diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
index 963b18ed85..1192faa6ae 100644
--- a/doc/src/sgml/runtime.sgml
+++ b/doc/src/sgml/runtime.sgml
@@ -1258,11 +1258,12 @@ default:\
     <itemizedlist>
      <listitem>
       <para>
-      On <productname>Linux</productname>
-      <filename>/proc/sys/fs/file-max</filename> determines the
-      maximum number of open files that the kernel will support.  It can
-      be changed by writing a different number into the file or by
-      adding an assignment in <filename>/etc/sysctl.conf</filename>.
+      On <productname>Linux</productname> the kernel parameter
+      <varname>fs.file-max</varname> determines the maximum number of open
+      files that the kernel will support.  It can be changed with
+      <literal>sysctl -w fs.file-max=<replaceable>N</replaceable></literal>.
+      To make the setting persist across reboots, add an assignment
+      in <filename>/etc/sysctl.conf</filename>.
       The maximum limit of files per process is fixed at the time the
       kernel is compiled; see
       <filename>/usr/src/linux/Documentation/proc.txt</filename> for
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 8a038d1b2a..1664fcee2a 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -4891,7 +4891,7 @@ SubPostmasterMain(int argc, char *argv[])
 	 * If testing EXEC_BACKEND on Linux, you should run this as root before
 	 * starting the postmaster:
 	 *
-	 * echo 0 >/proc/sys/kernel/randomize_va_space
+	 * sysctl -w kernel.randomize_va_space=0
 	 *
 	 * This prevents using randomized stack and code addresses that cause the
 	 * child process's memory map to be different from the parent's, making it