diff --git a/custom/CHANGELOG b/custom/CHANGELOG
index c1c24313e..982b18257 100644
--- a/custom/CHANGELOG
+++ b/custom/CHANGELOG
@@ -32,3 +32,5 @@ Fixed a bug that broke remote command execution with parameters.
 Added a new parameter type for selecting multiple items from a menu.
 ---- Changes since 1.530 ----
 Added an option for custom commands to have their output displayed without any Webmin UI, in a selectable MIME type.
+---- Changes since 1.550 ----
+A default value for each custom command parameter can now be entered on the Edit Command form. Defaults can also be read from a file or shell command, if this behavior is enabled on the Module Config page. Thanks to Sart Cole for suggesting this feature.
diff --git a/custom/config b/custom/config
index 0a6ade13e..e31a0a466 100644
--- a/custom/config
+++ b/custom/config
@@ -1,2 +1,4 @@
 display_mode=0
 columns=2
+params_file=0
+params_cmd=0
diff --git a/custom/config-*-linux b/custom/config-*-linux
index 0a6ade13e..e31a0a466 100644
--- a/custom/config-*-linux
+++ b/custom/config-*-linux
@@ -1,2 +1,4 @@
 display_mode=0
 columns=2
+params_file=0
+params_cmd=0
diff --git a/custom/config.info b/custom/config.info
index 53bd8aaea..cabdd0ab2 100644
--- a/custom/config.info
+++ b/custom/config.info
@@ -5,3 +5,5 @@ height=Height of file editor window,3,Default (20 chars)
 wrap=File editor wrap mode,1,-Default (Soft),hard-Hard,off-Off
 columns=Columns to display commands in,1,2-2,1-1
 sort=Sort commands by,1,desc-Command name,html-Description,-Command ordering
+params_file=Treat default values starting with / as file to read?,1,1-Yes,0-No
+params_cmd=Treat default values ending with | as command to run?,1,1-Yes,0-No
diff --git a/custom/custom-lib.pl b/custom/custom-lib.pl
index 2b05d88a7..523969dd8 100755
--- a/custom/custom-lib.pl
+++ b/custom/custom-lib.pl
@@ -537,24 +537,39 @@ sub show_parameter_input
 {
 local ($a, $form) = @_;
 local $n = $a->{'name'};
+local $v = $a->{'opts'};
+if ($a->{'type'} != 9 && $a->{'type'} != 12) {
+	if ($v =~ /^"(.*)"$/ || $v =~ /^'(.*)'$/) {
+		# Quoted default
+		$v = $1;
+		}
+	elsif ($v =~ /^\// && $config{'params_file'}) {
+		# File to read
+		$v = &read_file_contents($v);
+		}
+	elsif ($v =~ /^(.*)\s*\|$/ && $config{'params_cmd'}) {
+		# Command to run
+		$v = &backquote_command("$1 2>/dev/null </dev/null");
+		}
+	}
 if ($a->{'type'} == 0) {
-	return &ui_textbox($n, undef, 30);
+	return &ui_textbox($n, $v, 30);
 	}
 elsif ($a->{'type'} == 1 || $a->{'type'} == 2) {
-	return &ui_user_textbox($n, undef, $form);
+	return &ui_user_textbox($n, $v, $form);
 	}
 elsif ($a->{'type'} == 3 || $a->{'type'} == 4) {
-	return &ui_group_textbox($n, undef, $form);
+	return &ui_group_textbox($n, $v, $form);
 	}
 elsif ($a->{'type'} == 5 || $a->{'type'} == 6) {
-	return &ui_textbox($n, $a->{'opts'}, 30)." ".
+	return &ui_textbox($n, $v, 30)." ".
 	       &file_chooser_button($n, $a->{'type'}-5, $form);
 	}
 elsif ($a->{'type'} == 7) {
-	return &ui_yesno_radio($n, 0);
+	return &ui_yesno_radio($n, $v =~ /true|yes|1/ ? 1 : 0);
 	}
 elsif ($a->{'type'} == 8) {
-	return &ui_password($n, undef, 30);
+	return &ui_password($n, $v, 30);
 	}
 elsif ($a->{'type'} == 9) {
 	return &ui_select($n, undef, [ &read_opts_file($a->{'opts'}) ]);
@@ -563,7 +578,7 @@ elsif ($a->{'type'} == 10) {
 	return &ui_upload($n, 30);
 	}
 elsif ($a->{'type'} == 11) {
-	return &ui_textarea($n, undef, 4, 30);
+	return &ui_textarea($n, $v, 4, 30);
 	}
 elsif ($a->{'type'} == 12) {
 	return &ui_select($n, undef, [ &read_opts_file($a->{'opts'}) ],