diff --git a/app/build.gradle b/app/build.gradle
index 9cd39b1..5867471 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -44,6 +44,9 @@ android {
     targetCompatibility 1.8
     sourceCompatibility 1.8
   }
+  kotlinOptions {
+    freeCompilerArgs = ["-Xallow-result-return-type"]
+  }
 }
 
 dependencies {
diff --git a/app/src/main/java/io/neoterm/component/colorscheme/ColorSchemeComponent.kt b/app/src/main/java/io/neoterm/component/colorscheme/ColorSchemeComponent.kt
index 4e2875f..f855c5f 100644
--- a/app/src/main/java/io/neoterm/component/colorscheme/ColorSchemeComponent.kt
+++ b/app/src/main/java/io/neoterm/component/colorscheme/ColorSchemeComponent.kt
@@ -9,10 +9,9 @@ import io.neoterm.frontend.component.ComponentManager
 import io.neoterm.frontend.component.helper.ConfigFileBasedComponent
 import io.neoterm.frontend.config.NeoPreference
 import io.neoterm.frontend.config.NeoTermPath
-import io.neoterm.frontend.logging.NLog
 import io.neoterm.frontend.terminal.TerminalView
 import io.neoterm.frontend.terminal.extrakey.ExtraKeysView
-import io.neoterm.utils.AssetsUtils
+import io.neoterm.utils.extractAssetsDir
 import java.io.File
 import java.nio.file.Files
 
@@ -103,15 +102,8 @@ class ColorSchemeComponent : ConfigFileBasedComponent<NeoColorScheme>(NeoTermPat
     setCurrentColorScheme(color.colorName)
   }
 
-  private fun extractDefaultColor(context: Context): Boolean {
-    try {
-      AssetsUtils.extractAssetsDir(context, "colors", baseDir)
-      return true
-    } catch (e: Exception) {
-      NLog.e("ColorScheme", "Failed to extract default colors: ${e.localizedMessage}")
-      return false
-    }
-  }
+  private fun extractDefaultColor(context: Context) =
+    kotlin.runCatching { context.extractAssetsDir("colors", baseDir) }.isSuccess
 
   fun saveColorScheme(colorScheme: NeoColorScheme) {
     val colorFile = colorFile(colorScheme.colorName)
diff --git a/app/src/main/java/io/neoterm/component/extrakey/ExtraKeyComponent.kt b/app/src/main/java/io/neoterm/component/extrakey/ExtraKeyComponent.kt
index 9a7fc41..36ed3a7 100644
--- a/app/src/main/java/io/neoterm/component/extrakey/ExtraKeyComponent.kt
+++ b/app/src/main/java/io/neoterm/component/extrakey/ExtraKeyComponent.kt
@@ -7,7 +7,7 @@ import io.neoterm.frontend.component.helper.ConfigFileBasedComponent
 import io.neoterm.frontend.config.NeoTermPath
 import io.neoterm.frontend.logging.NLog
 import io.neoterm.frontend.terminal.extrakey.ExtraKeysView
-import io.neoterm.utils.AssetsUtils
+import io.neoterm.utils.extractAssetsDir
 import java.io.File
 
 /**
@@ -52,7 +52,7 @@ class ExtraKeyComponent : ConfigFileBasedComponent<NeoExtraKey>(NeoTermPath.EKS_
 
   private fun extractDefaultConfig(context: Context) {
     try {
-      AssetsUtils.extractAssetsDir(context, "eks", baseDir)
+      context.extractAssetsDir("eks", baseDir)
     } catch (e: Exception) {
       NLog.e("ExtraKey", "Failed to extract configure: ${e.localizedMessage}")
     }
diff --git a/app/src/main/java/io/neoterm/component/font/FontComponent.kt b/app/src/main/java/io/neoterm/component/font/FontComponent.kt
index 02a4a33..3c9d337 100644
--- a/app/src/main/java/io/neoterm/component/font/FontComponent.kt
+++ b/app/src/main/java/io/neoterm/component/font/FontComponent.kt
@@ -10,7 +10,7 @@ import io.neoterm.frontend.config.NeoPreference
 import io.neoterm.frontend.config.NeoTermPath
 import io.neoterm.frontend.terminal.TerminalView
 import io.neoterm.frontend.terminal.extrakey.ExtraKeysView
-import io.neoterm.utils.AssetsUtils
+import io.neoterm.utils.extractAssetsDir
 import java.io.File
 
 /**
@@ -90,7 +90,7 @@ class FontComponent : NeoComponent {
 
   private fun extractDefaultFont(context: Context): Boolean {
     try {
-      AssetsUtils.extractAssetsDir(context, "fonts", NeoTermPath.FONT_PATH)
+      context.extractAssetsDir( "fonts", NeoTermPath.FONT_PATH)
       return true
     } catch (e: Exception) {
       return false
diff --git a/app/src/main/java/io/neoterm/component/userscript/UserScriptComponent.kt b/app/src/main/java/io/neoterm/component/userscript/UserScriptComponent.kt
index 9cee684..a15eaa0 100644
--- a/app/src/main/java/io/neoterm/component/userscript/UserScriptComponent.kt
+++ b/app/src/main/java/io/neoterm/component/userscript/UserScriptComponent.kt
@@ -6,7 +6,7 @@ import io.neoterm.App
 import io.neoterm.frontend.component.NeoComponent
 import io.neoterm.frontend.config.NeoTermPath
 import io.neoterm.frontend.logging.NLog
-import io.neoterm.utils.AssetsUtils
+import io.neoterm.utils.extractAssetsDir
 import java.io.File
 
