add nicer + tmuxbash

pkgs/nicer.nix

@@ -0,0 +1,28 @@
+{
+  coreutils,
+  writeShellApplication,
+}:
+writeShellApplication {
+  name = "nicer";
+  text = ''
+    f=$(${coreutils}/bin/mktemp)
+    trap '${coreutils}/bin/rm -f "$f"' EXIT
+    ${coreutils}/bin/env > "$f"
+    systemd-run \
+        --user \
+        --same-dir \
+        --slice nicer \
+        --nice=19 \
+        --property CPUSchedulingPolicy=idle \
+        --property IOSchedulingClass=idle \
+        --property IOSchedulingPriority=7 \
+        --pty \
+        --pipe \
+        --wait \
+        --collect \
+        --quiet \
+        --property EnvironmentFile="$f" \
+        --service-type=exec \
+        -- "$@"
+  '';
+}

pkgs/tmuxbash.nix

@@ -0,0 +1,13 @@
+{
+  tmux,
+  bash,
+  writeShellApplication,
+  ...
+}:
+writeShellApplication {
+  name = "tmuxbash";
+  text = ''
+    ${tmux}/bin/tmux
+    ${bash}/bin/bash
+  '';
+}