Parcellite features a clipboard CLI. Unrecognized options and the contents of your standard input get copied to your clipboard. See CLI EXAMPLES.
Look at the tool tips by hovering over each item in the prefrences dialog.
'Ignore Whitespace Only' - If checked, will ignore any clipboard additions that contain only whitespace.
'Trim Whitespace' - If checked, will trim whitespace from beginning and end of entry.
'Trim Newlines' - If checked, will replace newlines with spaces.
Website: http://parcellite.sourceforge.net