 /**
@@ -28,7 +28,7 @@ class UserScriptComponent : NeoComponent {
 
   private fun extractDefaultScript(context: Context): Boolean {
     try {
-      AssetsUtils.extractAssetsDir(context, "scripts", NeoTermPath.USER_SCRIPT_PATH)
+      context.extractAssetsDir( "scripts", NeoTermPath.USER_SCRIPT_PATH)
       File(NeoTermPath.USER_SCRIPT_PATH)
         .listFiles().forEach {
           Os.chmod(it.absolutePath, 448 /*Dec of 0700*/)
diff --git a/app/src/main/java/io/neoterm/frontend/floating/TerminalDialog.kt b/app/src/main/java/io/neoterm/frontend/floating/TerminalDialog.kt
index 9833bc5..918f569 100644
--- a/app/src/main/java/io/neoterm/frontend/floating/TerminalDialog.kt
+++ b/app/src/main/java/io/neoterm/frontend/floating/TerminalDialog.kt
@@ -9,7 +9,7 @@ import io.neoterm.frontend.session.shell.ShellParameter
 import io.neoterm.frontend.session.shell.ShellTermSession
 import io.neoterm.frontend.session.shell.client.BasicSessionCallback
 import io.neoterm.frontend.session.shell.client.BasicViewClient
-import io.neoterm.utils.TerminalUtils
+import io.neoterm.utils.Terminals
 
 /**
  * @author kiva
@@ -56,7 +56,7 @@ class TerminalDialog(val context: Context) {
       .arguments(arguments)
       .callback(terminalSessionCallback)
       .systemShell(false)
-    terminalSession = TerminalUtils.createSession(context, parameter)
+    terminalSession = Terminals.createSession(context, parameter)
     if (terminalSession is ShellTermSession) {
       (terminalSession as ShellTermSession).exitPrompt = context.getString(R.string.process_exit_prompt_press_back)
     }
diff --git a/app/src/main/java/io/neoterm/frontend/floating/WindowTermView.kt b/app/src/main/java/io/neoterm/frontend/floating/WindowTermView.kt
index c07b22e..b05b835 100644
--- a/app/src/main/java/io/neoterm/frontend/floating/WindowTermView.kt
+++ b/app/src/main/java/io/neoterm/frontend/floating/WindowTermView.kt
@@ -8,7 +8,7 @@ import io.neoterm.R
 import io.neoterm.backend.TerminalSession
 import io.neoterm.frontend.terminal.TerminalView
 import io.neoterm.frontend.terminal.TerminalViewClient
-import io.neoterm.utils.TerminalUtils
+import io.neoterm.utils.Terminals
 
 /**
  * @author kiva
@@ -21,7 +21,7 @@ class WindowTermView(val context: Context) {
     private set
 
   init {
-    TerminalUtils.setupTerminalView(terminalView)
+    Terminals.setupTerminalView(terminalView)
   }
 
   fun setTerminalViewClient(terminalViewClient: TerminalViewClient?) {
diff --git a/app/src/main/java/io/neoterm/services/NeoTermService.kt b/app/src/main/java/io/neoterm/services/NeoTermService.kt
index c9d0472..c25b492 100644
--- a/app/src/main/java/io/neoterm/services/NeoTermService.kt
+++ b/app/src/main/java/io/neoterm/services/NeoTermService.kt
@@ -19,7 +19,7 @@ import io.neoterm.frontend.session.shell.ShellParameter
 import io.neoterm.frontend.session.xorg.XParameter
 import io.neoterm.frontend.session.xorg.XSession
 import io.neoterm.ui.term.NeoTermActivity
-import io.neoterm.utils.TerminalUtils
+import io.neoterm.utils.Terminals
 
 
 /**
@@ -94,7 +94,7 @@ class NeoTermService : Service() {
   }
 
   fun createXSession(activity: AppCompatActivity, parameter: XParameter): XSession {
-    val session = TerminalUtils.createSession(activity, parameter)
+    val session = Terminals.createSession(activity, parameter)
     mXSessions.add(session)
     updateNotification()
     return session
@@ -112,7 +112,7 @@ class NeoTermService : Service() {
   private fun createOrFindSession(parameter: ShellParameter): TerminalSession {
     if (parameter.willCreateNewSession()) {
       NLog.d("createOrFindSession: creating new session")
-      val session = TerminalUtils.createSession(this, parameter)
+      val session = Terminals.createSession(this, parameter)
       mTerminalSessions.add(session)
       return session
     }
diff --git a/app/src/main/java/io/neoterm/ui/customize/BaseCustomizeActivity.kt b/app/src/main/java/io/neoterm/ui/customize/BaseCustomizeActivity.kt
index afb1010..0e21a34 100644
--- a/app/src/main/java/io/neoterm/ui/customize/BaseCustomizeActivity.kt
+++ b/app/src/main/java/io/neoterm/ui/customize/BaseCustomizeActivity.kt
@@ -12,7 +12,7 @@ import io.neoterm.frontend.session.shell.client.BasicSessionCallback
 import io.neoterm.frontend.session.shell.client.BasicViewClient
 import io.neoterm.frontend.terminal.TerminalView
 import io.neoterm.frontend.terminal.extrakey.ExtraKeysView
-import io.neoterm.utils.TerminalUtils
+import io.neoterm.utils.Terminals
 
 /**
  * @author kiva
@@ -36,8 +36,8 @@ open class BaseCustomizeActivity : AppCompatActivity() {
     extraKeysView = findViewById(R.id.custom_extra_keys)
     viewClient = BasicViewClient(terminalView)
     sessionCallback = BasicSessionCallback(terminalView)
-    TerminalUtils.setupTerminalView(terminalView, viewClient)
-    TerminalUtils.setupExtraKeysView(extraKeysView)
+    Terminals.setupTerminalView(terminalView, viewClient)
+    Terminals.setupExtraKeysView(extraKeysView)
 
     val script = resources.getStringArray(R.array.custom_preview_script_colors)
     val parameter = ShellParameter()
@@ -46,7 +46,7 @@ open class BaseCustomizeActivity : AppCompatActivity() {
       .callback(sessionCallback)
       .systemShell(false)
 
-    session = TerminalUtils.createSession(this, parameter)
+    session = Terminals.createSession(this, parameter)
     terminalView.attachSession(session)
   }
 
diff --git a/app/src/main/java/io/neoterm/ui/customize/ColorSchemeActivity.kt b/app/src/main/java/io/neoterm/ui/customize/ColorSchemeActivity.kt
index 714215e..d824943 100644
--- a/app/src/main/java/io/neoterm/ui/customize/ColorSchemeActivity.kt
+++ b/app/src/main/java/io/neoterm/ui/customize/ColorSchemeActivity.kt
@@ -24,7 +24,7 @@ import io.neoterm.frontend.component.ComponentManager
 import io.neoterm.frontend.terminal.TerminalView
 import io.neoterm.ui.customize.adapter.ColorItemAdapter
 import io.neoterm.ui.customize.model.ColorItem
-import io.neoterm.utils.TerminalUtils
+import io.neoterm.utils.Terminals
 
