warning: Insecure world writable dir /usr/local/bin in PATH, mode 040777

Question

You will need to have root access to do this. If you aren't already the administrative user, login as the administrator. Then use 'sudo' to change the permissions:

sudo chmod go-w /usr/local/bin

Obviously, that will mean you can no longer install material in /usr/local/bin except via 'sudo', but you probably shouldn't be doing that anyway.

I had the same error here MacOSX 10.6.8 - it seems ruby checks to see if any directory (including the parents) in the path are world writable. In my case there wasn't a /usr/local/bin present as nothing had created it.

so I had to do

sudo chmod 775 /usr/local

to get rid of the warning.

A question here is does any non root:wheel process in MacOS need to create anything in /usr/local ?

Try: sudo chmod go-w /usr/local/bin

The /usr/local/bin directory is owned by the root (i.e. administrator) account, so even if you can write to it, you can't change the permissions on it. The sudo command means "run the following command as root", and works a lot like clicking that lock icon in the System Preferences dialogs.

I have had the same issue in OSX. It can be fixed by running Disk Utilities to Repair Permissions. I agree with Peter Nixey: in my case it is caused when my 3G dongle installs or reinstalls its driver. Repairing Permissions afterward fixes the issue.

Am using Mountain Lion. What I did was Look for /usr/local and Get Info. On it there is Sharing and Permissions. Make sure that its only the user and Admin are the only ones who have read and write permissions. Anyone else should have read access only. That sorted my problem.

Its normally helpful is your Run disk utilities and repair permissions too.

Same here, apparently my /usr/local folder was world writable so I made it 755

# chmod 755 /usr/local

It also appeared that a Hauwei mobile dongle I had used had installed world writeable directories in /usr/local as well

If you're running OSX and getting this often, another good thing to consider is to use a built-in OSX permissions fixing tool. If you didn't change the mode of your directories, something else did and there's a chance that other directories have overgenerous permissions as well - this tool will reset them back all to factory defaults, which is a good security idea. There's a great guide on the Apple stackextange about this very process.