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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.

:warning: Starting with version 0.8.0, there is no need anymore for a file with user credentials because all data is fetched directly from the database.
If only calendars/addressbooks of certain users shall be backed up, list them in users.txt without any passwords.

:bangbang: All users upgrading calcardbackup from a previous version to version 0.8.0 or above are strongly advised to delete the file with users credentials - or at least to remove the cleartext passwords from this file!



  • 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 https://github.com/BernieO/calcardbackup
    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.

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.


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.

-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. Items will only be backed up 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.
-p | --snap
       This option is mandatory if you are running nextcloud-snap
       (https://github.com/nextcloud/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'
       Due to option '-f|--fetch-from-database' being the default for calcardbackup >= 0.8.0
       there is no need anymore to give passwords in this file or to use this file at all.
       NOTE: this file is mandatory when run with option '-g|--get-via-http'
-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).
    :warning: Make sure backups are also created on mondays when using option -ltm

  8. ./calcardbackup /var/www/nextcloud -g -u /etc/calcardbackupusers -s -i
    Use the deprecated method and get the addressbook/calendar files via https-request from the ownCloud/Nextcloud webinterface (-g, deprecated), find usernames and according cleartext passwords of users to be backed up in file /etc/calcardbackupusers (-u calcardbackupusers, mandatory with option -g), tell calcardbackup that the server is using a selfsigned certificate (-s, only needed with option -g) and include shared items (-i). The backup will be saved as compressed *.tar.gz file named calcardbackup-YYYY-MM-DD.tar.gz (default) in folder ./backups/ (default).
    :warning: Using option -g is deprecated and not recommended anymore, due to the mandatory file with user credentials and other drawbacks! It might be removed in a future version of calcardbackup (see About Option -g|--get-via-http).

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.

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

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

:warning: 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.

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.

About Option -i | --include-shares

:warning: There is no need to read this section unless you want to run calcardbackup with the deprecated option -g|--get-via-http, which is not recommended (see About Option -g|--get-via-http).

If, for whatever reason, calcardbackup is being run with option -g|--get-via-http (not recommended!), this method may be used as follows to keep passwords of the main users secret:

  • create a new user in your ownCloud/Nextcloud
  • share addressbooks/calendars (to be backed up) with that new user
  • in users.txt give only the username and password of this new user
  • add option -i to back up shared items as well

Benefit of this approach: if the file users.txt gets in wrong hands, only this new user account is being compromised.
Drawback: no automatic inclusion of newly created addressbooks/calendars. Items will not be backed up unless being shared with that new user account.

Due to the new default behaviour of calcardbackup >= 0.8.0 (creating calendars/addressbooks by fetching data from the database), this option basically becomes pointless. If you still want to use this method of backing up shared items even without option -g, then there is of course no need to give passwords in the usernames file. If no usernames file is passed to the script via option -u, option -i will be ignored (because all existing calendars/addressbooks will be backed up anyway).

Blog articles about calcardbackup

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


calcardbackup: moved to https://codeberg.org/BernieO/calcardbackup

Calcardbackup Info

⭐ Stars 63
🔗 Source Code github.com
🕒 Last Update 8 months ago
🕒 Created 4 years ago
🐞 Open Issues 0
➗ Star-Issue Ratio Infinity
😎 Author BernieO