1. careful when using `find .` without a `-type` like `f` or `d`, because `l` aka symlinks are implied,
  2. and so if you `-exec chown` or `chmod`, it will change system files outside of current dir because symlinks point to them
  3. to see what system files would be changed:
  4. sudo find . -type l -exec realpath {} \; | sort -u
  5. i had to restore owner and u+w to some 109 files
  6. ------
  7. also, when renaming username (eg. usermod) the temporary breakage of symlinks(eg. .bashrc) will cause bash to trim the bash history eg. from 67k to 1k lines
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