Which environment variable overrides the default system time zone for a session application?

The environment variable that overrides the default system time zone for a session application is TZ. This variable is used in Unix-like operating systems to specify the time zone that should be applied for date and time calculations within the session where the variable is set. When you set the TZ variable, it can take various formats including specifying a time zone abbreviation or a full time zone name.

Using the TZ variable allows for flexibility in managing time zones, especially when applications or scripts need to operate in contexts different from the server's default time zone. By modifying this variable, any processes or applications launched in that environment will adhere to the specified time zone rather than the system's default setting.

Other options, such as TIMEZONE, TIME, and LC_TIME, do not serve this specific purpose of overriding the time zone for the session. TIMEZONE is not a standard variable recognized by most Unix-like systems, while TIME generally refers to a specific point in time rather than a time zone setting. LC_TIME is part of the locale settings which handle formatting of date and time information, but it does not override the system time zone in the way TZ does.