Change PHP version on MacOS

php.sh

#!/bin/bash

available=$(brew list --formula -1 | egrep '^php@|^php$')

syntax () {
	echo "SYNTAX: $0 <version>"
	echo ""
	echo -n "<version> needs to be one of: "
	echo $available
	echo ""
	echo "Choose the latest version of PHP by naming 'php' as the version"
	exit 2
}

# check if enough arguments
if [ "$#" -ne 1 ]; then
	syntax
fi

version=$(echo "${available}" | grep "${1}" | head -n 1)

# check if valid version
if [[ -z "$version" ]]; then
	syntax
fi

# do it
echo "Will use version $version"
echo $available | xargs brew unlink

# first default to a known 'safe' version, 
# otherwise we cannot always do the change
brew link php@7.4
valet use php@7.4 --force

# now change to the requested version
valet use "$version" --force

The change to PHP7.4 is unfortunately necessary because you cannot otherwise safely change between PHP 5.x and other versions of PHP.

Note that this script uses valet as well. If you don't use that, simply delete these two lines.

Updated script for users who don't use valet (or rather, it's not in search PATH).
It's not enough to simply comment out the two valet lines, since that will always end up linked to php@7.4

Also checks that you are not actually requesting php@7.4, which would generate an 'already linked' warning

#!/bin/bash

available=$(brew list --formula -1 | egrep '^php@|^php$')

syntax () {
        echo "SYNTAX: $0 <version>"
        echo ""
        echo -n "<version> needs to be one of: "
        echo $available
        echo ""
        echo "Choose the latest version of PHP by naming 'php' as the version"
        exit 2
}

# check if enough arguments
if [ "$#" -ne 1 ]; then
        syntax
fi

version=$(echo "${available}" | grep "${1}" | head -n 1)

# check if valid version
if [[ -z "$version" ]]; then
        syntax
fi

# do it
echo "Will use version $version"
echo $available | xargs brew unlink

# first default to a known 'safe' version,
# otherwise we cannot always do the change
brew link php@7.4

valet_bin=`which valet`
if [ -z "${valet_bin}" ]; then
  if [ "${version}" != "php@7.4" ]; then
    brew link "${version}"
  fi;
  exit
fi;

valet use php@7.4 --force

# now change to the requested version
valet use "$version" --force

@infostreams Thanks, this was really useful for me as I also use Laravel Valet. To run the script I did the following:

1. $ chmod +x php.sh
2. $ ./php.sh php@7.4
3. Enter sudo password

Notice having to use the @ symbol to install a PHP version as it didn't work first time around.