Install Slack app in User's ~/Applications directory - macOS

slack_app_installer_homedir_macOS.md

Install Slack app in User's Applications Directory - macOS

Background

This work was inspired by the challenges I encountered in the workplace. I manage several macOS remotely, and one of the biggest pains is that our users aren't administrators on those machines. Thus, they aren't able to dismiss the Squirrel Update prompts on their own, which was a productivity hindrance.

Initially as a fun side-project to satisfy my curiosity, I came up with a solution to mitigate this by having the Slack app, which was already installed in the main /Applications directory, automatically update itself as soon as the Launch Daemon script fetches a new update from slack.com. The script would notify all users actively using Slack that the app would restart itself in several seconds.

Admittedly, the above solution wasn't organic and understandably it can be a grave security concern for some. The only upside of this solution is that all users on the same machine would be using the same copy of the latest Slack version, which simplifies the deployment.

Solution

Fortunately for us, Slack developed a knowledge-base article on enterprise deployment best practices. Optionally, we can deploy Slack app to each user's ~/Applications directory. By default the directory doesn't exist and has to be created. This would also requires multiple copies of Slack apps on the same machine for multiple non-admin users to access. From an administrative prospective, one would have to be extremely mindful to also query the apps installed in users' home directories as several management tools rarely take ~/Applications directory in consideration.

The new solution script below would help simplify the deployment by installing the Slack app in the users' ~/Applications directory and add the shortcut to Dock. The only caveat is that you must provide a pre-determined list of users for the machine you attempt to run the script against. Not every user on the system would need Slack in their Dock. Also, this script wouldn't run if the installed copy of Slack was originally sourced from the App Store or MDM managed by the IT organization. Those copies of Slack don't have the Squirrel Update prompts.

Quick Start

Update the user list nears line 32. You'd need to list the available users on the system that need Slack app in their home directories. The script must be run by root. At the time of this writing, the script was compatible with Big Sur (macOS 11) and Sierra (macOS 10.12).

chmod +x slack_app_installer_homedir_macOS.sh
sudo slack_app_installer_homedir_macOS.sh

PLEASE NOTE: The system can be left without a working copy of Slack if the app has been removed from /Applications and there is no eligible user to receive the app in their ~/Applications directory.

slack_app_installer_homedir_macOS.sh

#!/usr/bin/env bash

# Attempting to remove the existing system-wide Slack app
if [ -d "/Applications/Slack.app" ]; then

    if [[ $(mdls -name kMDItemAppStoreReceiptIsVPPLicensed /Applications/Slack.app | awk '{ print $NF }') == "(null)" ]]; then
        echo "Direct-download system Slack app was detected. This copy of Slack app will be removed."

        # Kill Slack app if still running
        if [ ! -z "$(pgrep '[Ss]lack')" ]; then
            echo "Slack was running. Closing Slack..."
            killall -SIGKILL "Slack"
        fi

        # Removing Slack app
        echo "Deleting Slack app..."
        rm -rf /Applications/Slack.app
    else
        echo "The installed copy of Slack app either has a valid VPP license or is purchased through the App Store. The script will now exit."
        exit 1
    fi
else
    # Proceed to attempt installing Slack in user's ~/Applications directory
    echo "Slack app wasn't installed in /Applications. The script will now attempt to install Slack in user(s)' ~/Applications."
fi


##################################################################################
# PLEASE UPDATE THE USER LIST HERE IF NECESSARY. THEY MUST BE SEPARATED BY SPACE #
##################################################################################
# List of users
listed_users="bashtheshell travis.johnson testuser"


# Slack download variables
slackDownloadUrl=$(curl "https://slack.com/ssb/download-osx" -s -L -I -o /dev/null -w '%{url_effective}')
dmgName=$(printf "%s" "${slackDownloadUrl[@]}" | sed 's@.*/@@')
slackDmgPath="/private/tmp/$dmgName"


# Check if there exists a listed user without Slack app in their ~/Applications directory before proceeding to download Slack
set -- $listed_users
no_user="true"
while [ $# -gt 0 ]; do

    # Check if user's home directory actually exist before attempting to download Slack
    if [ ! -d "/Users/${1}/" ]; then
        # Skip to next user if user's home directory is non-existent
        shift
    else
        # Download Slack for user(s) with missing Slack app
        if [ ! -d "/Users/${1}/Applications/Slack.app" ]; then

            no_user="false"   # Set to false as there exists a user

            # Detach Slack DMG volume if already mounted
            if [ ! -z "$(ls -d /Volumes/Slack* 2>/dev/null)" ]; then
                echo 'Ejecting all the DMG volumes...'
                for disk in $(hdiutil info | grep /dev/disk | grep partition | cut -f 1); do
                    hdiutil detach ${disk}
                done
            fi


