source code comments and docs: fix typos, language, Markdown layout

- fix a/an before noun
- fix loose -> lose
- fix "the the"
- fix lets -> let's
- fix Markdown layout
- fix a few typos
- remove unnecessary text in troubleshooting.md

Signed-off-by: Erik Sjölund <erik.sjolund@gmail.com>

cmd/podman-wslkerninst/main.go

@@ -29,7 +29,7 @@ const KernelWarning = "WSL Kernel installation did not complete successfully. "
 
 func setupLogging(name string) (*eventlog.Log, error) {
 	// Reuse the Built-in .NET Runtime Source so that we do not
-	// have to provide a messaage table and modify the system
+	// have to provide a message table and modify the system
 	// event configuration
 	log, err := eventlog.Open(".NET Runtime")
 	if err != nil {

cmd/podman/common/completion.go

@@ -339,7 +339,7 @@ func getPathCompletion(root string, toComplete string) ([]string, cobra.ShellCom
 	for _, e := range entries {
 		if strings.HasPrefix(e.Name(), base) {
 			suf := ""
-			// When the entry is an directory we add the "/" as suffix and do not want to add space
+			// When the entry is a directory we add the "/" as suffix and do not want to add space
 			// to match normal shell completion behavior.
 			// Just inc counter again to fake more than one entry in this case and thus get no space.
 			if e.IsDir() {
@@ -383,7 +383,7 @@ func validCurrentCmdLine(cmd *cobra.Command, args []string, toComplete string) b
 	if err := cmd.Args(cmd, append(args, toComplete)); err != nil {
 		// Special case if we use ExactArgs(2) or MinimumNArgs(2),
 		// They will error if we try to complete the first arg.
-		// Lets try to parse the common error and compare if we have less args than
+		// Let's try to parse the common error and compare if we have less args than
 		// required. In this case we are fine and should provide completion.
 
 		// Clean the err msg so we can parse it with fmt.Sscanf
@@ -698,7 +698,7 @@ func AutocompleteCpCommand(cmd *cobra.Command, args []string, toComplete string)
 	if len(args) < 2 {
 		if i := strings.IndexByte(toComplete, ':'); i > -1 {
 			// Looks like the user already set the container.
-			// Lets mount it and provide path completion for files in the container.
+			// Let's mount it and provide path completion for files in the container.
 			engine, err := setupContainerEngine(cmd)
 			if err != nil {
 				cobra.CompErrorln(err.Error())
@@ -1328,9 +1328,9 @@ func getMethodNames(f reflect.Value, prefix string) []formatSuggestion {
 		if kind == reflect.Struct || kind == reflect.Map {
 			suffix = "."
 		}
-		// From a template users POV it is not important when the use a struct field or method.
+		// From a template user's POV it is not important whether they use a struct field or method.
 		// They only notice the difference when the function requires arguments.
-		// So lets be nice and let the user know that this method requires arguments via the help text.
+		// So let's be nice and let the user know that this method requires arguments via the help text.
 		// Note since this is actually a method on a type the first argument is always fix so we should skip it.
 		num := method.Func.Type().NumIn() - 1
 		if num > 0 {

cmd/podman/containers/ps.go

@@ -368,7 +368,7 @@ func (l psReporter) Status() string {
 
 		// strings.Title is deprecated since go 1.18
 		// However for our use case it is still fine. The recommended replacement
-		// is adding about 400kb binary size so lets keep using this for now.
+		// is adding about 400kb binary size so let's keep using this for now.
 		//nolint:staticcheck
 		state = strings.Title(l.ListContainer.State)
 	}

cmd/podman/kube/play.go

@@ -279,7 +279,7 @@ func play(cmd *cobra.Command, args []string) error {
 	ch := make(chan os.Signal, 1)
 	var teardownReader *bytes.Reader
 	if playOptions.Wait {
-		// Stop the the shutdown signal handler so we can actually clean up after a SIGTERM or interrupt
+		// Stop the shutdown signal handler so we can actually clean up after a SIGTERM or interrupt
 		if err := shutdown.Stop(); err != nil && err != shutdown.ErrNotStarted {
 			return err
 		}

cmd/podman/registry/registry.go

@@ -63,7 +63,7 @@ func ContainerEngine() entities.ContainerEngine {
 	return containerEngine
 }
 
