#### 25.2.17 ed [Function] ¶

`ed` &optional x ⇒ implementation-dependent

#### Arguments and Values:: ¶

x—nil, a pathname, a string, or a function name.

The default is nil.

#### Description:: ¶

ed invokes the editor if the implementation provides a resident editor.

If x is nil, the editor is entered. If the editor had been previously entered, its prior state is resumed, if possible.

If x is a pathname or string, it is taken as the pathname designator for a file to be edited.

If x is a function name, the text of its definition is edited. The means by which the function text is obtained is implementation-defined.

#### Exceptional Situations:: ¶

The consequences are undefined if the implementation does not provide a resident editor.

Might signal type-error if its argument is supplied but is not a symbol, a pathname, or nil.

If a failure occurs when performing some operation on the file system while attempting to edit a file, an error of type file-error is signaled.

An error of type file-error might be signaled if x is a designator for a wild pathname.

Implementation-dependent additional conditions might be signaled as well.

#### See Also:: ¶

pathname,

logical-pathname,

compile-file [Function] , load [Function] ,

Pathnames as Filenames