25 Files

In Emacs, you can find, create, view, save, and otherwise work with files and file directories. This chapter describes most of the file-related functions of Emacs Lisp, but a few others 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 actually a string. Most of these functions expand file name arguments by calling expand-file-name, so that ~ is handled correctly, as are relative file names (including ‘../’). These functions don't recognize environment variable substitutions such as ‘$HOME’. See File Name Expansion.

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-message-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 protection, etc.
• 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: Defining "magic" special handling for certain file names.
• Format Conversion: Conversion to and from various file formats.