Support multiple instances installation

[didierm]

We run multiple instances with the same codebase, by using the NEXTCLOUD_CONFIG_DIR variable (nextcloud/server#300).

In order for calcardbackup to support multiple instances, I propose the following patch :

# location of ownClouds/Nextclouds config.php:
configphp="${nextcloud_path}/config/config.php"

to

# location of ownClouds/Nextclouds config.php:
[[ -z "${NEXTCLOUD_CONFIG_DIR:-}" ]] && configphp="${nextcloud_path}/config/config.php" || configphp="${NEXTCLOUD_CONFIG_DIR}/config.php"

[BernieO]

On a first glance this looks good to me.
I will have a closer look into this the next couple of days.

[BernieO]

I saw that this is also possible with ownCloud: owncloud/core#27874

support for environment variables NEXTCLOUD_CONFIG_DIR and OWNCLOUD_CONFIG_DIR is been added with commit 279b923 (until release of the next version only in the testing branch)

However, if both environment variables are set, calcardbackup will exit with an error, because the script does not know which one to use. In this case one of the environment variables has to be unset for the script to work.

@didierm: could you check whether that does the trick for your use case? Thanks.

[didierm]

Tested (ver. 0.7.2-24 (13.10.2018)) with NEXTCLOUD_CONFIG_DIR ; works perfect.
Thanks a lot !