 
 /**
@@ -51,7 +51,7 @@ class ColorSchemeActivity : BaseCustomizeActivity() {
     editingColorScheme.colorName = ""
 
     val terminalView = findViewById<TerminalView>(R.id.terminal_view)
-    TerminalUtils.setupTerminalView(terminalView, null)
+    Terminals.setupTerminalView(terminalView, null)
 
     adapter = ColorItemAdapter(this, editingColorScheme, COMPARATOR, object : ColorItemAdapter.Listener {
       override fun onModelClicked(model: ColorItem) {
diff --git a/app/src/main/java/io/neoterm/ui/customize/CustomizeActivity.kt b/app/src/main/java/io/neoterm/ui/customize/CustomizeActivity.kt
index 45d1c2d..1d45e2e 100644
--- a/app/src/main/java/io/neoterm/ui/customize/CustomizeActivity.kt
+++ b/app/src/main/java/io/neoterm/ui/customize/CustomizeActivity.kt
@@ -13,7 +13,7 @@ import io.neoterm.component.colorscheme.ColorSchemeComponent
 import io.neoterm.component.font.FontComponent
 import io.neoterm.frontend.component.ComponentManager
 import io.neoterm.frontend.config.NeoTermPath
-import io.neoterm.utils.MediaUtils
+import io.neoterm.utils.getPathOfMediaUri
 import java.io.File
 import java.nio.file.Files
 import java.nio.file.Paths
@@ -114,7 +114,7 @@ class CustomizeActivity : BaseCustomizeActivity() {
 
   override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
     if (resultCode == RESULT_OK && data != null) {
-      val selected = MediaUtils.getPath(this, data.data)
+      val selected = this.getPathOfMediaUri( data.data)
       if (selected != null && selected.isNotEmpty()) {
         when (requestCode) {
           REQUEST_SELECT_FONT -> installFont(selected)
diff --git a/app/src/main/java/io/neoterm/ui/pm/PackageManagerActivity.kt b/app/src/main/java/io/neoterm/ui/pm/PackageManagerActivity.kt
index 7016102..725e64b 100644
--- a/app/src/main/java/io/neoterm/ui/pm/PackageManagerActivity.kt
+++ b/app/src/main/java/io/neoterm/ui/pm/PackageManagerActivity.kt
@@ -25,7 +25,8 @@ import io.neoterm.frontend.floating.TerminalDialog
 import io.neoterm.ui.pm.adapter.PackageAdapter
 import io.neoterm.ui.pm.model.PackageModel
 import io.neoterm.ui.pm.utils.StringDistance
-import io.neoterm.utils.PackageUtils
+import io.neoterm.utils.runApt
+import java.util.*
 
 /**
  * @author kiva
@@ -178,67 +179,64 @@ class PackageManagerActivity : AppCompatActivity(), SearchView.OnQueryTextListen
     executeAptUpdate()
   }
 
-  private fun executeAptUpdate() {
-    PackageUtils.apt(this, "update", null, { exitStatus, dialog ->
-      if (exitStatus != 0) {
-        dialog.setTitle(getString(R.string.error))
-        return@apt
-      }
-      Toast.makeText(this, R.string.apt_update_ok, Toast.LENGTH_SHORT).show()
-      dialog.dismiss()
-      refreshPackageList()
-    })
+  private fun executeAptUpdate() = runApt("update", null) { exitStatus, dialog ->
+    if (exitStatus != 0) {
+      dialog.setTitle(getString(R.string.error))
+      return@runApt
+    }
+    Toast.makeText(this, R.string.apt_update_ok, Toast.LENGTH_SHORT).show()
+    dialog.dismiss()
+    refreshPackageList()
   }
 
-  private fun executeAptUpgrade() {
-    PackageUtils.apt(this, "update", null, { exitStatus, dialog ->
+  private fun executeAptUpgrade() = runApt("update", null) { exitStatus, dialog ->
+    if (exitStatus != 0) {
+      dialog.setTitle(getString(R.string.error))
+      return@runApt
+    }
+    dialog.dismiss()
+
+    runApt("upgrade", arrayOf("-y")) aptUpgrade@{ exitStatus, dialog ->
       if (exitStatus != 0) {
         dialog.setTitle(getString(R.string.error))
-        return@apt
+        return@aptUpgrade
       }
+      Toast.makeText(this, R.string.apt_upgrade_ok, Toast.LENGTH_SHORT).show()
       dialog.dismiss()
-
-      PackageUtils.apt(this, "upgrade", arrayOf("-y"), out@{ exitStatus, dialog ->
-        if (exitStatus != 0) {
-          dialog.setTitle(getString(R.string.error))
-          return@out
-        }
-        Toast.makeText(this, R.string.apt_upgrade_ok, Toast.LENGTH_SHORT).show()
-        dialog.dismiss()
-      })
-    })
+    }
   }
 
-  private fun refreshPackageList() {
+  private fun refreshPackageList() = Thread {
     models.clear()
-    Thread {
-      val pm = ComponentManager.getComponent<PackageComponent>()
-      val sourceFiles = SourceHelper.detectSourceFiles()
+    val pm = ComponentManager.getComponent<PackageComponent>()
+    val sourceFiles = SourceHelper.detectSourceFiles()
 
-      pm.clearPackages()
-      sourceFiles.forEach { pm.reloadPackages(it, false) }
-      pm.packages.values.mapTo(models, { PackageModel(it) })
+    pm.clearPackages()
+    sourceFiles.forEach { pm.reloadPackages(it, false) }
+    pm.packages.values.mapTo(models, { PackageModel(it) })
 