-// NewContainerEngine is a wrapper for building an ContainerEngine to be used for PreRunE functions
+// NewContainerEngine is a wrapper for building a ContainerEngine to be used for PreRunE functions
 func NewContainerEngine(cmd *cobra.Command, args []string) (entities.ContainerEngine, error) {
 	if containerEngine == nil {
 		podmanOptions.FlagSet = cmd.Flags()

cmd/podman/root.go

@@ -233,7 +233,7 @@ func persistentPreRunE(cmd *cobra.Command, args []string) error {
 	// Special case if command is hidden completion command ("__complete","__completeNoDesc")
 	// Since __completeNoDesc is an alias the cm.Name is always __complete
 	if cmd.Name() == cobra.ShellCompRequestCmd {
-		// Parse the cli arguments after the the completion cmd (always called as second argument)
+		// Parse the cli arguments after the completion cmd (always called as second argument)
 		// This ensures that the --url, --identity and --connection flags are properly set
 		compCmd, _, err := cmd.Root().Traverse(os.Args[2:])
 		if err != nil {

cmd/podman/validate/args.go

@@ -51,7 +51,7 @@ func IDOrLatestArgs(cmd *cobra.Command, args []string) error {
 }
 
 // CheckAllLatestAndCIDFile checks that --all and --latest are used correctly for containers and pods
-// If idFileFlag is set is set, also checks for the --cidfile or --pod-id-file flag.
+// If idFileFlag is set, also checks for the --cidfile or --pod-id-file flag.
 // Note: this has been deprecated, use CheckAllLatestAndIDFile instead
 func CheckAllLatestAndCIDFile(c *cobra.Command, args []string, ignoreArgLen bool, cidfile bool) error {
 	return CheckAllLatestAndIDFile(c, args, ignoreArgLen, "cidfile")

cmd/quadlet/main.go

@@ -101,7 +101,7 @@ func Debugf(format string, a ...interface{}) {
 // and /etc/containers/systemd (for sysadmin files).
 // For user generators these can live in /etc/containers/systemd/users, /etc/containers/systemd/users/$UID, and $XDG_CONFIG_HOME/containers/systemd
 func getUnitDirs(rootless bool) []string {
-	// Allow overdiding source dir, this is mainly for the CI tests
+	// Allow overriding source dir, this is mainly for the CI tests
 	unitDirsEnv := os.Getenv("QUADLET_UNIT_DIRS")
 	if len(unitDirsEnv) > 0 {
 		return strings.Split(unitDirsEnv, ":")

docs/source/markdown/options/secret.md

@@ -21,7 +21,7 @@ Secret Options
 
 - `type=mount|env`    : How the secret is exposed to the container.
                         `mount` mounts the secret into the container as a file.
-                        `env` exposes the secret as a environment variable.
+                        `env` exposes the secret as an environment variable.
                         Defaults to `mount`.
 - `target=target`     : Target of secret.
                         For mounted secrets, this is the path to the secret inside the container.

docs/source/markdown/podman-manifest-exists.1.md

@@ -29,7 +29,7 @@ $ echo $?
 $
 ```
 
-Check if an manifest called `mylist` exists (the manifest list does not actually exist).
+Check if a manifest called `mylist` exists (the manifest list does not actually exist).
 ```
 $ podman manifest exists mylist
 $ echo $?

docs/source/markdown/podman-network-create.1.md

@@ -146,7 +146,7 @@ $ podman network create --subnet 192.168.33.0/24 --gateway 192.168.33.3 newnet
 newnet
 ```
 
-Create a network that uses a *192.168.55.0/24** subnet and has an IP address range of *192.168.55.129 - 192.168.55.254*.
+Create a network that uses a *192.168.55.0/24* subnet and has an IP address range of *192.168.55.129 - 192.168.55.254*.
 ```
 $ podman network create --subnet 192.168.55.0/24 --ip-range 192.168.55.128/25
 podman5

docs/tutorials/image_signing.md

@@ -161,7 +161,7 @@ accessed:
 127.0.0.1 - - [04/Mar/2020 11:18:21] "GET /alpine@sha256=e9b65ef660a3ff91d28cc50eba84f21798a6c5c39b4dd165047db49e84ae1fb9/signature-1 HTTP/1.1" 200 -
 ```
 
-As an counterpart example, if we specify the wrong key at `/tmp/key.gpg`:
+As a counterpart example, if we specify the wrong key at `/tmp/key.gpg`:
 
 ```bash
 gpg --output /tmp/key.gpg --armor --export mail@saschagrunert.de

libpod/boltdb_state.go

@@ -1115,7 +1115,7 @@ func (s *BoltState) GetNetworks(ctr *Container) (map[string]types.PerNetworkOpti
 						return nil
 					}
 
