25 Files

This chapter describes the Emacs Lisp functions and variables to find, create, view, save, and otherwise work with files and directories. A few other file-related functions are described in Buffers, and those related to backups and auto-saving are described in Backups and Auto-Saving.

Many of the file functions take one or more arguments that are file names. A file name is a string. Most of these functions expand file name arguments using the function expand-file-name, so that ~ is handled correctly, as are relative file names (including ../ and the empty string). See File Name Expansion.

In addition, certain magic file names are handled specially. For example, when a remote file name is specified, Emacs accesses the file over the network via an appropriate protocol. See Remote Files in The GNU Emacs Manual. This handling is done at a very low level, so you may assume that all the functions described in this chapter accept magic file names as file name arguments, except where noted. See Magic File Names, for details.

When file I/O functions signal Lisp errors, they usually use the condition file-error (see Handling Errors). The error message is in most cases obtained from the operating system, according to locale system-messages-locale, and decoded using coding system locale-coding-system (see Locales).

• Visiting Files		Reading files into Emacs buffers for editing.
• Saving Buffers		Writing changed buffers back into files.
• Reading from Files		Reading files into buffers without visiting.
• Writing to Files		Writing new files from parts of buffers.
• File Locks		Locking and unlocking files, to prevent simultaneous editing by two people.
• Information about Files		Testing existence, accessibility, size of files.
• Changing Files		Renaming files, changing permissions, etc.
• Files and Storage		Surviving power and media failures
• File Names		Decomposing and expanding file names.
• Contents of Directories		Getting a list of the files in a directory.
• Create/Delete Dirs		Creating and Deleting Directories.
• Magic File Names		Special handling for certain file names.
• Format Conversion		Conversion to and from various file formats.