How to tell if homebrew is installed on Mac OS X - ruby-on-rails

Question

I am doing some Rails programming and I consistently see Homebrew referenced in solutions around the web but have never used it.
I also notice Homebrew in the terminal version 2.9 as an option next to "Shell -> New" from the terminal drop down but when I select homebrew and issue commands, they fail.
Usually with the "command not found" error.
Strangely enough I have been unable to locate a simple command to determine whether brew is installed or not.
How do I check to see if Homebrew is already installed on my Mac?

Answer 1

brew help. If brew is there, you get output. If not, you get 'command not found'. If you need to check in a script, you can work out how to redirect output and check $?.

Answer 2

I use this to perform update or install:
which -s brew
if [[ $? != 0 ]] ; then
# Install Homebrew
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
else
brew update
fi

Answer 3

The standard way of figuring out if something is installed is to use which.
If Brew is installed.
>>> which brew
/usr/local/bin/brew
If Brew is not installed.
>>> which brew
brew not found
Note: The "not installed" message depends on your shell. zsh is shown above. bash will just not print anything. csh will say brew: Command not found. In the "installed" case, all shells will print the path.)
It works with all command line programs. Try which grep or which python. Since it tells you the program that you're running, it's helpful when debugging as well.

Answer 4

While which is the most common way of checking if a program is installed, it will tell you a program is installed ONLY if it's in the $PATH. So if your program is installed, but the $PATH wasn't updated for whatever reason*, which will tell you the program isn't installed.
(*One example scenario is changing from Bash to Zshell and ~/.zshrc not having the old $PATH from ~/.bash_profile)
command -v foo is a better alternative to which foo. command -v brew will output nothing if Homebrew is not installed
command -v brew
Here's a sample script to check if Homebrew is installed, install it if it isn't, update if it is.
if [[ $(command -v brew) == "" ]]; then
echo "Installing Hombrew"
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
else
echo "Updating Homebrew"
brew update
fi

Answer 5

brew -v or brew --version does the trick!

Answer 6

I just type brew -v in terminal if you have it it will respond with the version number installed.

Answer 7

Location of the brew where it installed
which brew
version of home brew install
brew --version

Answer 8

[ ! -f "`which brew`" ] && echo "not installed"
Explaination: If brew is not installed run command after &&

Answer 9

brew doctor checks if Homebrew is installed and working properly.

Answer 10

use either the which or type built-in tools.
i.e.: which brew or type brew

Answer 11

Maybe your mac don't received the path
enter image description here
Run command below
eval "$(/opt/homebrew/bin/brew shellenv)"
And run to check that work
brew help

Answer 12

Beginners normally do, the homebrew --version which is wrong.
Do instead, brew --version. brew help works also. If these two commands are not executed, you don't have homebrew installed.

Answer 13

Another one possible way:
# Check if Ninja is installed
if ! which ninja > /dev/null
then
echo 'Ninja installation...'
brew install ninja
fi

Answer 14

In my case Mac OS High Sierra 10.13.6
brew -v
OutPut-
Homebrew 2.2.2
Homebrew/homebrew-core (git revision 71aa; last commit 2020-01-07)
Homebrew/homebrew-cask (git revision 84f00; last commit 2020-01-07)

Answer 15

Yes you can run which brew, but you may have it installed and it says it is not found if you are using zsh. You will need to add it to your .zshrc file.

Answer 16

I find it simple to use brew help command to find it is installed or not. There was a user guide on the homebrew download page.
If it is not installed then it will show 'command not found'
If you need to install homebrew then paste this on terminal:
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

Answer 17

jest write brew -v in terminal and if you have it , you will see there version number and the install date .
like this :
Homebrew 3.3.12
Homebrew/homebrew-core (git revision c3cacc9cd1d; last commit 2022-01-31)
Homebrew/homebrew-cask (git revision fb6ec06d8b; last commit 2022-01-31)

Answer 18

Once you install Homebrew, type command brew doctor in terminal.
If you get the following message:
Your system is ready to brew
then you are good to go and you have successfully installed homebrew.
If you get any warnings, you can try fixing it.

Answer 19

Another way to do it is using the "command" builtin tool
if [ "$(command -v brew)" ]; then
echo "command \"brew\" exists on system"
fi

Answer 20

in your terminal, do which brew and itll tell you where it was installed at within your computer, but itll only work in zsh not in bash.

Answer 21

Running Catalina 10.15.4 I ran the permissions command below to get brew to install
sudo chown -R $(whoami):admin /usr/local/* && sudo chmod -R g+rwx /usr/local/*