Performing actions Before and After the backup task

This documentation is for an older version of CCC. You can find the latest version here.
Last updated on December 11, 2017

Often when you have a backup task that runs on a scheduled basis, there are associated tasks that you would like to perform before or after files are actually copied. CCC offers the option to run shell scripts before and after a backup task, unmount or set the destination as the startup disk, run another CCC backup task, and power management options such as restart and shutdown. If you would like to perform any of these pre or post clone tasks, click on the "Use Advanced Settings" button at the bottom of CCC's window.

Mounting the source or destination volume before a backup task begins

Without any additional configuration, CCC will attempt to mount your source and destination volumes before a backup task begins. This applies to many different volume types — ordinary volumes on locally-attached hard drives, disk images, network volumes, and encrypted volumes. If your source or destination volume is on a disk that is physically attached to your Mac (e.g. via Firewire, Thunderbolt, or USB), but it is not mounted, CCC can "see" that device and will attempt to mount it. If your source or destination is a network volume, CCC will obtain the credentials that you use to mount that device when you create the backup task, and will use those credentials to mount the volume before the task begins.

This also applies for nested volumes. For example, suppose you are backing up to a disk image on a network volume. CCC will first attempt to mount the network volume, then it will attempt to mount the disk image. Likewise, suppose you have a task configured to back up the contents of a folder on an encrypted volume. If you have saved the encrypted volume's passphrase in CCC's keychain, CCC will unlock and mount the encrypted volume before the backup task begins.

CCC's attempts to mount the source and destination volumes occur automatically before any other tasks, including pre clone shell scripts (described below), therefore it is not necessary to implement a shell script to pre-mount the source or destination.

Performing automated tasks before and after copying files

Destination volume options

If you would like CCC to unmount your destination volume at the end of the backup task, choose "Unmount the destination volume" from the Destination volume management menu. If your destination is a folder, the text will be "Unmount the underlying volume". If the destination is a disk image, CCC always unmounts the disk image volume, so this setting refers to the underlying physical volume upon which the disk image resides.

CCC will not forcefully unmount the destination volume. If an application has open files on the destination volume, CCC's attempt to unmount the volume will fail. CCC does not report this as an error, though it will make a note of it in the task's history.

If you would like to set the destination volume as the startup disk, for example to automate the regular testing of your backup volume, choose "Set as the startup disk" from the Destination volume management menu. El Capitan users note: CCC cannot change the startup disk setting if System Integrity Protection is enabled. We do not recommend disabling System Integrity Protection to make this feature work, rather we recommend that you use the Startup Disk Preference Pane to change the startup disk selection.

Power management options

By default, at the end of a backup task, CCC will not perform any power management tasks. Instead, the system will perform as defined by the settings in the Energy Saver preference pane. For example, if you have the system configured to idle sleep after 20 minutes, the system will go to sleep if there hasn't been any user activity in the last 20 minutes. CCC activity is not considered user activity, so often the system will go to sleep immediately after CCC finishes a backup task.

If you choose one of the options from the Power management menu, CCC will reboot or shut down your Mac when the backup task finishes. The reboot and shutdown options are not forceful. If you have a document open with unsaved modifications, for example, the application would prompt you to save the document. If a save dialog is not attended to, the shutdown or reboot request will time out.

Turn off the computer if it was previously off

If your backup task is scheduled to run on a regular basis, this option will be enabled in the Power Management popup menu. This option is applicable if you would like to have CCC shut down your Mac at the end of the task, but only in cases where the Mac was booted at the task's scheduled run time. If your backup task runs when the system has been on for a while or has been sleeping, CCC will not shut down the Mac when using this option.

Power Management options are ignored in some cases

Power management options will not be applied to backup tasks that are cancelled (e.g. you click the Stop button). Additionally, power management tasks will not be applied if other CCC backup tasks are running or queued to run immediately after the current task finishes running.

Power Management options are applied regardless of task success

Power management options will be applied whether the backup task completes successfully or not. If you prefer for a backup task to perform the power management action only when the backup task exits without error, see the postflight script below.

Run another backup task (task chaining)

If you have more than one CCC backup task configured, the other tasks will be listed in this popup menu. To create a task chain (e.g. to run tasks sequentially), simply choose one of these tasks to have that task run automatically after the current task finishes. Tasks run in this manner will start after the current task has finished completely. Chained tasks will run regardless of the exit status of a preceding task in the chain, e.g. if the first task reports errors or fails to run at all, the second task will still run.

Running shell scripts before and after the backup task

If there is functionality that you need that does not exist within CCC, pre and post clone shell scripts may be the solution for you. Pre clone shell scripts run after CCC has performed "sanity" checks (e.g. are the source and destination volumes present, is connectivity to a remote Macintosh established) but before copying files. Post-clone shell scripts run after CCC has finished copying files and performing its own internal cleanup, but before unmounting any volumes.

