=Closes the file handle, after which it can no longer be used | ||
+ | }} | ||
+ | |||
+ | === Saving a file without closing it === | ||
+ | if you just want to save a file, without closing the handle, then you could do a flush. ( this is normally used for logging etc...) | ||
+ | {{Function | ||
+ | |name=<var>h</var>.flush | ||
+ | |api=fs | ||
+ | |desc=Flushes the data to the specified file. (keeps the handle available afterwards) | ||
}} | }} | ||
Revision as of 16:14, 16 October 2013
Function fs.open | |
Supported File Modes
Opens a file so it can be read or written. mode consists of a first character which is one of the following:
optionally followed by "b" to open the file for binary access instead of text access (text mode will perform end-of-line conversions necessary to move text files between Windows, Linux, and Mac OS systems; binary files should not have these conversions applied as they will be corrupted) When you have opened a file you must always close the file handle, or else data will not be saved. | |
Syntax | fs.open(string path, string mode) |
Returns | table the file handle, or nil on error (e.g. if mode was "r" and the file did not exist, or if mode was "w" or "a" and the file was in a read-only location) |
Part of | ComputerCraft |
API | fs |
Contents
Examples
Example | |
Creates the file "abcd" for writing, and holds a file handle to it | |
Code |
h = fs.open("abcd", "w") |
File Handles
A file handle allows access to a file. A file handle is a table; the functions within the table are accessed with the dot operator (not the colon operator, as may be more intuitive!). The examples below assume a file has already been opened and the handle stored in the variable h.
Closing a file handle
When you open a file you must remember to then close the handle! With the write modes supported by ComputerCraft all the data that you are writing to a file will not be written into the file until you close the file. A file opened in any mode exposes the following close function.
Function h.close | |
Closes the file handle, after which it can no longer be used | |
Syntax | h.close() |
Returns | nil |
Part of | ComputerCraft |
API | fs |
Saving a file without closing it
if you just want to save a file, without closing the handle, then you could do a flush. ( this is normally used for logging etc...)
Function h.flush | |
Flushes the data to the specified file. (keeps the handle available afterwards) | |
Syntax | h.flush() |
Returns | nil |
Part of | ComputerCraft |
API | fs |
Files opened in text read mode
A file opened in mode "r" (text read mode) exposes the following functions.
Function h.readLine | |
Reads the next line from the file | |
Syntax | h.readLine() |
Returns | string the next line read from the file, with the end-of-line character stripped; or nil if there are no more lines in the file |
Part of | ComputerCraft |
API | fs |
Function h.readAll | |
Reads the all the text in the file | |
Syntax | h.readAll() |
Returns | string the entire rest of the file, with the end-of-line character on the very last line (if present) stripped |
Part of | ComputerCraft |
API | fs |
Files opened in text write/append mode
A file opened in mode "w" (text write mode) or "a" (text append mode) exposes the following functions:
Function h.write | |
Writes a string of characters to the file exactly as they appear in the string data | |
Syntax | h.write(string data) |
Returns | nil |
Part of | ComputerCraft |
API | fs |
Function h.writeLine | |
Writes a string of characters to the file, then appends an end-of-line character | |
Syntax | h.writeLine(string data) |
Returns | nil |
Part of | ComputerCraft |
API | fs |
Files opened in binary read mode
A file opened in mode "rb" (binary read mode) exposes the following functions:
Function h.read | |
Reads a single byte from the file and returns it | |
Syntax | h.read() |
Returns | number the byte read from the file, or nil if there are no more bytes |
Part of | ComputerCraft |
API | fs |
Files opened in binary write/append mode
A file opened in mode "wb" (binary write mode) or "ab" (binary append mode) exposes the following functions:
Function h.write | |
Writes a single byte into the file | |
Syntax | h.write(number byte) |
Returns | nil |
Part of | ComputerCraft |
API | fs |