New to Homebrew and Terminal, need help....

[BadRobot-cooked]

I have a MacMini 2018 and wanted to install SmartMonTools. (I already installed in on MBA M1 to see SSD data)
I thought I had installed Brew already, but not SmartMonTools. So went ahead and entered "brew install smartmontools"
Some activity went by, then an error message...

The brew link step did not complete successfully
The formula built, but is not symlinked into /usr/local
Could not symlink share/doc/smartmontools/AUTHORS
Target /usr/local/share/doc/smartmontools/AUTHORS
already exists. You may want to remove it:
rm '/usr/local/share/doc/smartmontools/AUTHORS'

So I thought this meant smartmoxntools was already present. But entering command "smartctl -a disk0 " gets the reply smartctl not found.

I then thought, OK uninstall brew....brew uninstall
Which gives this message, after a bit of text activity

Error: Invalid usage: This command requires at least 1 installed formula or installed cask argument.

I have no idea what to do next, not a terminal expert!

[carlocab]

Try brew link --overwrite smartmontools. As the flag suggests, it'll overwrite anything it conflicts with in /usr/local. If you want to see what'll be overwritten before actually doing it, you can do brew link --dry-run smartmontools.

[BadRobot-cooked]

this is what it replies...

Error: Could not symlink share/doc/smartmontools/AUTHORS
/usr/local/share/doc/smartmontools is not writable.

[BadRobot-cooked]

wow, quick reply and thank you! it's a long reply...
total 0
drwxr-xr-x 16 root wheel 512 8 Mar 23:39 .
drwxr-xr-x@ 11 root wheel 352 1 Jan 2020 ..
-rw-r--r--@ 1 root wheel 0 27 Sep 2019 .com.apple.installer.keep
drwxrwxr-x 2 macmini admin 64 12 Sep 2019 Caskroom
drwxrwxr-x 70 macmini admin 2240 8 Mar 19:02 Cellar
drwxrwxr-x 4 macmini admin 128 7 May 2020 Frameworks
drwxrwxr-x 21 macmini admin 672 8 Mar 19:13 Homebrew
drwxrwxr-x 243 macmini admin 7776 11 Mar 16:50 bin
drwxrwxr-x 12 macmini admin 384 9 Mar 15:41 etc
drwxrwxr-x 116 macmini admin 3712 7 May 2020 include
drwxrwxr-x@ 457 root admin 14624 7 May 2020 lib
drwxrwxr-x 79 macmini admin 2528 11 Mar 16:50 opt
drwxr-xr-x@ 3 root wheel 96 12 Apr 2019 remotedesktop
drwxrwxr-x 13 macmini admin 416 9 Mar 15:39 sbin
drwxrwxr-x 25 macmini admin 800 7 May 2020 share
drwxrwxr-x 6 macmini admin 192 8 Mar 19:02 var
total 0
drwxrwxr-x 25 macmini admin 800 7 May 2020 .
drwxr-xr-x 16 root wheel 512 8 Mar 23:39 ..
-rw-r--r-- 1 macmini admin 0 7 May 2020 .keepme
drwxr-xr-x 23 macmini admin 736 7 May 2020 aclocal
lrwxr-xr-x 1 macmini admin 43 12 Sep 2019 bash-completion -> ../Cellar/glib/2.62.0/share/bash-completion
drwxr-xr-x 28 macmini admin 896 7 May 2020 doc
lrwxr-xr-x 1 macmini admin 37 12 Sep 2019 ffmpeg -> ../Cellar/ffmpeg/4.1.4_2/share/ffmpeg
drwxr-xr-x 3 macmini admin 96 12 Sep 2019 fish
lrwxr-xr-x 1 macmini admin 44 12 Sep 2019 fontconfig -> ../Cellar/fontconfig/2.13.1/share/fontconfig
lrwxr-xr-x 1 macmini admin 31 12 Sep 2019 gdb -> ../Cellar/glib/2.62.0/share/gdb
drwxr-xr-x 12 macmini admin 384 7 May 2020 gettext
lrwxr-xr-x 1 macmini admin 47 7 May 2020 gettext-0.20.2 -> ../Cellar/gettext/0.20.2_1/share/gettext-0.20.2
lrwxr-xr-x 1 macmini admin 38 12 Sep 2019 gir-1.0 -> ../Cellar/harfbuzz/2.6.1/share/gir-1.0
lrwxr-xr-x 1 macmini admin 36 12 Sep 2019 glib-2.0 -> ../Cellar/glib/2.62.0/share/glib-2.0
lrwxr-xr-x 1 macmini admin 42 12 Sep 2019 graphite2 -> ../Cellar/graphite2/1.3.13/share/graphite2
drwxr-xr-x 3 macmini admin 96 12 Sep 2019 gtk-doc
drwxr-xr-x 32 macmini admin 1024 7 May 2020 info
drwxr-xr-x 4 macmini admin 128 12 Sep 2019 java
drwxr-xr-x 104 macmini admin 3328 7 May 2020 locale
drwxr-xr-x 7 macmini admin 224 29 Jan 2020 man
lrwxr-xr-x 1 macmini admin 34 7 May 2020 misc -> ../Cellar/libmagic/5.38/share/misc
drwxr-xr-x 3 root admin 96 9 Mar 15:39 smartmontools
lrwxr-xr-x 1 macmini admin 40 12 Sep 2019 tessdata -> ../Cellar/tesseract/4.1.0/share/tessdata
lrwxr-xr-x 1 macmini admin 37 12 Sep 2019 xml -> ../Cellar/fontconfig/2.13.1/share/xml
drwxr-xr-x 3 macmini admin 96 12 Sep 2019 zsh

