Don't hardcode /usr/bin/env for Unix.

PR: 17642


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@274375 13f79535-47bb-0310-9956-ffa450edef68

WHATSNEW

@@ -79,6 +79,9 @@ Fixed bugs:
 * <antlr> will now recompile your grammar if the supergrammar has
   changed.  Bugzilla Report 12691.
 
+* <property env> will now work on Unices with /bin/env instead of
+  /usr/bin/env.  Bugzilla Report 17642.
+
 Other changes:
 --------------
 * Shipped XML parser is now Xerces 2.4.0
@@ -145,7 +148,7 @@ Other changes:
 * <tarfileset> has a new dirmode attribute to specify the permissions
   for directories.
 
-* <fixcrlf>'s eol attribute now also understand "mac", "unix" and "dos".
+* <fixcrlf>'s eol attribute now also understands "mac", "unix" and "dos".
 
 * <classfileset> now picks up dependencies of the form MyClass.class. This
   works for the code generated by the Sun java compiler. It may not work for

src/main/org/apache/tools/ant/taskdefs/Execute.java

@@ -229,19 +229,23 @@ public class Execute {
                 String[] cmd = {"command.com", "/c", "set" };
                 return cmd;
             }
-        } else if (Os.isFamily("z/os")) {
-            String[] cmd = {"/bin/env"};
-            return cmd;
-        } else if (Os.isFamily("tandem")) {
-//            String[] cmd = {"/bin/sh -c env"};
-            String[] cmd = {"/bin/env"};
-            return cmd;
-        } else if (Os.isFamily("unix")) {
-            // Generic UNIX
-            // Alternatively one could use: /bin/sh -c env
-            String[] cmd = {"/usr/bin/env"};
+        } else if (Os.isFamily("z/os") || Os.isFamily("tandem") 
+                   || Os.isFamily("unix")) {
+            // On most systems one could use: /bin/sh -c env
+
+            // Some systems have /bin/env, others /usr/bin/env, just try
+            String[] cmd = new String[1];
+            if (new File("/bin/env").canRead()) {
+                cmd[0] = "/bin/env";
+            } else if (new File("/usr/bin/env").canRead()) {
+                cmd[0] = "/usr/bin/env";
+            } else {
+                // rely on PATH
+                cmd[0] = "env";
+            }
             return cmd;
         } else if (Os.isFamily("netware") || Os.isFamily("os/400")) {
+            // rely on PATH
             String[] cmd = {"env"};
             return cmd;
         } else {