Bash script to backup calendars and addressbooks from a local ownCloud/Nextcloud installation
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Bernhard Ostertag c21e114128
fix date
2 months ago
examples add option -one|--one-file-per-component 1 year ago
.gitignore improve option parsing. Update, todo.txt, examples/calcardbackup.config.example 4 years ago
LICENSE.txt renamed LICENSE.txt, added license boilerplate AGPLv3 4 years ago add brief note about unescaped percent signs (%) in crontab files 6 months ago add brief note about unescaped percent signs (%) in crontab files 6 months ago
calcardbackup release v1.9.0 2 months ago
changelog fix date 2 months ago


🇩🇪 auf deutsch lesen...

This Bash script exports calendars and addressbooks from ownCloud/Nextcloud to .ics and .vcf files and saves them to a compressed file. Additional options are available.



  • local installation of ownCloud/Nextcloud >= 5.0 with MySQL/MariaDB, PostgreSQL or SQLite3
  • command line client appropriate for database type
  • the user running the script needs to be able to read the full path to ownClouds/Nextclouds config.php, to the script itself and all used configuration files
  • GNU Bash >= 4.2 (check with bash --version)
  • optional: package gnupg to encrypt backup
  • optional: package zip to compress backup as zip-file (instead of tar.gz)
  • optional: package curl when using deprecated option -g|--get-via-http

Quick Installation Guide

  1. Clone the repository to your server (outside of webroot!) and enter the repo:
    git clone
    cd calcardbackup

  2. Change the ownership of repo to your webserver's user (here www-data):
    sudo chown -R www-data:www-data .

  3. Run the script as your webserver's user (here www-data) and give as first argument the path to your ownCloud/Nextcloud instance (here /var/www/nextcloud):
    sudo -u www-data ./calcardbackup "/var/www/nextcloud"

  4. Check output of script - it will tell, if it needs any other options.

  5. Find your backup in directory backups/.

There are many more options available: have a look at sections Options and Usage examples.

optional: setup a cronjob for an automatic daily run

Once calcardbackup runs without errors, a cronjob can be setup to run it automatically each day as follows:

  1. create a logfile and transfer its ownership to the webserver's user (here www-data):
    sudo touch /var/log/calcardbackup.log
    sudo chown www-data:www-data /var/log/calcardbackup.log

  2. edit the cron table of the webserver's user (here www-data) with:
    sudo crontab -u www-data -e
    and add the following line to the end of the file (change paths to fit your setup!):

    0 2 * * * /path/to/calcardbackup/calcardbackup "/var/www/nextcloud" > /var/log/calcardbackup.log 2>&1

Cron will now execute calcardbackup each day at 02:00am.
The output of the last run is written to /var/log/calcardbackup.log.

Take into account that percent signs (%) need to be escaped to prevent cron from changing them into newline characters.

Upgrading calcardbackup

If you followed the instructions in the Quick Installation Guide, you just need to pull the new version to upgrade to the latest version:

cd /path/to/calcardbackup
sudo -u www-data git pull

When migrating from GitHub to Codeberg, you need to execute the following command once before pulling the new version:

sudo -u www-data git remote set-url origin ""

⚠️ IMPORTANT: users upgrading calcardbackup from a version <= 0.7.2 are strongly advised to delete the file with users credentials (it is not needed anymore)!


All options can be specified in a configuration file or as command line arguments. If started with no options at all or only -b|--batch, the script attempts to use file calcardbackup.conf in the script's directory as configuration file.
If no configuration file via option -c|--configfile is given, the path to your ownCloud/Nextcloud instance must be the very first argument.
Find detailed description of all available options below.

Usage: ./calcardbackup [DIRECTORY] [option [argument]] [option [argument]] [option [argument]] ...

Arguments in capital letters to options are mandatory.
Paths (FILE / DIRECTORY) are absolute paths or relative paths to working directory.
If a path begins with a tilde-slash combinantion ~/, the tilde is replaced with ${HOME}

