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18 File Handling

The operating system stores data permanently in named files, so most of the text you edit with Emacs comes from a file and is ultimately stored in a file.

To edit a file, you must tell Emacs to read the file and prepare a buffer containing a copy of the file’s text. This is called visiting the file. Editing commands apply directly to text in the buffer; that is, to the copy inside Emacs. Your changes appear in the file itself only when you save the buffer back into the file.

In addition to visiting and saving files, Emacs can delete, copy, rename, and append to files, keep multiple versions of them, and operate on file directories.

File Names  How to type and edit file-name arguments.
Visiting  Visiting a file prepares Emacs to edit the file.
Saving  Saving makes your changes permanent.
Reverting  Reverting cancels all the changes not saved.
Auto Revert  Keeping buffers automatically up-to-date.
Auto Save  Auto Save periodically protects against loss of data.
File Aliases  Handling multiple names for one file.
Directories  Creating, deleting, and listing file directories.
Comparing Files  Finding where two files differ.
Diff Mode  Mode for editing file differences.
Copying and Naming  Copying, naming and renaming files.
Misc File Ops  Other things you can do on files.
Compressed Files  Accessing compressed files.
File Archives  Operating on tar, zip, jar etc. archive files.
Remote Files  Accessing files on other machines.
Quoted File Names  Quoting special characters in file names.
File Name Cache  Completion against a list of files you often use.
File Conveniences  Convenience features for finding files.
Image Mode  Viewing image files.
Filesets  Handling sets of files.