how to update homebrew with Cron on Mac os

Cron doesn't have your PATH defined, make sure you always call commands with the full path, which is probably /usr/local/bin/brew update

This is considered good practice to keep unwanted/unexpected commands from running. If someone put a malicious script called 'brew' somewhere else in your path, but before /usr/local/bin, it would get called instead.

A cronjob is a good option, but I didn't want it to happen automatically. I found a script that will notify you if a new version of a formula installed on your Mac is available.

I extended the script to not show pinned formulae in the notifier.

I decided to use a launchd-agent for the cronjb, because this also runs if Mac is started later. Cron-jobs just run if your mac is already on at that time.

For a comparison of cronjob vs launchd, I recommend reading this.

Here's my configuration which runs every day at 10am and 3pm. The script, called by the agent, is located at /usr/local/bin/homebrew-update-notifier.

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"><plist version="1.0"><dict>    <key>EnableGlobbing</key>    <false/>    <key>Label</key>    <string>homebrew.simonsimcity.update-notifier</string>    <key>ProgramArguments</key>    <array>        <string>/bin/bash</string>        <string>/usr/local/bin/homebrew-update-notifier</string>    </array>    <key>RunAtLoad</key>    <true/>    <key>StandardErrorPath</key>    <string>/tmp/homebrew.simonsimcity.update-notifier.err</string>    <key>StandardOutPath</key>    <string>/tmp/homebrew.simonsimcity.update-notifier.out</string>    <key>StartCalendarInterval</key>    <array>        <dict>            <key>Hour</key>            <integer>10</integer>            <key>Minute</key>            <integer>0</integer>        </dict>        <dict>            <key>Hour</key>            <integer>15</integer>            <key>Minute</key>            <integer>0</integer>        </dict>    </array></dict></plist>

You will now be notified if a new update is available. Call brew upgrade if you feel outdated, or include it in the script.

There's probably something wrong with your bash configuration. Make sure you set the PATH so that it contains the directory that brew is in. You may have it set in your ~/.profile but make sure it's also set in your ~/.bashrc. Alternatively, you could set it in your crontab in the same way you set MAILTO