How do I remove "permission denied" printout statements from the find program?

Question

Code

find / -name netcdf

Output

find: `/root/.dbus': Permission denied
find: `/root/.gconf': Permission denied
find: `/root/.gconfd': Permission denied
find: `/root/.gnome': Permission denied
find: `/root/.gnome2': Permission denied
find: `/root/.gnome2_private': Permission denied

Answer 1

Those messages are sent to stderr, and pretty much only those messages are generally seen on that output stream. You can close it or redirect it on the command-line.

$ find / -name netcdf 2>&-

or

$ find / -name netcdf 2>/dev/null

Also, if you are going to search the root directory (/), then it is often good to nice the process so find doesn't consume all the resources.

$ nice find / -name netcdf 2>&-

This decreases the priority of the process allowing other processes more time on the CPU. Of course if nothing else is using the CPU, it doesn't do anything. :) To be technical, the NI value (seen from ps -l) increase the PRI value. Lower PRI values have a higher priority. Compare ps -l with nice ps -l.

Answer 2

I would just like point out this answer by @Gilles in Exclude paths that make find complain about permissions - Unix & Linux Stack Exchange; it basically involves a construct for find that makes it not descend unreadable directories, and in that sense, is probably also a bit faster.

This would seem to work for me:

With GNU find or any other find that supports the -readable and -executable predicates:

find / -type d ! \( -readable -executable \) -prune -o -type f -name netcdf -print

or also this:

find / -type d ! -perm -g+r,u+r,o+r -prune -o -type f -name 'netcdf' -print

For some reason, I need to add all of the g+r,u+r,o+r (shortcut for that is a+r), otherwise if one of them is left out, I may still get "Permission Denied" hits.

Here is a breakdown of how I see this (note the -a (and) operator in find is implicit between two predicates):

find /         # find starting from path /
  -type d        # match type is directory
  ! -perm -a+r   # (and) match not permissions of `r`ead present 
  -prune         # ignore what matched above and do not descend into it
  -o             # or (whatever didn't match above)
  -type f        # match type is file
  -name 'netcdf' # (and) match name is 'netcdf'
  -print         # print what matched above

Note that without the last -print, I get some extra items shown (that have nothing to do with -name 'netcdf'); the -print ensures that only the name matches are printed (if any).

Answer 3

Use locate(1) instead:

$ locate netcdf

It will only show you files your user can see.