tmlatestbackup

Really simple CLI app to obtain the date of the last Mac OS Time Machine backup.

Install

The recommended installation option is use Homebrew with the command:

brew install bglezseoane/tap/tmlatestbackup

You can only install the program with Cargo, with the command:

cargo install tmlatestbackup

Use

The normal use of the tool is very simple. You only need to run:

tmlatestbackup

And obtain the date of the last Time Machine backup with format like: 2018-11-21-102312.

Achieve permissions against Mac OS System Integrity Protection

If your current terminal app has full disk access and you use tmlatestbackup since it, the tool will works fine. If you only want to work with tmlatestbackup since your terminal or since scripts used by you since your terminal, the above is sufficient and the following steps are irrelevant to your use case.

Otherwise, if you want to use the tool since an script routine as launchd agent, the tool is going to fail due to System Integrity Protection.

Mac OS System Integrity Protection block tmlatestbackup because the tool try to access protected Time Machine features and it doesn't inherit permissions —using it since the terminal, inherit terminal granted ones—. To achieve permissions, you need to grant them adding the binary (/usr/local/bin/tmlatestbackup) to the list of applications with full disk access —System Preferences > Security & Privacy > Full Disk Access > Add—.

The path /usr/local/bin/tmlatestbackup could be different if you have installed with Cargo. Any case, you can check it with which tmlatestbackup.

If your agent only needs to run the tool and no more stuff, you can add the following lines to the agent Info.plist and it will work (after previously indicated step):

<key>ProgramArguments</key>
    <array>
      	<string>/usr/local/bin/tmlatestbackup</string>
    </array>

For any reason, to work with the tool since the launchd agent and integrated in a shell script, you need to always run it as open -a '/usr/local/bin/tmlatestbackup' and not directly as a command (e.g. /usr/local/bin/tmlatestbackup). I.e., if you use, e.g., the following agent specification...

<key>ProgramArguments</key>
    <array>
      	<string>/Users/You/scripts/script_which_calls_tmlatestbackup.sh</string>
    </array>

... you need to run tmlatestbackup as follows:

# 'script_which_calls_tmlatestbackup.sh'
# ...

open -a '/usr/local/bin/tmlatestbackup'
# And not '/usr/local/bin/tmlatestbackup

# ...

When run with open -a, the command don't return an error code if the launched application fails, so in order to integrate this step in a well designed script, the next approach is recommended:

# ...

# Create temporary file to save the output of the 'open' command
TMP_OPEN_TMLATESTBACKUP_STDOUT=$(mktemp -t open_tmlatestbackup)

# Run and wait
open -W -a '/usr/local/bin/tmlatestbackup' \
	--stdout "$TMP_OPEN_TMLATESTBACKUP_STDOUT" \
	--stderr "$TMP_OPEN_TMLATESTBACKUP_STDOUT"

# Check and act attending to the process success
if ! [[ "$(cat "$TMP_OPEN_TMLATESTBACKUP_STDOUT")" \
	=~ ^[0-9]{4}-[0-9]{2}-[0-9]{2}-[0-9]{6}$ ]]
then
	>&2 echo "Error using 'tmlatestbackup'."
	rm "$TMP_OPEN_TMLATESTBACKUP_STDOUT"
	exit 1 
fi

# Clean
rm "$TMP_OPEN_TMLATESTBACKUP_STDOUT"

# ...

Motivation

On my Mac OS machine I have some scripts that cannot work as agents because it is prevented by System Integrity Protection, which only allows granting permissions to binary programs. That, coupled with the fact that I wanted to learn the Rust language, motivated me to write this simple program in order to have the conflicting step in a compiled program to authorize it and can maintain my script routine working elegantly —and not with pseudo-compiled shell scripts inserted in a compiled language program—. However, at the end of the day tmlatestbackup is a potentially useful generic purpose program.