Index: openacs-4/packages/acs-admin/www/monitor.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-admin/www/monitor.tcl,v
diff -u -r1.3.2.2 -r1.3.2.3
--- openacs-4/packages/acs-admin/www/monitor.tcl	27 Nov 2016 12:19:35 -0000	1.3.2.2
+++ openacs-4/packages/acs-admin/www/monitor.tcl	20 Jun 2017 19:34:23 -0000	1.3.2.3
@@ -65,10 +65,13 @@
 
 set distinct [array size ip_p]
 
-# run standard Unix uptime command to get load average (crude measure of 
-# system health)
+# run standard GNU uptime command to get load average (crude measure
+# of system health).
+if {[set uptime [util::which uptime]] eq ""} {
+    error "'uptime' command not found on the system"
+}
 
-if {[catch { set uptime_output [exec /usr/bin/uptime] } errmsg]} {
+if {[catch { set uptime_output [exec $uptime] } errmsg]} {
    # whoops something wrong with uptime (check path)
    set uptime_output "ERROR running uptime, check path in script"
 }
Index: openacs-4/packages/acs-admin/www/apm/version-generate-diffs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-admin/www/apm/Attic/version-generate-diffs.tcl,v
diff -u -r1.4.2.2 -r1.4.2.3
--- openacs-4/packages/acs-admin/www/apm/version-generate-diffs.tcl	10 Sep 2015 08:21:04 -0000	1.4.2.2
+++ openacs-4/packages/acs-admin/www/apm/version-generate-diffs.tcl	20 Jun 2017 19:34:23 -0000	1.4.2.3
@@ -39,7 +39,10 @@
 	continue
     }
 
-    set cmd [list exec /usr/bin/diff]
+    if {[set diff [util::which diff]] eq ""} {
+        error "'diff' command not found on the system"
+    }
+    set cmd [list exec $diff]
     if { $context_p } {
 	lappend cmd "-c"
     }