-      this@PackageManagerActivity.runOnUiThread {
-        adapter.edit()
-          .replaceAll(models)
-          .commit()
-        if (models.isEmpty()) {
-          Toast.makeText(this@PackageManagerActivity, R.string.package_list_empty, Toast.LENGTH_SHORT).show()
-          changeSource()
-        }
+    this@PackageManagerActivity.runOnUiThread {
+      adapter.edit()
+        .replaceAll(models)
+        .commit()
+      if (models.isEmpty()) {
+        Toast.makeText(this@PackageManagerActivity, R.string.package_list_empty, Toast.LENGTH_SHORT).show()
+        changeSource()
       }
-    }.start()
-  }
+    }
+  }.start()
 
   private fun sortDistance(
     models: List<PackageModel>, query: String,
     mapper: (NeoPackageInfo) -> String
   ): List<Pair<PackageModel, Int>> {
     return models
-      .map({
-        Pair(it, StringDistance.distance(mapper(it.packageInfo).toLowerCase(), query.toLowerCase()))
-      })
+      .map {
+        Pair(
+          it,
+          StringDistance.distance(mapper(it.packageInfo).toLowerCase(Locale.ROOT), query.toLowerCase(Locale.ROOT))
+        )
+      }
       .sortedWith(Comparator { l, r -> r.second.compareTo(l.second) })
       .toList()
   }
@@ -255,17 +253,10 @@ class PackageManagerActivity : AppCompatActivity(), SearchView.OnQueryTextListen
     return filteredModelList
   }
 
-  override fun onQueryTextSubmit(text: String?): Boolean {
-    return false
-  }
+  override fun onQueryTextSubmit(text: String?) = false
 
   override fun onQueryTextChange(text: String?): Boolean {
-    if (text != null) {
-      val filteredModelList = filter(models, text)
-      adapter.edit()
-        .replaceAll(filteredModelList)
-        .commit()
-    }
+    text?.let { adapter.edit().replaceAll(filter(models, it)).commit() }
     return true
   }
 
diff --git a/app/src/main/java/io/neoterm/ui/pm/model/PackageModel.kt b/app/src/main/java/io/neoterm/ui/pm/model/PackageModel.kt
index 5fb6909..a52704e 100644
--- a/app/src/main/java/io/neoterm/ui/pm/model/PackageModel.kt
+++ b/app/src/main/java/io/neoterm/ui/pm/model/PackageModel.kt
@@ -5,7 +5,7 @@ import com.github.wrdlbrnft.sortedlistadapter.SortedListAdapter
 import io.neoterm.R
 
 import io.neoterm.component.pm.NeoPackageInfo
-import io.neoterm.utils.FileUtils
+import io.neoterm.utils.formatSizeInKB
 
 /**
  * @author kiva
@@ -28,7 +28,7 @@ class PackageModel(val packageInfo: NeoPackageInfo) : SortedListAdapter.ViewMode
       R.string.package_details,
       packageInfo.packageName, packageInfo.version,
       packageInfo.dependenciesString,
-      FileUtils.formatSizeInKB(packageInfo.installedSizeInBytes),
+      packageInfo.installedSizeInBytes.formatSizeInKB(),
       packageInfo.description, packageInfo.homePage
     )
   }
diff --git a/app/src/main/java/io/neoterm/ui/settings/GeneralSettingsActivity.kt b/app/src/main/java/io/neoterm/ui/settings/GeneralSettingsActivity.kt
index 889d27d..361f167 100644
--- a/app/src/main/java/io/neoterm/ui/settings/GeneralSettingsActivity.kt
+++ b/app/src/main/java/io/neoterm/ui/settings/GeneralSettingsActivity.kt
@@ -5,7 +5,7 @@ import android.view.MenuItem
 import androidx.appcompat.app.AlertDialog
 import io.neoterm.R
 import io.neoterm.frontend.config.NeoPreference
-import io.neoterm.utils.PackageUtils
+import io.neoterm.utils.runApt
 
 /**
  * @author kiva
@@ -39,16 +39,14 @@ class GeneralSettingsActivity : BasePreferenceActivity() {
     AlertDialog.Builder(this)
       .setTitle(getString(R.string.shell_not_found, shellName))
       .setMessage(R.string.shell_not_found_message)
-      .setPositiveButton(R.string.install, { _, _ ->
-        PackageUtils.apt(this, "install", arrayOf("-y", shellName), { exitStatus, dialog ->
+      .setPositiveButton(R.string.install) { _, _ ->
+        runApt("install", arrayOf("-y", shellName)) { exitStatus, dialog ->
           if (exitStatus == 0) {
             dialog.dismiss()
             postChangeShell(shellName)
-          } else {
-            dialog.setTitle(getString(R.string.error))
-          }
-        })
-      })
+          } else dialog.setTitle(getString(R.string.error))
+        }
+      }
       .setNegativeButton(android.R.string.no, null)
       .setOnDismissListener {
         postChangeShell(currentShell)
diff --git a/app/src/main/java/io/neoterm/ui/setup/SetupActivity.kt b/app/src/main/java/io/neoterm/ui/setup/SetupActivity.kt
index 4134d14..982bf01 100644
--- a/app/src/main/java/io/neoterm/ui/setup/SetupActivity.kt
+++ b/app/src/main/java/io/neoterm/ui/setup/SetupActivity.kt
@@ -19,8 +19,8 @@ import io.neoterm.setup.SourceConnection
 import io.neoterm.setup.connections.BackupFileConnection
 import io.neoterm.setup.connections.LocalFileConnection
 import io.neoterm.setup.connections.NetworkConnection
-import io.neoterm.utils.MediaUtils
-import io.neoterm.utils.PackageUtils
+import io.neoterm.utils.getPathOfMediaUri
+import io.neoterm.utils.runApt
 import java.io.File
 
 
@@ -32,7 +32,6 @@ class SetupActivity : AppCompatActivity(), View.OnClickListener, ResultListener
     private const val REQUEST_SELECT_PARAMETER = 520;
   }
 
-  private var aptUpdated = false
   private var setupParameter = ""
   private var setupParameterUri: Uri? = null
 
