diff --git a/README.md b/README.md
index f2a6729..0d13511 100644
--- a/README.md
+++ b/README.md
@@ -35,16 +35,14 @@ A group of commands that will allow you to:
 ```
 vivosnap.rb prepare uri-list [class_list_file] [VIVO_homepage_URL] {uri_list_file {REPLACE}}
 ```
-**NOT IMPLEMENTED**  
 Create a list of URIs. You provide a file with class URIs, and a URL for VIVO. 
 The tool will make requests of VIVOs ListRDF API, and write the results. 
 If uri_list_file already exists, you must specify REPLACE. If uri_list_file is not provided,
 the URI list goes to stdout, along with the summary info. 
 
 ```
-vivosnap.rb prepare session-list [uri_list_file] [account_email] [account_password] [session_list_file]
+prepare session-list [uri_list_file] {account_email:account_password} {session_list_file {REPLACE}}
 ```
-**NOT IMPLEMENTED**  
 Create a session list. 
 You provide a file of URIs, and the tool will generate the URLs needed to fetch the profile pages for those URIs.
 If you want a login on each session, provide the email address and password of the desired login account.
diff --git a/cmd_prepare_session_list/cmd_prepare_session_list.rb b/cmd_prepare_session_list/cmd_prepare_session_list.rb
index a1f1ce4..bbd4a4c 100644
--- a/cmd_prepare_session_list/cmd_prepare_session_list.rb
+++ b/cmd_prepare_session_list/cmd_prepare_session_list.rb
@@ -1,10 +1,94 @@
+=begin
+--------------------------------------------------------------------------------
+
+Create a session list.
+You provide a file of URIs, and the tool will generate the URLs needed to fetch
+the profile pages for those URIs.
+
+If you want a login on each session, provide the email address and password of
+the desired login account.
+
+if credentials are provided, each session looks like this:
+LOGIN email password ==> display?uri=uri_from_list
+otherwise, like this:
+display?uri=uri_from_list
+
+--------------------------------------------------------------------------------
+
+vivosnap.rb prepare session-list [uri_list_file] [account_email:account_password] {session_list_file {REPLACE}}
+
+--------------------------------------------------------------------------------
+=end
+
 class CmdPrepareSessionList
+  USAGE = 'prepare session-list [uri_list_file] {account_email:account_password} {session_list_file {REPLACE}}'
   def initialize(args)
-    bogus "CmdPrepareSessionList.initialize NOT IMPLEMENTED"
+    @args = args
+    @replace = true && args.delete('REPLACE')
+
+    complain("usage: #{USAGE}") unless (1..3).include? args.size
+
+    @uri_list_file = args[0]
+    complain("'#{@uri_list_file}' does not exist.") unless File.exist?(@uri_list_file)
+
+    case args.size
+    when 1
+      @credentials = nil
+      @session_list_file = nil
+    when 2
+      if args[1].include?(':')
+        @credentials = args[1].split(':')
+        @session_list_file = nil
+      else
+        @credentials = nil
+        @session_list_file = args[1]
+      end
+    else
+      @credentials = args[1].split(':')
+      @session_list_file = args[2]
+    end
+
+    complain("usage: #{USAGE}") if @credentials && @credentials.size != 2
+
+    if (@session_list_file)
+      complain("#{@session_list_file} already exists. Specify REPLACE to overwrite.") if File.exist?(@session_list_file) unless @replace
+      @output = File.open(@session_list_file, 'w')
+    else
+      @output = $stdout
+    end
   end
-  
+
   def run()
-    bogus "CmdPrepareSessionList.run NOT IMPLEMENTED"
+    write_heading
+    @counter = 0
+
+    File.open(@uri_list_file) do |f|
+      f.each_line do |uri|
+        next if uri.start_with?('#') || uri.strip.empty?
+        @output.puts(make_session(uri))
+        @counter += 1
+      end
+    end
+
+    write_report
+  end
+
+  def write_heading()
+    @output.puts "#"
+    @output.puts "# prepare session-list #{@args.join(' ')}"
+    @output.puts "# #{Time.now.strftime('%Y-%m-%d %H:%M:%S')}"
+    @output.puts "#"
+  end
+
+  def make_session(uri)
+    session = @credentials ? "LOGIN %s %s ==> " % @credentials : ''
+    session += "display?uri=#{uri}"
+  end
+
+  def write_report()
+    report = "#\n# wrote #{@counter} session lines.\n#"
+    @output.puts(report)
+    puts(report) if @output != $stdout
   end
 end
 
diff --git a/cmd_prepare_uri_list/cmd_prepare_uri_list.rb b/cmd_prepare_uri_list/cmd_prepare_uri_list.rb
index 406a688..f14c273 100644
--- a/cmd_prepare_uri_list/cmd_prepare_uri_list.rb
+++ b/cmd_prepare_uri_list/cmd_prepare_uri_list.rb
@@ -13,7 +13,9 @@ class CmdPrepareUriList
   USAGE = 'prepare uri-list [class_list_file] [VIVO_homepage_URL] {uri_list_file {REPLACE}}'
   def initialize(args)
     @args = args
-    complain("usage: #{USAGE}") unless (2..4).include? args.size
+
+    @replace = args.delete('REPLACE')
+    complain("usage: #{USAGE}") unless (2..3).include? args.size
 
     @class_list_file = args[0]
     complain("'#{@class_list_file}' does not exist.") unless File.exist?(@class_list_file)
@@ -31,7 +33,7 @@ def initialize(args)
     @uri_list_file = args[2]
 
     if @uri_list_file
-      complain("'#{@uri_list_file}' already exists. Specify REPLACE to replace it.") if File.exist?(@uri_list_file) unless 'REPLACE' == args[3]
+      complain("'#{@uri_list_file}' already exists. Specify REPLACE to replace it.") if File.exist?(@uri_list_file) unless @replace
       @output = File.open(@uri_list_file, 'w')
     else
       @output = $stdout
diff --git a/common.rb b/common.rb
index 8c41c35..2bc4059 100644
--- a/common.rb
+++ b/common.rb
@@ -19,6 +19,30 @@ def complain(message)
   raise UserInputError.new(message)
 end
 
+#
+# Record stdout and stderr, even while they are being displayed.
+#
+class MultiIO < IO
+  def initialize(*targets)
+     @targets = targets
+  end
+
+  def write(*args)
+    @targets.each {|t| t.write(*args)}
+  end
+
+  def flush()
+    @targets.each(&:flush)
+  end
+
+  def close
+    @targets.each(&:close)
+  end
+end
+
+$stdout = MultiIO.new(STDOUT, File.open(File.expand_path('~/vivosnap.stdout'), "w"))
+$stderr = MultiIO.new(STDERR, File.open(File.expand_path('~/vivosnap.stderr'), "w"))
+
 require_relative 'cmd_prepare_uri_list/cmd_prepare_uri_list'
 require_relative 'cmd_prepare_session_list/cmd_prepare_session_list'
 require_relative 'cmd_prepare_self_editor_account/cmd_prepare_self_editor_account'