Linking postgresql in homebrew - postgresql

Question

I already installed postgresql, but it says I did not link to it.
I am running this in the command line and getting the following error:
myname#MacBook-Pro-8 ~> brew install postgresql
Warning: postgresql 10.4 is already installed, it's just not linked
You can use `brew link postgresql` to link this version.
myname#MacBook-Pro-8 ~> brew link postgresql
Linking /usr/local/Cellar/postgresql/10.4...
Error: Could not symlink share/man/man7/ABORT.7
/usr/local/share/man/man7 is not writable.
myname#MacBook-Pro-8 ~> sudo brew link postgresql
Password:
Error: Running Homebrew as root is extremely dangerous and no longer supported.
As Homebrew does not drop privileges on installation you would be giving all build scripts full access to your system.
I also tried:
brew prune; brew link postgresql
which gave me the same error:
Error: Could not symlink share/man/man7/ABORT.7
/usr/local/share/man/man7 is not writable.
Why is that folder not writable and what can I do to change that?

Answer 1

It was really painful solving this problem, so I figured I would leave it here for others to see.
Issue:
Homebrew install of Postgresql will not execute successfully. $ brew link postgresql results in failure due to directory not writable. New version of Homebrew will not allow sudo commands and System Integrity Protection prevents changing permissions.
Details:
I tried to use homebrew to install postgres and kept running into issues with syslink. When I ran $ brew link postgresql as homebrew suggested, I kept running into an error that it couldn't be completed because certain folders were not writable. I thought this would be easily remedied by running sudo but unfortunately the most current version of homebrew no longer allows the use of sudo commands due to security risks. My next thought was to my root user and use the macOS GUI interface to change the permissions on this folder because I am not sure how to do this on the terminal. Regardless of being logged in as 'root,' the OS would not let me change the permissions of the folder. I also attempted to use sudo and change the permissions in terminal and it did not work either. After several days of banging my head against the wall try all kinds of things to find a solution, I discovered that since El Capitan, macOS introduced System Integrity Protection aka 'SIP' or 'rootless.' As it turned out, once I disabled SIP, logged back into 'root' and changed my regular accounts permissions to Read/Write on the problem directories, I was able to go back to my regular account and successfully execute $ brew install postgresql.
(Assuming you currently have postgresql installed through homebrew but unable to link due a scenario like the one mentioned above, here is what I suggest to resolve your issue...)
Run $ brew link postgresql
Write down the directory path that the error says it is not able to write to. (e.g. usr/local/share/man/man7) NOTE: you'll want to actually write this down on paper or take a picture of the screen on your phone because you will not be able to use copy and paste)
Enable your 'root' user account if you have not already done so.
(instructions here) NOTE: make sure to make a really good password for this account and write it down somewhere safe. This is a powerful account and there's no way to recover the password.
Disable System Integrity Protection.
(instructions here)
Log into 'root' user account
In Finder menu bar select GO > GO TO FOLDER... (CMND + SHFT + G) and type in the path from Step 2.
Right-Click/ Cntrl-Click the folder and select Get Info
Click the plus sign at the bottom of Sharing & Permissions
Add your regular account to the list and change the permission to Read & Write
Go back to your regular account, run $ brew uninstall postgresql, then $ brew update and $ brew doctor . If those are all set run $ brew install postgresql.
You should be able to install without any problems now. However, if you run into a linking and permissions problem again, run $ brew link postgresql to figure out the problematic directory and repeat Steps 5 - 10 with whatever other directories are giving you trouble.
If everything is up and running properly. It is probably best to at least enable SIP again (instruction in the article linked in Step 4).
(To check that everything is working. I recommend running $ brew services start postgresql then $ createdb 'test' . In my case, it was when I originally tried to run createdb and got "command not found" that I realized something was wrong.)

Answer 2

Running this solves it. This gets around SIP.
sudo chown -R $(whoami) $(brew --prefix)/*
brew link postgresql