Master Linux Commands, Zimbra Mail, and Bash Scripts: A Comprehensive Guide

A docker mailserver upgrade from 15.x to 16.x is not just a new image tag. Version 16.0.0 moves the image from Debian 12 to Debian 13 and from Dovecot 2.3 to Dovecot 2.4. Your mail and accounts survive the switch, but an old dovecot.cf with 2.3 setting names stops Dovecot completely, SA_SPAM_SUBJECT is rejected, and DHE ciphers disappear from ports 587 and 993. The container still reports "up and running". Below is the full upgrade on a test server, what broke and the exact fixes. Lab: docker-mailserver 15.1.0 upgraded to 16.0.1 on the same volumes, rootless podman 5.8 (the docker commands are identical), a Debian 13 client container with swaks, curl and openssl, October 2026. Every output below comes from that lab. Sources: the docker-mailserver v16.0.0 release , its CHANGELOG and the Dovecot 2.3 to 2.4 upgrade guide . Docker mailserver upgrade to v16, in short: Back up docker-data/dms/ and stop the container. Rename 2.3 settings in config/dovecot.cf (for exampl...

Since docker-mailserver v16.0.0 the image ships a docker mailserver healthcheck out of the box: a script called dms-healthcheck and a HEALTHCHECK --start-period=30s CMD dms-healthcheck line in the Dockerfile. The script checks that every supervisor service your configuration enables (Postfix, Dovecot, cron, rsyslog, OpenDKIM, Rspamd and so on) is RUNNING . On Docker the container then shows (healthy) or (unhealthy) with no extra configuration. On podman the image healthcheck is not used at all, so you have to add --health-cmd dms-healthcheck yourself. Every example below was tested on 2026-10-22 with mailserver/docker-mailserver:16.0.1 and :15.1.0 on Docker Engine 29.9.1 (the official docker:29.9.1-dind image) with Docker Compose v5.6.0, and with ghcr.io/docker-mailserver/docker-mailserver:16.0.1 on rootless podman 5.8.9. Rspamd, OpenDKIM, OpenDMARC, Amavis, ClamAV, Fail2Ban and Postgrey were disabled to keep the lab small. All output is copied from the lab. Contents What ...

The quickest WireGuard Docker setup is the lscr.io/linuxserver/wireguard image with a short compose.yaml : set PEERS and SERVERURL , publish UDP port 51820, add the NET_ADMIN capability and the src_valid_mark sysctl, then run docker compose up -d . The container generates the server config and one ready-to-import client config (plus QR code) per peer. This guide shows the whole setup with real output, a working client, and the four mistakes that leave you with a tunnel that never connects. Tested on 2026-10-23 on a Debian 12 KVM virtual machine (kernel 6.1.0-47-amd64) with Docker Engine 29.9.2 and Docker Compose v5.6.1, using image tag 1.0.20260223-r0-ls127 , the newest release that day. A second container on the same VM played the role of a remote laptop and connected to the VM's IP 192.168.121.137. Private and preshared keys are shortened in the output below; everything else is copied from the lab. Contents What you need for WireGuard Docker Step 1: compose.yaml for the W...

To compile Linux kernel source on Debian or Ubuntu: install build-essential flex bison bc libssl-dev libelf-dev , download and verify the tarball from kernel.org, copy your running config with cp /boot/config-$(uname -r) .config , run make olddefconfig , build with make -j$(nproc) , then sudo make modules_install and sudo make install and reboot. This guide walks through every step with real output, including the four build errors you get when a package is missing and the certificate error that stops most Ubuntu builds. Every command used to compile Linux kernel 7.2.12 below was run on 2026-10-23 in a Debian 12 (bookworm) KVM virtual machine with 12 vCPUs and 5 GiB RAM, gcc 12.2.0 and binutils 2.40, building Linux 7.2.12, the latest stable release on kernel.org that day. The VM started on the distro kernel 6.1.0-47-amd64. All output is copied from two lab runs. Contents What you need before you compile Linux kernel source Step 1: download and verify the source before you compile ...

A bash yes no prompt is a read -r -p "Question? [y/N] " ans followed by a case on the answer. The short version that most tutorials show works for a quick test, but it treats "yolo" as yes, loops forever when there is no terminal and silently skips the question when the script is piped. This guide shows a confirm function that handles all of that, plus Yes/No/Cancel, single-key answers, timeouts, select menus and unattended runs with -y . Every example was run on 2026-10-23 in a debian:trixie container with GNU bash 5.2.37 and dash as /bin/sh . The answers were typed on a real pseudo-terminal (util-linux script ), so the output below is exactly what a user sees at each bash yes no prompt, including the typed answer. Contents The classic bash yes no prompt and its problems A reusable bash yes no prompt function with a default Bash yes no prompt with Cancel in a loop Single key, timeout and select menu Bash yes no prompt in pipes, cron and CI POSIX sh version ...