@@ -83,8 +82,7 @@ class SetupActivity : AppCompatActivity(), View.OnClickListener, ResultListener
   override fun onActivityResult(requestCode: Int, resultCode: Int, resultData: Intent?) {
     if (requestCode == REQUEST_SELECT_PARAMETER && resultCode == RESULT_OK) {
       if (resultData != null) {
-        setupParameterUri = resultData.data
-        val path = MediaUtils.getPath(this, setupParameterUri!!)
+        val path = this.getPathOfMediaUri(resultData.data)
         findViewById<EditText>(R.id.setup_source_parameter).setText(path)
         return
       }
@@ -236,26 +234,11 @@ class SetupActivity : AppCompatActivity(), View.OnClickListener, ResultListener
     }
   }
 
-  private fun executeAptUpdate() {
-    PackageUtils.apt(this, "update", null) { exitStatus, dialog ->
-      if (exitStatus == 0) {
-        dialog.dismiss()
-        aptUpdated = true
-        executeAptUpgrade()
-      } else {
-        dialog.setTitle(getString(R.string.error))
-      }
-    }
-  }
+  private fun executeAptUpdate() = runApt("update")
+    .onSuccess { executeAptUpgrade() }
+    .onFailure { Toast.makeText(this, R.string.error, Toast.LENGTH_SHORT).show() }
 
-  private fun executeAptUpgrade() {
-    PackageUtils.apt(this, "upgrade", arrayOf("-y")) { exitStatus, dialog ->
-      if (exitStatus == 0) {
-        dialog.dismiss()
-        finish()
-      } else {
-        dialog.setTitle(getString(R.string.error))
-      }
-    }
-  }
-}
\ No newline at end of file
+  private fun executeAptUpgrade() = runApt("upgrade", "-y")
+    .onSuccess { finish() }
+    .onFailure { Toast.makeText(this, R.string.error, Toast.LENGTH_SHORT).show() }
+}
diff --git a/app/src/main/java/io/neoterm/ui/term/NeoTermActivity.kt b/app/src/main/java/io/neoterm/ui/term/NeoTermActivity.kt
index c733cc2..9962804 100644
--- a/app/src/main/java/io/neoterm/ui/term/NeoTermActivity.kt
+++ b/app/src/main/java/io/neoterm/ui/term/NeoTermActivity.kt
@@ -777,9 +777,7 @@ class NeoTermActivity : AppCompatActivity(), ServiceConnection, SharedPreference
     }
 
     val rangedInt = RangedInt(tabSwitcher.selectedTabIndex, (0 until tabSwitcher.count))
-    val nextIndex = if (switchSessionEvent.toNext)
-      rangedInt.increaseOne()
-    else rangedInt.decreaseOne()
+    val nextIndex = if (switchSessionEvent.toNext) rangedInt.inc() else rangedInt.dec()
     if (!tabSwitcher.isSwitcherShown) {
       tabSwitcher.showSwitcher()
     }
diff --git a/app/src/main/java/io/neoterm/ui/term/NeoTermRemoteInterface.kt b/app/src/main/java/io/neoterm/ui/term/NeoTermRemoteInterface.kt
index 205693d..4a96dbe 100644
--- a/app/src/main/java/io/neoterm/ui/term/NeoTermRemoteInterface.kt
+++ b/app/src/main/java/io/neoterm/ui/term/NeoTermRemoteInterface.kt
@@ -21,8 +21,8 @@ import io.neoterm.frontend.config.NeoPreference
 import io.neoterm.frontend.session.shell.ShellParameter
 import io.neoterm.frontend.session.shell.client.TermSessionCallback
 import io.neoterm.services.NeoTermService
-import io.neoterm.utils.MediaUtils
-import io.neoterm.utils.TerminalUtils
+import io.neoterm.utils.Terminals
+import io.neoterm.utils.getPathOfMediaUri
 import java.io.File
 
 /**
@@ -67,13 +67,10 @@ class NeoTermRemoteInterface : AppCompatActivity(), ServiceConnection {
     handleIntent()
   }
 
-  private fun handleIntent() {
-    val className = intent.component.className.substringAfterLast('.')
-    when (className) {
-      "TermHere" -> handleTermHere()
-      "UserScript" -> handleUserScript()
-      else -> handleNormal()
-    }
+  private fun handleIntent() = when (intent.component?.className?.substringAfterLast('.')) {
+    "TermHere" -> handleTermHere()
+    "UserScript" -> handleUserScript()
+    else -> handleNormal()
   }
 
   private fun handleNormal() {
@@ -98,12 +95,12 @@ class NeoTermRemoteInterface : AppCompatActivity(), ServiceConnection {
 
   private fun handleTermHere() {
     if (intent.hasExtra(Intent.EXTRA_STREAM)) {
-      val extra = intent.extras.get(Intent.EXTRA_STREAM)
+      val extra = intent.extras?.get(Intent.EXTRA_STREAM)
       if (extra is Uri) {
-        val path = MediaUtils.getPath(this, extra)
+        val path = this.getPathOfMediaUri(extra)
         val file = File(path)
         val dirPath = if (file.isDirectory) path else file.parent
-        val command = "cd " + TerminalUtils.escapeString(dirPath)
+        val command = "cd " + Terminals.escapeString(dirPath)
         openTerm(command, null)
       }
       finish()
@@ -128,23 +125,23 @@ class NeoTermRemoteInterface : AppCompatActivity(), ServiceConnection {
 
     if (intent.hasExtra(Intent.EXTRA_STREAM)) {
       // action send
-      val extra = intent.extras.get(Intent.EXTRA_STREAM)
+      val extra = intent.extras?.get(Intent.EXTRA_STREAM)
 
       when (extra) {
         is ArrayList<*> -> {
           extra.takeWhile { it is Uri }
             .mapTo(filesToHandle) {
               val uri = it as Uri
-              File(MediaUtils.getPath(this, uri)).absolutePath
+              File(this.getPathOfMediaUri(uri)).absolutePath
             }
         }
         is Uri -> {
-          filesToHandle.add(File(MediaUtils.getPath(this, extra)).absolutePath)
+          filesToHandle.add(File(this.getPathOfMediaUri(extra)).absolutePath)
         }
       }
     } else if (intent.data != null) {
       // action view
-      filesToHandle.add(File(intent.data.path).absolutePath)
+      filesToHandle.add(File(intent.data?.path).absolutePath)
     }
 
     if (filesToHandle.isNotEmpty()) {
diff --git a/app/src/main/java/io/neoterm/ui/term/tab/NeoTabDecorator.kt b/app/src/main/java/io/neoterm/ui/term/tab/NeoTabDecorator.kt
index 3cfee1d..3644998 100644
--- a/app/src/main/java/io/neoterm/ui/term/tab/NeoTabDecorator.kt
+++ b/app/src/main/java/io/neoterm/ui/term/tab/NeoTabDecorator.kt
@@ -23,7 +23,7 @@ import io.neoterm.frontend.session.shell.client.TermCompleteListener
 import io.neoterm.frontend.terminal.TerminalView
 import io.neoterm.frontend.terminal.extrakey.ExtraKeysView
 import io.neoterm.ui.term.NeoTermActivity
-import io.neoterm.utils.TerminalUtils
+import io.neoterm.utils.Terminals
 