-a | --address URL
       Pass URL of ownCloud Installation to script.
       Only required when using option '-g|--get-via-http' for ownCloud < 7.0
-b | --batch
       Batch mode: print nothing to stdout, except for path to backup.
       Depending on configuration this will be:
         - absolute path of compressed backup file
       or, if run with option '-x|--uncompressed' (see below),
         - absolute path of directory containing uncompressed files
-c | --configfile FILE
       Read configuration from FILE. See 'examples/calcardbackup.conf.example'
       All other options except for '-b|--batch' will be ignored!
-d | --date FORMAT
       Use FORMAT as file name extension for backup directory or compressed backup file.
       FORMAT needs to be a format descriptor of the command date().
       The default is -%Y-%m-%d and will result in a directory or file
       named: 'calcardbackup-2017-03-23' or 'calcardbackup-2017-03-23.tar.gz'
       Check 'man date' for more info about different formats and syntax.
-e | --encrypt FILE
       Encrypt backup file with AES256 (gnupg). First line of FILE will be used as passphrase
-g | --get-via-http
       NOTE: this option is deprecated and might be removed in a future version of calcardbackup;
       it is only available to provide backwards compatibility.
       Get calendar/addressbooks via http request from the ownCloud/Nextcloud server.
       When using this option, a file with usernames and according cleartext passwords (see option
       '-u|--usersfile') is mandatory.
       This used to be the default behaviour until calcardbackup <= 0.7.2, but is not recommended
       anymore due to the security issue of cleartext passwords in a separate file.
-h | --help
       Print version number and a short help text 
-i | --include-shares
       Backup shared addressbooks/calendars, too, but only once: e.g. a shared calendar
       won't be backed up if the same calendar was already backed up for another user.
       NOTE: this option will be ignored if not used together with option '-u|--usersfile'.
-ltm | --like-time-machine N
       keep all backups for the last N days, keep only backups created on mondays for the time before.
-na | --no-addressbooks
       Do not backup addressbooks
-nc | --no-calendars
       Do not backup calendars
-o | --output DIRECTORY
       Use directory DIRECTORY to store backups.
       If this option is not given, folder 'backups/' in script's directory is created and used.
-one | --one-file-per-component
       Save each calendar component (e.g. event) and each addressbook component to a separate file
       In this mode, calcardbackup does not modify the data read from the database except for
       adding CR+LF at the end of the lines according to RFC5545/RFC6350.
       Use this option to investigate faulty database entries or to migrate calendars/addressbooks
       to a Radicale caldav/carddav Server or to vdirsyncer.
       NOTE: this option will be ignored if used together with deprecated option '-g|--get-via-http'
-p | --snap
       This option is mandatory if you are running nextcloud-snap
       ( With this option, calcardbackup has to be
       run with sudo (even running as root without sudo will fail!).
-r | --remove N
       Remove backups older than N days from backup folder (N needs to be a positive integer).
-s | --selfsigned
       Let cURL ignore an untrustful (e.g. selfsigned) certificate. With option -g, this is
       mandatory for backup in that case. In any case, cURL is used to retrieve status.php
       of the ownCloud/Nextcloud installation to perform some additional checks. If cURL
       can't access the URL due to an untrustful certificate, calcardbackup will run without
       executing these checks.
-u | --usersfile FILE
       Give location of FILE, which contains users to be backed up. One user per line.
       See 'examples/users.txt.example'
       NOTE: this file is mandatory when run with option '-g|--get-via-http'. In this case
       also passwords of the users to be backed up have to be given in FILE separated by a
       colon from the username. See 'examples/users.txt.example'
-x | --uncompressed
       Do not compress backup folder
-z | --zip
       Use zip to compress backup folder instead of creating a gzipped tarball (tar.gz)

NOTE:  Option '-f|--fetch-from-database' (introduced with calcardbackup 0.6.0) is set as
       default for calcardbackup >= 0.8.0, thus it has no function anymore.

Usage Examples

  1. ./calcardbackup /var/www/nextcloud -nc -x
    Do not backup calendars (-nc) and store backed up files uncompressed (-x) in folder named calcardbackup-YYYY-MM-DD (default) under ./backups/ (default).

  2. ./calcardbackup /var/www/nextcloud --no-calendars --uncompressed
    This is exactly the same command as above but with long options instead of short options.

  3. ./calcardbackup -c /etc/calcardbackup.conf
    Use configuration file /etc/calcardbackup.conf (-c /etc/calcardbackup.conf). Parameters for desired behaviour have to be given in that file (see examples/calcardbackup.conf.example).
    Don't give any other command line options in this case, because they will be ignored (except for -b|--batch).

  4. ./calcardbackup
    Use file calcardbackup.conf in the script's directory as configuration file.
    This is basically the same as example no.3, but with the default location of the configuration file.

  5. ./calcardbackup /var/www/nextcloud -b -d .%d.%H -z -e /home/tom/key -o /media/data/backupfolder/ -u /etc/calcardbackupusers -i -r 15
    Suppress output except for path to the backup (-b), use file name extension .DD.HH (-d .%d.%H), zip backup (-z), encrypt the zipped backup with using the first line in file /home/tom/key as encryption-key (-e /home/tom/key), save backup in folder /media/data/backupfolder/ (-o /media/data/backupfolder/), only back up items of usernames given in file /etc/calcardbackupusers (-u /etc/calcardbackupusers), include users' shared address books/calendars (-i) and delete all backups older than 15 days (-r 15).

