/usr/share/plplot5.10.0/tcl/cmap1d.pal is in plplot-tcl 5.10.0-0ubuntu5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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#000fb2 00 0
#4a47ff 23 0
#573357 40 1
#a46823 44 0
#e6bf00 65 0
#b80000 100 0
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