            # Downloads latest version of Slack or else exit script if download fails
            echo "Downloading latest Slack app (${dmgName})..."
            curl -L -o "$slackDmgPath" "$slackDownloadUrl"
            if [ $? -ne 0 ]; then
                echo "ERROR: Unable to download Slack. System may be offline. This script will now exit."
                exit 10
            fi


            # Mounts the DMG volume
            echo 'Mounting the DMG volume...'
            hdiutil attach -nobrowse $slackDmgPath

            break
        fi
        shift
    fi
done


# Print if no eligible user is available
if [[ "$no_user" == "true" ]]; then
    echo "There is no eligible user account with missing Slack app. The script will not install..."
fi


# Install Slack for user(s) without Slack app in their ~/Applications directory 
set -- $listed_users
while [ $# -gt 0 ]; do

    # Check if user's home directory actually exist before creating ~/Applications path
    if [ ! -d "/Users/${1}/" ]; then
        # Skip to next user if user's home directory is non-existent
        shift
    else
        # Remove 'Slack' app from the user's Dock
        echo "Attempting to remove Slack app from ${1}'s Dock..."
        cat << 'EOF' > /tmp/remove_app_from_dock.sh
        #!/usr/bin/env bash
        listOfAppsToRemove=("Slack")
        for i in "${listOfAppsToRemove[@]}"
        do
            appFileLabel=$i # Name of the app as shown in the Dock
            lengthOfPlistArray=$(defaults read com.apple.dock persistent-apps | grep "file-label" | wc -l | tr -d " ") # Get length of array
            appPosition=$lengthOfPlistArray # The position as shown in dock (count starts after 'Finder'). Starting with an invalid index intentionally to prevent accidental deletion.
            numOfPersistApps=$(( $lengthOfPlistArray - 1 )) # Since counting starts at zero
            # Find the position that matches the app name
            for i in $(seq 0 $numOfPersistApps)
            do
                if [[ $(/usr/libexec/PlistBuddy -c "Print persistent-apps:${i}:tile-data:file-label" ~/Library/Preferences/com.apple.dock.plist) == $appFileLabel ]]
                then
                    appPosition=$i
                fi
            done
            # Exit if app is not found in Dock
            if [[ $appPosition -eq $lengthOfPlistArray ]]
            then
                echo "The \"${appFileLabel}\" app is not found in dock. Moving on..."
                continue
            fi
            # Remove this entry from Dock's plist file : com.apple.dock.plist
            /usr/libexec/PlistBuddy -c "Delete persistent-apps:$appPosition" ~/Library/Preferences/com.apple.dock.plist
            # Print to STDOUT if command's successful
            if [[ $? -eq 0 ]]
            then
                echo "The \"${appFileLabel}\" app has been removed. Restarting Dock..."
            fi
            # Restart Dock to persist changes
            killall Dock
        done
EOF
        chmod +x /tmp/remove_app_from_dock.sh
        su - $1 -c '/tmp/remove_app_from_dock.sh'
        rm /tmp/remove_app_from_dock.sh


        # Install Slack for user(s) with missing Slack app
        if [ ! -d "/Users/${1}/Applications/Slack.app" ]; then
            echo "Installing Slack app for ${1}..."
            mkdir -p /Users/${1}/Applications
            ditto -rsrc /Volumes/Slack*/Slack.app /Users/${1}/Applications/Slack.app
            chown -R $1: /Users/${1}/Applications
        fi


        # Add Slack app to Dock in user's profile if not added already
        account_user=$1
        if [[ -z $(su - $account_user -c 'defaults read com.apple.dock persistent-apps | grep "Slack.app"') ]]
        then
            sleep 2     # OS doesn't update the Dock information fast enough at each iteration
            echo "Adding Slack app to $account_user's Dock..."
            su - $account_user -c "defaults write com.apple.dock persistent-apps -array-add '<dict><key>tile-data</key><dict><key>file-data</key><dict><key>_CFURLString</key><string>/Users/'"$account_user"'/Applications/Slack.app</string><key>_CFURLStringType</key><integer>0</integer></dict></dict></dict>'"
            if [[ ! -z "$(sudo -u $account_user SHELL=/bin/bash -i sh -c 'pgrep -U $(id -u) [dD]ock')" ]]; then
                su - $account_user -c 'killall Dock'
            fi
        fi

        shift
    fi
done


# Unmount and eject the DMG volume
echo 'Attempting to eject the DMG volumes if any...'
hdiutil detach /Volumes/Slack.app


# Clean up the downloaded files in /tmp directory
echo 'Cleaning up temporary files if any...'
rm -rf "$slackDmgPath"