  6. sudo ./calcardbackup /var/snap/nextcloud/current/nextcloud -p
    This example is for nextcloud-snap users. calcardbackup will use the cli utility from nextcloud-snap to access the database (-p) and backup all calendars/addressbooks found in the database.

  7. ./calcardbackup /var/www/nextcloud -ltm 30 -r 180
    Keep all backups for the last 30 days, but keep only backups created on mondays for the time before (-ltm 30) and remove all backups older than 180 days (-r 180).
    ⚠️ Make sure backups are also created on mondays when using option -ltm

Nextcloud-Snap Users

If you are running Nextcloud-Snap, you have to use option -p|--snap to tell calcardbackup to use the cli utility nextcloud.mysql-client from the snap package.
In order for this to work, calcardbackup has to be run with sudo (even running as root without sudo will fail).
As path to Nextcloud use the path to the configuration files of nextcloud. In a standard installation this would be /var/snap/nextcloud/current/nextcloud. See usage example no.6.

Syncloud Users

When using syncloud you must run the script as user nextcloud, add the path to the snap binaries to the PATH variable and use option -p when running calcardbackup:

sudo -u nextcloud PATH="${PATH}:/snap/bin" ./calcardbackup "/var/snap/nextcloud/current/nextcloud" -p

There is also a small code example on how to use calcardbackup in the wiki of the syncloud platform.

Synology Users

In Synology DiskStation Manager (DSM) the path to mysql needs to be added to the PATH variable before running calcardbackup. Example:

sudo -u http PATH="${PATH}:/usr/local/mariadb10/bin" ./calcardbackup "/volume1/web/nextcloud"

Considerations about Encryption

If you want to use the included encryption possibility, be aware that:

  • the files are encrypted by GnuPG, AES256 with the passphrase given in a separate file
  • the passphrase is stored in a file. Other users with access to the server might be able to see the passphrase.
  • calcardbackup is designed to run without user interaction, so there can't be a rock solid encryption. I consider the offered one as sufficient in most cases though.
  • if you need rock solid encryption, don't let calcardbackup encrypt the backup. Instead, encrypt it yourself.
  • command to decrypt (you will be prompted to enter the passphrase):

Does this also work with a broken ownCloud/Nextcloud instance?

Yes, it does! 😃

calcardbackup only needs the database (and access to it) from an ownCloud/Nextcloud installation to be able to extract calendars/addressbooks from the database and save them as .ics and .vcf files.
Here is how this can be accomplished:

  1. create a dummy Nextcloud directory including subdirectory config:
    mkdir -p /usr/local/bin/nextcloud_dummy/config

  2. create and edit file config.php to fit your needs as follows:
    nano /usr/local/bin/nextcloud_dummy/config/config.php

    • add database type according to config.sample.php

    • for MySQL/MariaDB/PostgreSQL:

    • for SQLite3:

      • add path to the nextcloud_dummy folder as 'datadirectory' according to config.sample.php
      • copy the SQLite3 database to the nexcloud_dummy directory (filename of the SQLite3 database must be owncloud.db):
        cp /path/to/owncloud.db /usr/local/bin/nextcloud_dummy/owncloud.db
    • if the database belongs to an installation of ownCloud <= 8.2, the following line needs to be added:
      'version' => '8.0.0',

  3. run calcardbackup and give as first argument the path to dummy Nextcloud directory created in step 1:
    ./calcardbackup /usr/local/bin/nextcloud_dummy

Blog articles about calcardbackup

Media coverage

Docker Image for calcardbackup

ICS and VCF standard

  • RFC 5545 - Internet Calendaring and Scheduling Core Object Specification (iCalendar)
  • RFC 6350 - vCard Format Specification

Exporter Plugins from SabreDAV used by ownCloud/Nextcloud



About Deprecated Option -g | --get-via-http

⚠️ This option is deprecated and not recommended anymore due to the necessity to give cleartext passwords in a separate file! It might be removed in a future version of calcardbackup.

As its default, calcardbackup creates calendar and addressbook backups by fetching the according data directly from the database. However, if invoked with option -g|--get-via-http, calcardbackup is using the legacy method of backing up addressbooks and calendars by downloading the according files from the ownCloud/Nextcloud webinterface. Thus, a file with usernames and passwords is necessary, passed to the script via option -u|--usersfile FILE.

Using this option also carries the risk of timeouts resulting in calcardbackup not being able to back up large addressbooks.

To make a long story short: all you need to know about option -g|--get-via-http is to NOT use it, unless you have a good reason to expose passwords of the users to be backed up.