Variable: message-truncate-lines
message-truncate-lines is a variable defined in xdisp.c.
Value
nil
Documentation
If non-nil, messages are truncated when displaying the echo area.
Bind this around calls to message to let it take effect.
Probably introduced at or before Emacs version 21.1.
Source Code
// Defined in /usr/src/emacs/src/xdisp.c
DEFVAR_BOOL ("message-truncate-lines", message_truncate_lines,
doc: /* If non-nil, messages are truncated when displaying the echo area.
Bind this around calls to `message' to let it take effect. */);