 /**
  * @author kiva
@@ -43,8 +43,8 @@ class NeoTabDecorator(val context: NeoTermActivity) : TabSwitcherDecorator() {
         val view = inflater.inflate(R.layout.ui_term, parent, false)
         val terminalView = view.findViewById<TerminalView>(R.id.terminal_view)
         val extraKeysView = view.findViewById<ExtraKeysView>(R.id.extra_keys)
-        TerminalUtils.setupTerminalView(terminalView)
-        TerminalUtils.setupExtraKeysView(extraKeysView)
+        Terminals.setupTerminalView(terminalView)
+        Terminals.setupExtraKeysView(extraKeysView)
 
         val colorSchemeManager = ComponentManager.getComponent<ColorSchemeComponent>()
         colorSchemeManager.applyColorScheme(
diff --git a/app/src/main/java/io/neoterm/utils/AssetsUtils.kt b/app/src/main/java/io/neoterm/utils/AssetsUtils.kt
deleted file mode 100644
index c6aa699..0000000
--- a/app/src/main/java/io/neoterm/utils/AssetsUtils.kt
+++ /dev/null
@@ -1,23 +0,0 @@
-package io.neoterm.utils
-
-import android.content.Context
-import java.io.File
-import java.nio.file.Files
-
-/**
- * @author kiva
- */
-object AssetsUtils {
-  fun extractAssetsDir(context: Context, dirName: String, extractDir: String) {
-    val assets = context.assets
-    assets.list(dirName)?.let {
-      it.map { File(extractDir, it) }
-        .takeWhile { !it.exists() }
-        .forEach { file ->
-          assets.open("$dirName/${file.name}").use {
-            kotlin.runCatching { Files.copy(it, file.toPath()) }
-          }
-        }
-    }
-  }
-}
\ No newline at end of file
diff --git a/app/src/main/java/io/neoterm/utils/FileUtils.kt b/app/src/main/java/io/neoterm/utils/FileUtils.kt
deleted file mode 100644
index 94ea8eb..0000000
--- a/app/src/main/java/io/neoterm/utils/FileUtils.kt
+++ /dev/null
@@ -1,26 +0,0 @@
-package io.neoterm.utils
-
-import java.text.DecimalFormat
-
-/**
- * @author kiva
- */
-object FileUtils {
-  fun formatSizeInKB(size: Long): String {
-    val decimalFormat = DecimalFormat("####.00");
-    if (size < 1024) {
-      return "$size KB"
-    } else if (size < 1024 * 1024) {
-      val parsedSize: Float = size / 1024f
-      return decimalFormat.format(parsedSize) + " MB"
-    } else if (size < 1024 * 1024 * 1024) {
-      val parsedSize: Float = size / 1024f / 1024f
-      return decimalFormat.format(parsedSize) + " GB"
-    } else if (size < 1024L * 1024 * 1024 * 1024) {
-      val parsedSize: Float = size / 1024f / 1024f / 1024f
-      return decimalFormat.format(parsedSize) + " TB"
-    } else {
-      return "$size KB"
-    }
-  }
-}
\ No newline at end of file
diff --git a/app/src/main/java/io/neoterm/utils/MediaUtils.kt b/app/src/main/java/io/neoterm/utils/MediaUtils.kt
deleted file mode 100644
index 1c0cf32..0000000
--- a/app/src/main/java/io/neoterm/utils/MediaUtils.kt
+++ /dev/null
@@ -1,141 +0,0 @@
-package io.neoterm.utils
-
-import android.annotation.SuppressLint
-import android.content.ContentUris
-import android.content.Context
-import android.database.Cursor
-import android.net.Uri
-import android.os.Build
-import android.os.Environment
-import android.provider.DocumentsContract
-import android.provider.MediaStore
-
-/**
- * @author kiva
- */
-
-object MediaUtils {
-  /**
-   * Get a file path from a Uri. This will get the the path for Storage Access
-   * Framework Documents, as well as the _data field for the MediaStore and
-   * other file-based ContentProviders.
-
-   * @param context The context.
-   * *
-   * @param uri     The Uri to query.
-   */
-  @SuppressLint("ObsoleteSdkInt")
-  fun getPath(context: Context, uri: Uri?): String? {
-    uri ?: return null
-    val isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT
-    // DocumentProvider
-    if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
-      // ExternalStorageProvider
-      if (isExternalStorageDocument(uri)) {
-        val docId = DocumentsContract.getDocumentId(uri)
-        val split = docId.split(":".toRegex()).dropLastWhile { it.isEmpty() }.toTypedArray()
-        val type = split[0]
-
-        if ("primary".equals(type, ignoreCase = true)) {
-          return Environment.getExternalStorageDirectory().toString() + "/" + split[1]
-        }
-
-        // Temporary workaround for non-primary volumes
-        return "/storage/$type/${split[1]}"
-
-      } else if (isDownloadsDocument(uri)) {
-        val id = DocumentsContract.getDocumentId(uri)
-        val contentUri = ContentUris.withAppendedId(
-          Uri.parse("content://downloads/public_downloads"), java.lang.Long.valueOf(id)!!
-        )
-
-        return getDataColumn(context, contentUri, null, null)
-      } else if (isMediaDocument(uri)) {
-        val docId = DocumentsContract.getDocumentId(uri)
-        val split = docId.split(":".toRegex()).dropLastWhile { it.isEmpty() }.toTypedArray()
-
-        val contentUri = when (split[0]) {
-          "image" -> MediaStore.Images.Media.EXTERNAL_CONTENT_URI
-          "video" -> MediaStore.Video.Media.EXTERNAL_CONTENT_URI
