diff --git a/lyx.1in b/lyx.1in
index 6573d9594f..d753374f52 100644
--- a/lyx.1in
+++ b/lyx.1in
@@ -75,11 +75,13 @@ Note that the order of -e and -x switches matters.
 where fmt is the import format of choice and file.xxx is the file to be imported.
 .TP
 \fB \-f [\-\-force\-overwrite]\fP \fIwhat
-where what is is either "\fBall\fR" or "\fBmain\fR".
-Using "\fBall\fR", all files are overwritten during a batch export, otherwise
-only the main file will be. When this switch is followed by anything else other
-than "\fBall\fR" or "\fBmain\fR", the behavior is as if "\fBall\fR" was
-specified, but what follows is left on the command line for further processing.
+where what is is either "\fBall\fR", "\fBmain\fR" or "\fBnone\fR".
+Specify "\fBall\fR" to allow overwriting all files during a batch export,
+"\fBmain\fR" to allow overwriting the main file only, or "\fBnone\fR"
+to disallow overwriting any file. When this switch is followed by anything
+else other than "\fBall\fR", "\fBmain\fR" or "\fBnone\fR", the behavior is as
+if "\fBall\fR" was specified, but what follows is left on the command line for
+further processing.
 .TP
 .BI -batch
 causes LyX to run the given commands without opening a GUI window.
@@ -124,6 +126,17 @@ The user directory is, in order of precedence:
 .B LYX_LOCALEDIR
 can be used to tell LyX where to look for the translations of its GUI
 strings in other languages.
+
+.TP
+.B LYX_FORCE_OVERWRITE
+can be used to change the default behavior when exporting from command
+line.
+.PP
+By default, LyX overwrites the main file when exporting from command
+line but not the ancillary files. This behavior can be changed by setting
+this environment variable, which relieves the need of using the \-f switch.
+Allowed values are either "\fBall\fR", "\fBmain\fR" or "\fBnone\fR", with
+same meaning as for the \-f switch.
 .SH FILES
 .nf
 .ta \w'\fILIBDIR\fR/lyxrc.in  'u
diff --git a/src/LyX.cpp b/src/LyX.cpp
index fda6fc3602..15326e09da 100644
--- a/src/LyX.cpp
+++ b/src/LyX.cpp
@@ -91,9 +91,11 @@ bool use_gui = true;
 
 
 // Tell what files can be silently overwritten during batch export.
-// Possible values are: NO_FILES, MAIN_FILE, ALL_FILES.
+// Possible values are: NO_FILES, MAIN_FILE, ALL_FILES, UNSPECIFIED.
+// Unless specified on command line (through the -f switch) or through the
+// environment variable LYX_FORCE_OVERWRITE, the default will be MAIN_FILE.
 
-OverwriteFiles force_overwrite = NO_FILES;
+OverwriteFiles force_overwrite = UNSPECIFIED;
 
 
 namespace {
@@ -736,9 +738,20 @@ bool LyX::init()
 	if (queryUserLyXDir(package().explicit_user_support()))
 		reconfigureUserLyXDir();
 
-	// no need for a splash when there is no GUI
 	if (!use_gui) {
+		// No need for a splash when there is no GUI
 		first_start = false;
+		// Default is to overwrite the main file during export, unless
+		// the -f switch was specified or LYX_FORCE_OVERWRITE was set
+		if (force_overwrite == UNSPECIFIED) {
+			string const what = getEnv("LYX_FORCE_OVERWRITE");
+			if (what == "all")
+				force_overwrite = ALL_FILES;
+			else if (what == "none")
+				force_overwrite = NO_FILES;
+			else
+				force_overwrite = MAIN_FILE;
+		}
 	}
 
 	// This one is generated in user_support directory by lib/configure.py.
@@ -1012,9 +1025,9 @@ int parse_help(string const &, string const &, string &)
 		  "                  where fmt is the import format of choice\n"
 		  "                  and file.xxx is the file to be imported.\n"
 		  "\t-f [--force-overwrite] what\n"
-		  "                  where what is either `all' or `main'.\n"
-		  "                  Using `all', all files are overwritten during\n"
-		  "                  a batch export, otherwise only the main file will be.\n"
+		  "                  where what is either `all', `main' or `none',\n"
+		  "                  specifying whether all files, main file only, or no files,\n"
+		  "                  respectively, are to be overwritten during a batch export.\n"
 		  "                  Anything else is equivalent to `all', but is not consumed.\n"
 		  "\t-batch          execute commands without launching GUI and exit.\n"
 		  "\t-version        summarize version and build info\n"
@@ -1126,6 +1139,9 @@ int parse_force(string const & arg, string const &, string &)
 	} else if (arg == "main") {
 		force_overwrite = MAIN_FILE;
 		return 1;
+	} else if (arg == "none") {
+		force_overwrite = NO_FILES;
+		return 1;
 	}
 	force_overwrite = ALL_FILES;
 	return 0;
diff --git a/src/LyX.h b/src/LyX.h
index 57f5f515fe..0b578590fa 100644
--- a/src/LyX.h
+++ b/src/LyX.h
@@ -37,7 +37,8 @@ class SpellChecker;
 enum OverwriteFiles {
 	NO_FILES,
 	MAIN_FILE,
-	ALL_FILES
+	ALL_FILES,
+	UNSPECIFIED
 };
 
 extern bool use_gui;