DOS/Linux shell

.gitignore

@@ -0,0 +1 @@
+tmp/

README.md

@@ -108,6 +108,17 @@ You can influence runtime behaviour with environment variables. Set them either
 
 `dos-shell` also writes a managed `~/.dosemu/dosemurc` (marked with `# Managed by dos-shell…`) when it needs to enforce CPU or audio fallbacks. Delete the file to restore defaults; it is regenerated on demand.
 
+### Podman / Docker exec entrypoints
+
+`dos-shell` remains the default login shell for `dosuser`, so a plain `podman exec -it dos-env dos-shell` (or `docker exec`) drops you straight into the DOS session. When you need a regular Linux shell in the same running container, reuse the wrapper but append `--linux-shell`:
+
+```sh
+podman exec -it dos-env dos-shell --linux-shell        # interactive bash as dosuser
+podman exec -it dos-env dos-shell --linux-shell "ls"   # run a single command as dosuser
+```
+
+You can override which binary is used for the Linux side by setting `DOS_LINUX_SHELL` (defaults to `/bin/bash`).
+
 ## Environment Variables (Container / Compose)
 
 `compose.yml` exposes a few knobs. You can drop a `.env` file next to it to override the defaults.

scripts/dos-shell

@@ -15,6 +15,7 @@ ALLOW_MODE="${DOS_ALLOW_MODE:-all}"
 DEFAULT_DOS_USER="dosuser"
 INSTALL_SENTINEL_NAME=".svardos_installed"
 PRE_BOOT_HOOK="${DOS_PRE_BOOT_HOOK:-${ENV_DIR}/pre-boot.sh}"
+LINUX_SHELL="${DOS_LINUX_SHELL:-/bin/bash}"
 
 if [ "$(id -u)" -eq 0 ]; then
   DOS_USER="${DEFAULT_DOS_USER}"
@@ -29,6 +30,57 @@ if [ -z "${DOS_HOME}" ]; then
   exit 1
 fi
 
+shell_passthrough=0
+shell_payload=""
+
+if [ "${1:-}" = "--help" ]; then
+  cat <<'EOF'
+Usage: dos-shell [--linux-shell [command]]
+
+Default invocation boots the DOS environment via dosemu.
+Use --linux-shell to open the underlying Linux shell instead.
+EOF
+  exit 0
+fi
+
+if [ "${1:-}" = "--linux-shell" ]; then
+  shift
+  shell_passthrough=1
+  if [ $# -gt 0 ]; then
+    shell_payload="$*"
+  fi
+fi
+
+if [ "${shell_passthrough}" -eq 0 ] && [ -n "${SSH_ORIGINAL_COMMAND:-}" ]; then
+  case "${SSH_ORIGINAL_COMMAND}" in
+    linux-shell)
+      shell_passthrough=1
+      shell_payload=""
+      ;;
+    linux-shell[[:space:]]*)
+      shell_passthrough=1
+      shell_payload="${SSH_ORIGINAL_COMMAND#linux-shell}"
+      shell_payload="${shell_payload#"${shell_payload%%[![:space:]]*}"}"
+      ;;
+  esac
+fi
+
+if [ "${shell_passthrough}" -eq 1 ]; then
+  if [ "$(id -u)" -eq 0 ]; then
+    if [ -n "${shell_payload}" ]; then
+      exec runuser -u "${DOS_USER}" -- "${LINUX_SHELL}" -lc "${shell_payload}"
+    else
+      exec runuser -u "${DOS_USER}" -- "${LINUX_SHELL}" -l
+    fi
+  else
+    if [ -n "${shell_payload}" ]; then
+      exec "${LINUX_SHELL}" -lc "${shell_payload}"
+    else
+      exec "${LINUX_SHELL}" -l
+    fi
+  fi
+fi
+
 DOSEMU_DIR="${DOS_HOME}/.dosemu"
 C_DRIVE="${DOSEMU_DIR}/drive_c"
 INSTALL_SENTINEL_PATH="${DOSEMU_DIR}/${INSTALL_SENTINEL_NAME}"