$ xsel --help
Usage: xsel [options]Manipulate the X selection.
By default the current selection is output and not modified if both
standard input and standard output are terminals (ttys). Otherwise,
the current selection is output if standard output is not a terminal
(tty), and the selection is set from standard input if standard input
is not a terminal (tty). If any input or output options are given thenthe program behaves only in the requested mode.
If both input and output is required then the previous selection is
output before being replaced by the contents of standard input.
-a, --append Append standard input to the selection
-f, --follow Append to selection as standard input grows
-i, --input Read standard input into the selection
-o, --output Write the selection to standard output
-c, --clear Clear the selection
-d, --delete Request that the selection be cleared and that
the application owning it delete its contents
-p, --primary Operate on the PRIMARY selection (default) -s, --secondary Operate on the SECONDARY selection
-b, --clipboard Operate on the CLIPBOARD selection
-k, --keep Do not modify the selections, but make the PRIMARY
and SECONDARY selections persist even after the
programs they were selected in exit.
-x, --exchange Exchange the PRIMARY and SECONDARY selections
Specify the connection to the X server
-t ms, --selectionTimeout ms
Specify the timeout in milliseconds within which the
selection must be retrieved. A value of 0(zero) specifies no timeout (default)Miscellaneous options
-l, --logfile Specify file to log errors to when detached.
-n, --nodetach Do not detach from the controlling terminal. Without
this option, xsel will fork to become a background
process in input, exchange and keep modes.
-h, --help Display this help and exit -v, --verbose Print informative messages
--version Output version information and exitPlease report bugs to <firstname.lastname@example.org>.