JII (Java Image Info) Version 1.2.0

Version 1.2.0 of JII has been released.

It provides a clean interface to a collection of Java libraries and source code to read basic properties of images.


  • updated java to 11
  • rewritten the ProcessBuilderWrapper
  • fixed call of identify (imagemagick)
  • changed repo

Since this version JII gets it’s own maven repository.

The following entries are required in the pom.xml:



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How to check, if there is an update for mailcow

Let us assume that mailcow (dockerized) is installed in the directory /opt/mailcow-dockerized, then the script below checks, if there is an update and sends an email to the hostmaster:

set -o nounset
set -o errexit

cd /opt/mailcow-dockerized && ./update.sh --check > /dev/null

[ $exit_code -eq 0 ] && echo -e "Subject:MAILCOW: Update available \n\n Update your mailcow instance please!\n" | sendmail hostmaster@your-domain.com
exit 0

The scrip can be run as cron.

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MySQL: backup databases in separate files and zip it to STDOUT

It’s not very comfortable to restore one database, if you have just one big fat backup file, which contains all databases.

My solution is the bash script above does the following steps:

  1. It crreates one dump file for each database.
  2. It packs all dump files in one zipfile
  3. and sends it to STDOUT.

Step 3 is very helpful e.g. for using this script with backup software like rsnapshot.

## Dumps every database to a single file, all dump files will be zipped and redirected to the stdout.
## Usage: backup-db.sh > databases.zip
#! /bin/bash
set -o nounset
set -o errexit

trap 'rm -rf "$BACKUP_DIR"' EXIT
BACKUP_DIR=$(mktemp -d)

databases=`$MYSQL --defaults-extra-file=/etc/mysql/credentials.cnf --default-character-set=utf8mb4 -e "SHOW DATABASES;" \
        | grep -Ev "(Database|information_schema|performance_schema)"`
for db in $databases; do
  $MYSQLDUMP --defaults-extra-file=/etc/mysql/credentials.cnf --default-character-set=utf8mb4 --force --opt --databases $db \
        > "$BACKUP_DIR/$db.sql"
zip -rjq - "$BACKUP_DIR"
exit 0

The corresponding gist at github: https://gist.github.com/th-schwarz/38dd9fa1cdba05506f642a633095bad7

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dnsmasq and logrotate on ubuntu 20.04

I had same issues with dnsmasq and logrotate on ubuntu 20.04. Here is my solution:

In /etc/dnsmasq.conf the following entry is required:


Create /etc/logrotate.d/dnsmasq with the following content:

/var/log/dnsmasq/dnsmasq.log {
   size 100M
   rotate 7
      service dnsmasq restart

The important thing was the restart of dnsmasq!

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How to check the expiration date of a ssl certificate?

To check a certificate of an host:

openssl s_client -servername your.domain -connect your.domain:443 2>&- | openssl x509 -enddate -noout | sed 's/^notAfter=//g'

To check a certificate file:

openssl x509 -noout -enddate -in your.crt | sed 's/^notAfter=//g'



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