To copy the contents of a file into a buffer, use the function
insert-file-contents. (Don’t use the command
insert-file in a Lisp program, as that sets the mark.)
This function inserts the contents of file filename into the current buffer after point. It returns a list of the absolute file name and the length of the data inserted. An error is signaled if filename is not the name of a file that can be read.
This function checks the file contents against the defined file
formats, and converts the file contents if appropriate and also calls
the functions in the list
See Format Conversion. Normally, one of the functions in the
after-insert-file-functions list determines the coding system
(see Coding Systems) used for decoding the file’s contents,
including end-of-line conversion. However, if the file contains null
bytes, it is by default visited without any code conversions.
If visit is non-
nil, this function additionally marks the
buffer as unmodified and sets up various fields in the buffer so that it
is visiting the file filename: these include the buffer’s visited
file name and its last save file modtime. This feature is used by
find-file-noselect and you probably should not use it yourself.
If beg and end are non-
nil, they should be numbers
that are byte offsets specifying the portion of the file to insert.
In this case, visit must be
nil. For example,
(insert-file-contents filename nil 0 500)
inserts the first 500 characters of a file.
If the argument replace is non-
nil, it means to replace the
contents of the buffer (actually, just the accessible portion) with the
contents of the file. This is better than simply deleting the buffer
contents and inserting the whole file, because (1) it preserves some
marker positions and (2) it puts less data in the undo list.
It is possible to read a special file (such as a FIFO or an I/O device)
insert-file-contents, as long as replace and
This function works like
insert-file-contents except that it
does not run
after-insert-file-functions, and does not do
format decoding, character code conversion, automatic uncompression,
and so on.
If you want to pass a file name to another process so that another
program can read the file, use the function
Magic File Names.