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- System and Service Manager
System and Service Manager systemd is a suite of basic building blocks for a Linux system It provides a system and service manager that runs as PID 1 and starts the rest of the system systemd provides aggressive parallelization capabilities, uses socket and D-Bus activation for starting services, offers on-demand starting of daemons, keeps track of processes using Linux control groups
- systemd Optimizations
Of course, before optimizing you should instrument the boot to generate profiling data, so make sure you know your way around with systemd-bootchart, systemd-analyze and pytimechart! Optimizations without profiling are premature optimizations! Note that systemd’s fast performance is a side effect of its design but wasn’t the primary design
- Credentials - systemd
System and Service Credentials The systemd service manager supports a “credential” concept for securely acquiring and passing credential data to systems and services The precise nature of the credential data is up to applications, but the concept is intended to provide systems and services with potentially security sensitive cryptographic keys, certificates, passwords, identity
- Frequently Asked Questions - systemd
Frequently Asked Questions Also check out the Tips Tricks! Q: How do I change the current runlevel? A: The concept of runlevels is obsolete A set of target units are exposed that carry similar semantics, e g runlevel 5 -> graphical target:
- Diagnosing Boot Problems - systemd
Diagnosing Boot Problems If your machine gets stuck during boot, first check if the hang happens before or after control passes to systemd Try to boot without rhgb and quiet on the kernel command line If you see some messages like these: Welcome to Fedora VERSION (codename)!” Starting name … [ OK ] Started name then systemd is running (See an actual screenshot ) Debugging always gets
- Container Interface - systemd
The Container Interface Also consult Writing Virtual Machine or Container Managers systemd has a number of interfaces for interacting with container managers, when systemd is used inside of an OS container If you work on a container manager, please consider supporting the following interfaces Execution Environment If the container manager wants to control the hostname for a container
- Known Environment Variables - systemd
Known Environment Variables A number of systemd components take additional runtime parameters via environment variables Many of these environment variables are not supported at the same level as command line switches and other interfaces are: we don’t document them in the man pages and we make no stability guarantees for them While they generally are unlikely to be dropped any time soon
- Boot Loader Interface - systemd
The Boot Loader Interface systemd can interface with the boot loader to receive performance data and other information, and pass control information This is only supported on EFI systems Data is transferred between the boot loader and systemd in EFI variables All EFI variables use the vendor UUID 4a67b082-0a4c-41cf-b6c7-440b29bb8c4f
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