CCC passes several parameters to pre and post clone shell scripts. For example, the following shell script:


echo "Running $0"
echo `date`
echo "Source: $1"
echo "Destination: $2"
echo "Third argument: $3" # Exit status for post-clone scripts, underlying volume path for a disk image for pre-clone scripts
echo "Fourth argument: $4" # Destination disk image path, if applicable


Would produce the following output (you can redirect this output to a file of your own specification) if implemented as a post clone script:


Running /Library/Application Support/com.bombich.ccc/Scripts/
Wed Oct 8 21:55:28 EDT 2014
Source: /
Destination: /Volumes/Offsite Backup
Third argument: 0
Fourth argument:

First parameter

The path to the source volume or folder.

Second parameter

The path to the destination volume or folder. If the destination is a disk image, this is the path to the mounted disk image.

Third parameter

The contents of this parameter has changed since CCC 3, so take care to update the logic in any shell scripts that you used with earlier versions of CCC.

  • Pre clone script: The underlying mountpoint for the volume that holds the destination disk image, if applicable.
  • Post clone script: The exit status of the file copying phase of the backup task.

Fourth parameter

The path to the destination disk image, if applicable. The contents of this parameter has changed since CCC 3, so take care to update the logic in any shell scripts that you used with earlier versions of CCC.

If your pre clone script exits with a non-zero exit status, it will cause CCC to abort the backup task. This can be used to your advantage if you want to apply preconditions to your backup operation. If you want to be certain that errors in your pre clone shell script never cause the backup task to be aborted, add "exit 0" to the end of your script. If you would like that script to silently cancel the backup task, add "exit 89" to the end of the script. If the script is a global preflight script (specified in the Advanced section of CCC's Preferences window), you can add "exit 104" to the end of the script to cancel the backup task and to avoid recording a Task History event.

The post clone script will run whether the backup task exits successfully or not. If your script should behave differently depending on the result of the task, you can test whether the third parameter is zero (an exit status of "0" means the task ended successfully). For example:



if [ "$exitStatus" = "0" ]; then
    # foo
    # bar

If your postflight script exits with a non-zero exit status, CCC will not report this as a failure of the backup task. The failure will be noted in the Task History window, however.

AppleScripts are not supported

You cannot specify an AppleScript as a pre or post clone script, CCC currently only supports running shell scripts.

Shell scripts require a shell interpreter line

CCC does not assume a default shell environment when running your pre or postflight script. Not doing so gives users a great deal of flexibility; they can choose to write their scripts in any shell or programming language (e.g. bash, python, perl, ruby, C). For CCC to execute a shell script as an application, though, the system needs to know what shell should be used to interpret the script, and that value needs to be defined in your shell script. This is done simply by placing a shell interpreter line at the top of the file, e.g. #!/bin/sh.

Security implications of pre and post clone shell scripts

CCC's pre and post clone shell scripts are executed as the System Administrator. To prevent non-administrative users from making unauthorized modifications to your shell scripts, you should restrict which users have write access to these scripts and to the folder in which they are contained. The parent folder and scripts should be writable only by the owner (e.g. you). For example, running the following in the Terminal application would secure any shell scripts located in the default location for pre and post clone scripts:

chmod 755 /Library/Application\ Support/com.bombich.ccc/Scripts/*.sh

Example pre and post clone shell scripts

To use any of these example scripts, download the script and place it somewhere on your startup disk. By default, CCC looks in /Library/Application Support/com.bombich.ccc/Scripts.
This is a pre clone script that you can use to pause all currently-running Parallels VM containers. This script will also retain state information that can be read by the corresponding post clone script to resume these VMs after the backup task has completed. Note: This script relies on command-line tools offered only in Parallels Desktop for Mac Pro or Business Edition.
This post clone script will resume any Parallels VM containers that were suspended by the pre clone script. Note: This script relies on command-line tools offered only in Parallels Desktop for Mac Pro or Business Edition.
If you want to play a unique sound, use this script. You can plug in the path to any audio file of your liking or try one of the examples included.
CCC's option to automatically unmount the destination volume is a volume-level task, not a device task. If you want to eject the destination device, use this post clone script instead. Note that ejecting the destination device will unmount all volumes on the device. Also note that this example script adds a 60-second delay to accommodate macOS's desire to automatically regenerate various cache files. This delay can be adjusted if necessary by editing the script.
This post clone script will rename the destination disk image, adding a timestamp to the disk image name. This is useful if you want to create snapshots of the source in disk image files for posterity. Note that this will cause CCC to create a new disk image during every backup task, and recopy everything from the source each time. Additional notes for configuring this post clone script are available in the script header.
This post clone script will perform the requested power management option (e.g. shutdown, restart, sleep) at the end of the backup task if the backup task completes without errors. Use this in lieu of one of the Power Management postflight options if you prefer the power management action does not occur when a task ends with errors (e.g. if the destination volume is missing). and
This pair of scripts can be used to quit and open an application before and after the backup task. Open these scripts in a text editor to define the application that should be quit or opened.
This postflight script will post the status of your backup task to a Slack channel.
This postflight script will post an IFTTT Maker Event of the status of your backup task.