The bell command rings the terminal bell. The bell is associated with the display; even if you are executing your program on a remote machine, the bell is heard by the user. If your application has windows on multiple displays, you can direct the bell to the display of a particular window with the -displayof option. The syntax for the bell command is given below:
bell ?-displayof window?
UNIX has an xset program that controls the bell's duration, pitch, and volume. The volume is in percent of a maximum, for example, 50. In practice, many keyboard bells only support a variable duration; the pitch and volume are fixed. The arguments of xset that control the bell are shown below.
exec xset b ?volume? ?hertz? ?milliseconds?