cowsay: cowthink

fix #462638

pkgs/by-name/co/cowsay/package.nix

@@ -33,6 +33,17 @@ stdenv.mkDerivation (finalAttrs: {
   postInstall = ''
     wrapProgram $out/bin/cowsay \
       --suffix COWPATH : $out/share/cowsay/cows
+
+    # Replace the cowthink symlink with a Perl wrapper that sets $0 correctly
+    # This is necessary because exec -a doesn't work for Perl scripts
+    rm $out/bin/cowthink
+    cat > $out/bin/cowthink << EOF
+    #!/usr/bin/env perl
+    \$0 = "cowthink";
+    \$ENV{COWPATH} = "\$ENV{COWPATH}" . (\$ENV{COWPATH} ? ":" : "") . "$out/share/cowsay/cows";
+    do "$out/bin/.cowsay-wrapped";
+    EOF
+    chmod +x $out/bin/cowthink
   '';
 
   passthru = {