/usr/share/plplot5.9.9/cmap1_blue_yellow.pal is in libplplot11 5.9.9-2ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 | v2 rgb
7
0.0 1.0 1.0 1.0 1.0 0
0.001 0.001 0.998 1.0 1.0 0
0.25 0.25 0.50 1.0 1.0 0
0.5 0.5 0.5 0.5 1.0 0
0.75 1.0 0.5 0.25 1.0 0
0.999 1.0 0.998 0.001 1.0 0
1.0 0.0 0.0 0.0 1.0 0
|