/usr/lib/R/site-library/getopt/help/AnIndex is in r-cran-getopt 1.20.0-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | getopt-package getopt
getopt getopt
get_Rscript_filename get_Rscript_filename
sort_list sort_list
|