On a systemd-based distribution, which file determines the local time zone used by the C library when formatting times?
LPIC-1 Exam 102-500, objective 108. Essential system services medium
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The options
Not correct /etc/timezone
Wrong. /etc/timezone exists only on Debian-family systems, where it records the zone name as plain text for the distribution's own tooling. The C library never reads it, and RHEL-family systems do not have it at all.
Correct /etc/localtime
Correct. /etc/localtime is the zone the C library actually uses. On systemd hosts it is a symlink into /usr/share/zoneinfo, for example /usr/share/zoneinfo/Europe/Berlin, and `timedatectl set-timezone` rewrites that symlink.
Not correct /usr/share/zoneinfo/UTC
Wrong. /usr/share/zoneinfo is the database of all zone definition files. UTC is just one entry in it; it is a candidate target for /etc/localtime, not the setting itself.
Not correct /etc/adjtime
Wrong. /etc/adjtime is written by hwclock. It records the RTC drift factor and whether the hardware clock is held in UTC or local time — not the system time zone.
Why
Time zone data lives in /usr/share/zoneinfo as compiled tzfile entries. /etc/localtime points at (or copies) the one entry in force for the whole system, and TZ in the environment overrides it per process. Debian additionally stores the zone name as text in /etc/timezone for its own tooling. `timedatectl list-timezones` enumerates the valid names and `timedatectl set-timezone <name>` applies one.
Where this comes from
- Cited
- LPI exam objective 108.1
- What it says
- Configure the time zone using the zone information database and the local time file.
Practise this
Reading one question is not practice. The trainer will draw a set from objective 108 and space the ones you get wrong.