namespaces: net mount procs
hosts: files dns
The local routing information may be corrupted and must be re-validated using a routing protocol.
One of the routers in the routing table is not available which causes the automatic router failure detection mechanism (ARF-D) to wait for a timeout.
There may accidentally be more than one default router in which case a default router election has to be done on the network in order to choose one router as the default.
The Linux Kernel Routing Daemon (LKRD) is not running and should be started using its init script or systemd unit.
DNS resolution may not be working as route by default tries to resolve names of routers and destinations and may run into a timeout.
The field is not changed during the transport of a package.
The field is transmitted within a hop-by-hop extension header.
Each router forwarding the packet increases the field’s value.
Each router forwarding the packet decreases the field’s value.
For multicast packages, the field’s value is always 1.
Network interfaces may become active or inactive.
New name servers may be added to the resolver configuration.
The system’s host name may change.
IP addresses may change.
The routing table may change.
UID have precedence over GIDs, therefore the user is available while the group doesn’t.
The user as well as the group are not available to avoid ambiguity due to the ID conflict.
UIDs and GIDs are independent of each other, therefore the user as well as the group are still available.
The user is the only member of the group, even if the group configuration contains other members.
GIDs have precedence over UIDs, therefore the group is available while the user isn’t.
The timestamp of the user’s last login
The user’s private SSH keys
The hashed password of the user
The numerical user ID (UID)
The path to the user’s home directory
Set the system’s date and time.
Set the system’s date but not the time.
Calculate the time span between two dates.
Print a calendar for a month or a year.
Display time in a specific format.
Commands the user can run using sudo.
The absolute path to the user’s home directory.
Which printers are available for the new user.
The SSH keys used to login to the new account.
The numeric user ID (UID) of the user.
It is a plain text file containing a string such as Europe/Berlin
It is created and maintained by the NTP service based on the location of the system’s IP address.
It is a symlink to /sys/device/clock/ltime and always contains the current local time.
After changing this file, newtzconfighas to be run to make the changes effective.
It is either a symlink to or a copy of a timezone information file such as /usr/share/zoneinfo/Europe/Berlin.
Timer units can only be defined within a service unit’s file.
The command executed by the timer is specified in the timer unit’s [Cmd] section.
A dedicated system service, systemd-cron, handles the execution of timer units.
Timer units only exist in the system scope and are not available for users.
Each systemd timer unit controls a specific systemd service unit.
Effective group ID
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