[carlocab]

This looks like your problem:

drwxr-xr-x 3 root admin 96 9 Mar 15:39 smartmontools

It's owned by root. Compare this to all the other entries, which indicate they are owned by macmini (I'm assuming you get macmini as the output of whoami.)

I'm guessing you've installed smartmontools outside of Homebrew before. To fix this, just remove the offending smartmontools directory with

sudo rm -rf /usr/local/share/doc/smartmontools

The sudo command will ask for your password. Once you've done that, try

brew reinstall smartmontools

[BadRobot-cooked]

there is still an error message in amongst the reply, so not sure if smartmontools is actually re-installed...
==> Downloading https://homebrew.bintray.com/bottles/smartmontools-7.2.big_sur.b
Already downloaded: /Users/macmini/Library/Caches/Homebrew/downloads/2a4e1036f7ac31b5abc450600b8bab6db0ef1d43618e96013cf18cba7f4b838c--smartmontools-7.2.big_sur.bottle.tar.gz
==> Reinstalling smartmontools
==> Pouring smartmontools-7.2.big_sur.bottle.tar.gz
Error: The brew link step did not complete successfully
The formula built, but is not symlinked into /usr/local
Could not symlink share/man/man5/smartd.conf.5
Target /usr/local/share/man/man5/smartd.conf.5
already exists. You may want to remove it:
rm '/usr/local/share/man/man5/smartd.conf.5'

To force the link and overwrite all conflicting files:
brew link --overwrite smartmontools

To list all files that would be deleted:
brew link --overwrite --dry-run smartmontools

Possible conflicting files are:
/usr/local/share/man/man5/smartd.conf.5
/usr/local/share/man/man8/smartctl.8
/usr/local/share/man/man8/smartd.8
/usr/local/share/man/man8/update-smart-drivedb.8
/usr/local/share/smartmontools/drivedb.h
==> Summary
🍺 /usr/local/Cellar/smartmontools/7.2: 36 files, 1.9MB

[carlocab]

You'll need to remove the rest of the conflicting files. Do

sudo rm -rf /usr/local/share/man/man5/smartd.conf.5
sudo rm -rf /usr/local/share/man/man8/smartctl.8
sudo rm -rf /usr/local/share/man/man8/smartd.8
sudo rm -rf /usr/local/share/man/man8/update-smart-drivedb.8
sudo rm -rf /usr/local/share/smartmontools/drivedb.h
brew reinstall smartmontools

[BadRobot-cooked]

genius! now it works and thank you I'd never have done that myself.