$ emacs-nightly --batch --eval "(progn
> (describe-function 'append)
> (other-window 1)
> (princ (buffer-substring-no-properties (line-beginning-position 3) (point-max))))" 2> /dev/null
append is a built-in function in ‘C source code’.
(append &rest SEQUENCES)
Concatenate all the arguments and make the result a list.
The result is a list whose elements are the elements of all the arguments.
Each argument may be a list, vector or string.
The last argument is not copied, just used as the tail of the new list.
可以提供更多信息,例如, 是否 Interactive 函数,是 C 函数还是 Elisp 函数,函数自那个版本开始存在,不同 Emacs 版本之间的差异:
Emacs 25
$ curl http://~/25/string-to-unibyte
string-to-unibyte is a built-in function in ‘C source code’.
(string-to-unibyte STRING)
Return a unibyte string with the same individual chars as STRING.
If STRING is unibyte, the result is STRING itself.
Otherwise it is a newly created string, with no text properties,
where each ‘eight-bit’ character is converted to the corresponding byte.
If STRING contains a non-ASCII, non-‘eight-bit’ character,
an error is signaled.
Emacs 27
$ curl http://~/27/string-to-unibyte
string-to-unibyte is a built-in function in ‘C source code’.
(string-to-unibyte STRING)
This function is obsolete since 26.1;
use `encode-coding-string'.
Return a unibyte string with the same individual chars as STRING.
If STRING is unibyte, the result is STRING itself.
Otherwise it is a newly created string, with no text properties,
where each ‘eight-bit’ character is converted to the corresponding byte.
If STRING contains a non-ASCII, non-‘eight-bit’ character,
an error is signaled.