Add an environment variable to disable logging to file

Fixes #8527

doc/man/wesnoth.6

@@ -191,7 +191,7 @@ lists defined log domains (only the ones containing
 if used) and exits
 .TP
 .B --no-log-to-file
-prevents redirecting logged output to a file. Log files are created in the logs directory under the userdata folder.
+prevents redirecting logged output to a file. The environment variable WESNOTH_NO_LOG_FILE can also be set as an alternative. Log files are created in the logs directory under the userdata folder.
 .TP
 .B --log-to-file
 log output is written to a file. Cancels the effect of --no-log-to-file whether implicit or explicit.

src/commandline_options.cpp

@@ -251,7 +251,7 @@ commandline_options::commandline_options(const std::vector<std::string>& args)
 		("log-debug", po::value<std::vector<std::string>>()->composing(), "sets the severity level of the specified log domain(s) to 'debug'. Similar to --log-error.")
 		("log-none", po::value<std::vector<std::string>>()->composing(), "sets the severity level of the specified log domain(s) to 'none'. Similar to --log-error.")
 		("log-precise", "shows the timestamps in log output with more precision.")
-		("no-log-to-file", "log output is written only to standard error rather than to a file.")
+		("no-log-to-file", "log output is written only to standard error rather than to a file. The environment variable WESNOTH_NO_LOG_FILE can also be set as an alternative.")
 		("log-to-file", "log output is written to a file. Cancels the effect of --no-log-to-file whether implicit or explicit.")
 		("wnoconsole", "For Windows, when used with --no-log-to-file, results in output being written to cerr/cout instead of CONOUT. Otherwise, does nothing.")
 		;

src/wesnoth.cpp

@@ -1041,7 +1041,7 @@ int main(int argc, char** argv)
 	// write_to_log_file means that writing to the log file will be done, if true.
 	// if false, output will be written to the terminal
 	// on windows, if wesnoth was not started from a console, then it will allocate one
-	bool write_to_log_file = true;
+	bool write_to_log_file = !getenv("WESNOTH_NO_LOG_FILE");
 	[[maybe_unused]]
 	bool no_con = false;