TransferLog

TransferLog is a directive used in the Apache HTTP Server to specify a separate log file for transferred data. It is part of the server’s logging directives that record HTTP transactions. Historically present in early Apache versions and still recognized for compatibility in newer releases, it has been largely superseded by the CustomLog directive, which provides more explicit control over log formats and destinations.

Syntax: TransferLog file-path. The file path can be an absolute path or relative to the server’s runtime directory; a dash "-" may indicate standard output. Entries are written using the server’s current access-log style, typically aligned with the Common Log Format or the Combined Log Format, depending on configuration and the active LogFormat settings.

Usage: When enabled, each completed HTTP transaction is appended to the specified log file. The exact fields included in each entry depend on the configured LogFormat, which determines the information recorded about the client, request, response, and transfer size.

Compatibility and modernization: In contemporary configurations, the CustomLog directive is preferred because it allows explicit specification of log formats and multiple log files on a per-virtual-host basis. TransferLog remains for backward compatibility in older configurations, but migrating to CustomLog is recommended for better consistency and flexibility across the server’s logging setup.

See also: CustomLog, LogFormat, mod_log_config.