l: allow piping into sxiv

lass/2configs/baseX.nix

@@ -79,9 +79,7 @@ in {
     powertop
     rxvt-unicode
     sshvnc
-    (pkgs.writers.writeDashBin "sxiv" ''
+    sxiv
-      ${pkgs.nsxiv}/bin/nsxiv "$@"
-    '')
     nsxiv
     taskwarrior
     termite

lass/5pkgs/sxiv/default.nix

@@ -0,0 +1,27 @@
+{ nsxiv, writers }:
+
+writers.writeDashBin "sxiv" ''
+  set -efu
+  tmpfile="''${TMPDIR:-/tmp}/nsxiv_pipe_$$"
+  trap 'rm -f -- $tmpfile' EXIT
+
+  if [ "$#" -eq 0 ]; then
+    if [ -t 0 ]; then
+      echo "sxiv: No arguments provided" >&2; exit 1
+    else
+      # Consume stdin and put it in the temporal file
+      cat > "$tmpfile"
+    fi
+  fi
+
+  for arg in "$@"; do
+    # if it's a pipe then drain it to $tmpfile
+    [ -p "$arg" ] && cat "$arg" > "$tmpfile"
+  done
+
+  if [ -s "$tmpfile" ]; then
+    ${nsxiv}/bin/nsxiv -q "$@" "$tmpfile" # -q to silence warnings
+  else
+    ${nsxiv}/bin/nsxiv "$@" # fallback
+  fi
+''