deal with not-0 return value of kpsewhich -var-value for not defined keys

git-svn-id: svn://tug.org/texlive/trunk@18585 c570f23f-e606-0410-a88d-b1316a301751

1 files changed, 12 insertions, 4 deletions

diff --git a/Master/texmf/scripts/texlive/tlmgr.pl b/Master/texmf/scripts/texlive/tlmgr.pl
index 3204c42d9d1..b6521c88779 100755
--- a/Master/texmf/scripts/texlive/tlmgr.pl
+++ b/Master/texmf/scripts/texlive/tlmgr.pl
@@ -4099,11 +4099,19 @@ sub action_conf {
           info("$key not defined in $arg config file\n");
           if ($arg eq "texmf") {
             # for the case of texmf.cnf we check the default value
-            chomp (my $defval = `kpsewhich -var-value $key`);
-            if (defined($defval)) {
-              info("Default value for $key is $defval\n");
-            } else {
+            # kpsewhich returns 1 if the value is not set, and 0 if it is
+            # so to distinguish between a key that is not defined and
+            # a key that is defined but to the empty string we have to
+            # call first with system and check the return value, and then
+            # if the return value is true get the actual value with backticks!!
+            # what a pain
+            my $retval = system("kpsewhich -var-value $key >" 
+                                  . (win32() ? "nul" : "/dev/null"));
+            if ($retval != 0) {
               info("No default value for $key is known.\n");
+            } else {
+              chomp (my $defval = `kpsewhich -var-value $key`);
+              info("Default value for $key is $defval\n");
             }
           }
         }