-          "audio" -> MediaStore.Audio.Media.EXTERNAL_CONTENT_URI
-          else -> null
-        }
-
-        val selection = "_id=?"
-        val selectionArgs = arrayOf(split[1])
-
-        return getDataColumn(context, contentUri!!, selection, selectionArgs)
-      }
-    } else if ("content".equals(uri.scheme, ignoreCase = true)) {
-      return getDataColumn(context, uri, null, null)
-    } else if ("file".equals(uri.scheme, ignoreCase = true)) {
-      return uri.path
-    }
-
-    return null
-  }
-
-  /**
-   * Get the value of the data column for this Uri. This is useful for
-   * MediaStore Uris, and other file-based ContentProviders.
-
-   * @param context       The context.
-   * *
-   * @param uri           The Uri to query.
-   * *
-   * @param selection     (Optional) Filter used in the query.
-   * *
-   * @param selectionArgs (Optional) Selection arguments used in the query.
-   * *
-   * @return The value of the _data column, which is typically a file path.
-   */
-  private fun getDataColumn(
-    context: Context, uri: Uri, selection: String?,
-    selectionArgs: Array<String>?
-  ): String? {
-
-    var cursor: Cursor? = null
-    val column = "_data"
-    val projection = arrayOf(column)
-
-    try {
-      cursor = context.contentResolver.query(uri, projection, selection, selectionArgs, null)
-      if (cursor != null && cursor.moveToFirst()) {
-        val column_index = cursor.getColumnIndexOrThrow(column)
-        return cursor.getString(column_index)
-      }
-    } finally {
-      if (cursor != null)
-        cursor.close()
-    }
-    return null
-  }
-
-
-  /**
-   * @param uri The Uri to check.
-   * *
-   * @return Whether the Uri authority is ExternalStorageProvider.
-   */
-  private fun isExternalStorageDocument(uri: Uri): Boolean {
-    return "com.android.externalstorage.documents" == uri.authority
-  }
-
-  /**
-   * @param uri The Uri to check.
-   * *
-   * @return Whether the Uri authority is DownloadsProvider.
-   */
-  private fun isDownloadsDocument(uri: Uri): Boolean {
-    return "com.android.providers.downloads.documents" == uri.authority
-  }
-
-  /**
-   * @param uri The Uri to check.
-   * *
-   * @return Whether the Uri authority is MediaProvider.
-   */
-  private fun isMediaDocument(uri: Uri): Boolean {
-    return "com.android.providers.media.documents" == uri.authority
-  }
-}
diff --git a/app/src/main/java/io/neoterm/utils/PackageUtils.kt b/app/src/main/java/io/neoterm/utils/PackageUtils.kt
deleted file mode 100644
index 00e97cd..0000000
--- a/app/src/main/java/io/neoterm/utils/PackageUtils.kt
+++ /dev/null
@@ -1,28 +0,0 @@
-package io.neoterm.utils
-
-import android.content.Context
-import io.neoterm.backend.TerminalSession
-import io.neoterm.frontend.config.NeoTermPath
-import io.neoterm.frontend.floating.TerminalDialog
-
-/**
- * @author kiva
- */
-object PackageUtils {
-  fun apt(context: Context, subCommand: String, extraArgs: Array<String>?, callback: (Int, TerminalDialog) -> Unit) {
-    val argArray =
-      if (extraArgs != null) arrayOf(NeoTermPath.APT_BIN_PATH, subCommand, *extraArgs)
-      else arrayOf(NeoTermPath.APT_BIN_PATH, subCommand)
-
-    TerminalDialog(context)
-      .onFinish(object : TerminalDialog.SessionFinishedCallback {
-        override fun onSessionFinished(dialog: TerminalDialog, finishedSession: TerminalSession?) {
-          val exit = finishedSession?.exitStatus ?: 1
-          callback(exit, dialog)
-        }
-      })
-      .imeEnabled(true)
-      .execute(NeoTermPath.APT_BIN_PATH, argArray)
-      .show("apt $subCommand")
-  }
-}
\ No newline at end of file
diff --git a/app/src/main/java/io/neoterm/utils/RangedInt.kt b/app/src/main/java/io/neoterm/utils/RangedInt.kt
deleted file mode 100644
index 611bfe2..0000000
--- a/app/src/main/java/io/neoterm/utils/RangedInt.kt
+++ /dev/null
@@ -1,22 +0,0 @@
-package io.neoterm.utils
-
-/**
- * @author kiva
- */
-class RangedInt(val number: Int, val range: IntRange) {
-  fun increaseOne(): Int {
-    var result = number + 1
-    if (result > range.last) {
-      result = 0
-    }
-    return result
-  }
-
-  fun decreaseOne(): Int {
-    var result = number - 1
-    if (result < 0) {
-      result = range.last
-    }
-    return result
-  }
-}
\ No newline at end of file
diff --git a/app/src/main/java/io/neoterm/utils/TerminalUtils.kt b/app/src/main/java/io/neoterm/utils/Terminals.kt
similarity index 98%
rename from app/src/main/java/io/neoterm/utils/TerminalUtils.kt
rename to app/src/main/java/io/neoterm/utils/Terminals.kt
index bc8c690..2a44c87 100644
--- a/app/src/main/java/io/neoterm/utils/TerminalUtils.kt
+++ b/app/src/main/java/io/neoterm/utils/Terminals.kt
@@ -17,7 +17,7 @@ import io.neoterm.frontend.terminal.extrakey.ExtraKeysView
 /**
  * @author kiva
  */
-object TerminalUtils {
+object Terminals {
   fun setupTerminalView(terminalView: TerminalView?, terminalViewClient: TerminalViewClient? = null) {
     terminalView?.textSize = NeoPreference.getFontSize();
 
