Switched from 'system' calls to 'exec' to increase compatibility.

fedora_repository.install

@@ -68,8 +68,8 @@ function fedora_repository_requirements($phase) {
 
     // Check for ImageMagick
     $requirements['fedora-imagemagick']['title'] = t("ImageMagick convert in \$PATH");
-    system('which -s convert', $res);
-    if ($res != 0) {
+    $result = exec('convert');
+    if (!$result) {
       $requirements['fedora-imagemagick']['value'] = t('Not in $PATH');
       $requirements['fedora-imagemagick']['description'] = t('Islandora will not be able to create thumbnails. Ensure that <a href="www.imagemagick.org/">ImageMagick</a> is installed and the convert command is executable by the web server user.');
       $requirements['fedora-imagemagick']['severity'] = REQUIREMENT_WARNING;
@@ -80,8 +80,8 @@ function fedora_repository_requirements($phase) {
     }
 
     $requirements['fedora-kakadu']['title'] = 'Kakadu kdu_compress in $PATH';
-    system('which -s kdu_compress', $kdu_res);
-    if ($kdu_res != 0) {
+    $kdu_res = exec('kdu_compress -v');
+    if (!$kdu_res) {
       $requirements['fedora-kakadu']['value'] = ('Not in $PATH');
       $requirements['fedora-kakadu']['description'] = t('Islandora cannot convert TIFF image files to JPEG2000 format. Ensure <a href="http://www.kakadusoftware.com/">Kakadu</a> is installed and the kdu_compress command is executable by the web server user.');
       $requirements['fedora-kakadu']['severity'] = REQUIREMENT_WARNING;