diff --git a/app/src/main/java/io/neoterm/utils/utils.kt b/app/src/main/java/io/neoterm/utils/utils.kt
new file mode 100644
index 0000000..73d8015
--- /dev/null
+++ b/app/src/main/java/io/neoterm/utils/utils.kt
@@ -0,0 +1,135 @@
+package io.neoterm.utils
+
+import android.content.ContentUris
+import android.content.Context
+import android.net.Uri
+import android.os.Environment
+import android.provider.DocumentsContract
+import android.provider.MediaStore
+import io.neoterm.backend.TerminalSession
+import io.neoterm.frontend.config.NeoTermPath
+import io.neoterm.frontend.floating.TerminalDialog
+import java.io.File
+import java.nio.file.Files
+import java.text.DecimalFormat
+
+class RangedInt(private val number: Int, private val range: IntRange) {
+  fun inc() = (number + 1).takeIf { range.contains(it) } ?: 0
+  fun dec() = (number - 1).takeIf { range.contains(it) } ?: range.last
+}
+
+fun Long.formatSizeInKB(): String {
+  val decimalFormat = DecimalFormat("####.00");
+  if (this < 1024) {
+    return "$this KB"
+  } else if (this < 1024 * 1024) {
+    val parsedSize: Float = this / 1024f
+    return decimalFormat.format(parsedSize) + " MB"
+  } else if (this < 1024 * 1024 * 1024) {
+    val parsedSize: Float = this / 1024f / 1024f
+    return decimalFormat.format(parsedSize) + " GB"
+  } else if (this < 1024L * 1024 * 1024 * 1024) {
+    val parsedSize: Float = this / 1024f / 1024f / 1024f
+    return decimalFormat.format(parsedSize) + " TB"
+  } else {
+    return "$this KB"
+  }
+}
+
+fun Context.extractAssetsDir(dirName: String, extractDir: String) {
+  val assets = this.assets
+  assets.list(dirName)?.let {
+    it.map { File(extractDir, it) }
+      .takeWhile { !it.exists() }
+      .forEach { file ->
+        assets.open("$dirName/${file.name}").use {
+          kotlin.runCatching { Files.copy(it, file.toPath()) }
+        }
+      }
+  }
+}
+
+fun Context.runApt(subCommand: String, vararg extraArgs: String): Result<TerminalDialog> = runAsyncCatching {
+  val args = arrayOf(NeoTermPath.APT_BIN_PATH, subCommand, *extraArgs)
+  TerminalDialog(this)
+    .onFinish(object : TerminalDialog.SessionFinishedCallback {
+      override fun onSessionFinished(dialog: TerminalDialog, finishedSession: TerminalSession?) {
+        val exit = finishedSession?.exitStatus ?: 1
+        if (exit == 0) {
+          dialog.dismiss()
+          throw SuccessResult(dialog)
+        }
+        else throw RuntimeException()
+      }
+    })
+    .imeEnabled(true)
+    .execute(NeoTermPath.APT_BIN_PATH, args)
+    .show("apt $subCommand")
+}
+
+/**
+ * Get a file path from a Uri. This will get the the path for Storage Access
+ * Framework Documents, as well as the _data field for the MediaStore and
+ * other file-based ContentProviders.
+ * @param context The context.
+ * @param inUri     The Uri to query.
+ */
+fun Context.getPathOfMediaUri(inUri: Uri?) = inUri?.let {
+  when {
+    "content".equals(it.scheme, ignoreCase = true) -> getDataColumn(this, it, null, null)
+    "file".equals(it.scheme, ignoreCase = true) -> it.path
+    DocumentsContract.isDocumentUri(this, it) -> this.getPathOfDocumentUri(it)
+    else -> null
+  }
+}
+
+private fun Context.getPathOfDocumentUri(uri: Uri) = if (isExternalStorageDocument(uri)) {
+  val docId = DocumentsContract.getDocumentId(uri)
+  val split = docId.split(":".toRegex()).dropLastWhile { it.isEmpty() }.toTypedArray()
+  val type = split[0]
+  if ("primary".equals(type, ignoreCase = true)) Environment.getExternalStorageDirectory().toString() + "/" + split[1]
+  else "/storage/$type/${split[1]}"  // Temporary workaround for non-primary volumes
+} else if (isDownloadsDocument(uri)) {
+  val id = DocumentsContract.getDocumentId(uri)
+  val contentUri = ContentUris.withAppendedId(
+    Uri.parse("content://downloads/public_downloads"), java.lang.Long.valueOf(id)
+  )
+  getDataColumn(this, contentUri, null, null)
+} else if (isMediaDocument(uri)) {
+  val docId = DocumentsContract.getDocumentId(uri)
+  val split = docId.split(":".toRegex()).dropLastWhile { it.isEmpty() }.toTypedArray()
+  val contentUri = when (split[0]) {
+    "image" -> MediaStore.Images.Media.EXTERNAL_CONTENT_URI
+    "video" -> MediaStore.Video.Media.EXTERNAL_CONTENT_URI
+    "audio" -> MediaStore.Audio.Media.EXTERNAL_CONTENT_URI
+    else -> null
+  }
+  getDataColumn(this, contentUri!!, "_id=?", arrayOf(split[1]))
+} else null
+
+/**
+ * Get the value of the data column for this Uri
+ */
+private fun getDataColumn(context: Context, uri: Uri, selection: String?, selectionArgs: Array<String>?) =
+  context.contentResolver.query(uri, arrayOf("_data"), selection, selectionArgs, null)?.use {
+    if (it.moveToFirst()) {
+      val columnIndex = it.getColumnIndex("_data").takeIf { it != -1 } ?: return@use null
+      it.getString(columnIndex)
+    } else null
+  }
+
+private fun isExternalStorageDocument(uri: Uri) = "com.android.externalstorage.documents" == uri.authority
+private fun isDownloadsDocument(uri: Uri) = "com.android.providers.downloads.documents" == uri.authority
+private fun isMediaDocument(uri: Uri) = "com.android.providers.media.documents" == uri.authority
+
+data class SuccessResult(val data: Any) : RuntimeException()
+
+inline fun <reified R> runAsyncCatching(block: () -> Unit): Result<R> = try {
+  block()
+  Result.failure(IllegalStateException())
+} catch (s: SuccessResult) {
+  if (s.data is R) Result.success(s.data)
+  else Result.failure(ClassCastException())
+} catch (e: Throwable) {
+  Result.failure(e)
+}