-					// lets ignore the error here there is nothing we can do
+					// let's ignore the error here there is nothing we can do
 					_ = netAliasesBkt.ForEach(func(alias, v []byte) error {
 						aliases = append(aliases, string(alias))
 						return nil

libpod/boltdb_state_internal.go

@@ -401,7 +401,7 @@ func (s *BoltState) getContainerConfigFromDB(id []byte, config *ContainerConfig,
 		config.ContainerNetworkConfig.PortMappings = ocicniPortsToNetTypesPorts(config.ContainerNetworkConfig.OldPortMappings)
 		// keep the OldPortMappings in case an user has to downgrade podman
 
-		// indicate the the config was modified and should be written back to the db when possible
+		// indicate that the config was modified and should be written back to the db when possible
 		config.rewrite = true
 	}
 
@@ -425,7 +425,7 @@ func (s *BoltState) getContainerStateDB(id []byte, ctr *Container, ctrsBkt *bolt
 		return fmt.Errorf("unmarshalling container %s state: %w", ctr.ID(), err)
 	}
 
-	// backwards compat, previously we used a extra bucket for the netns so try to get it from there
+	// backwards compat, previously we used an extra bucket for the netns so try to get it from there
 	netNSBytes := ctrToUpdate.Get(netNSKey)
 	if netNSBytes != nil && newState.NetNS == "" {
 		newState.NetNS = string(netNSBytes)

libpod/container_exec.go

@@ -20,7 +20,7 @@ import (
 
 // ExecConfig contains the configuration of an exec session
 type ExecConfig struct {
-	// Command the the command that will be invoked in the exec session.
+	// Command is the command that will be invoked in the exec session.
 	// Must not be empty.
 	Command []string `json:"command"`
 	// Terminal is whether the exec session will allocate a pseudoterminal.

libpod/container_internal_common.go

@@ -2371,7 +2371,7 @@ func (c *Container) groupEntry(groupname, gid string, list []string) string {
 //     /etc/passwd via AddCurrentUserPasswdEntry (though this does not trigger if
 //     the user in question already exists in /etc/passwd) or the UID to be added
 //     is 0).
-//  3. The user specified additional host user accounts to add the the /etc/passwd file
+//  3. The user specified additional host user accounts to add to the /etc/passwd file
 //
 // Returns password entry (as a string that can be appended to /etc/passwd) and
 // any error that occurred.

libpod/info.go

@@ -77,7 +77,7 @@ func (r *Runtime) info() (*define.Info, error) {
 
 // top-level "host" info
 func (r *Runtime) hostInfo() (*define.HostInfo, error) {
-	// lets say OS, arch, number of cpus, amount of memory, maybe os distribution/version, hostname, kernel version, uptime
+	// let's say OS, arch, number of cpus, amount of memory, maybe os distribution/version, hostname, kernel version, uptime
 	mi, err := system.ReadMemInfo()
 	if err != nil {
 		return nil, fmt.Errorf("reading memory info: %w", err)
@@ -195,7 +195,7 @@ func (r *Runtime) getContainerStoreInfo() (define.ContainerStore, error) {
 
 // top-level "store" info
 func (r *Runtime) storeInfo() (*define.StoreInfo, error) {
-	// lets say storage driver in use, number of images, number of containers
+	// let's say storage driver in use, number of images, number of containers
 	configFile, err := storage.DefaultConfigFile(rootless.IsRootless())
 	if err != nil {
 		return nil, err

libpod/kube.go

@@ -476,7 +476,7 @@ func (p *Pod) podWithContainers(ctx context.Context, containers []*Container, po
 				ctr.Ports = nil
 
 				// We add the original port declarations from the libpod infra container
-				// to the first kubernetes container description because otherwise we loose
+				// to the first kubernetes container description because otherwise we lose
 				// the original container/port bindings.
 				// Add the port configuration to the first regular container or the first
 				// init container if only init containers have been created in the pod.
@@ -903,7 +903,7 @@ func containerToV1Container(ctx context.Context, c *Container, getService bool)
 	return kubeContainer, kubeVolumes, &dns, annotations, nil
 }
 
-// portMappingToContainerPort takes an portmapping and converts
+// portMappingToContainerPort takes a portmapping and converts
 // it to a v1.ContainerPort format for kube output
 func portMappingToContainerPort(portMappings []types.PortMapping, getService bool) ([]v1.ContainerPort, error) {
 	containerPorts := make([]v1.ContainerPort, 0, len(portMappings))

libpod/logs/log.go

@@ -167,7 +167,7 @@ func getTailLog(path string, tail int) ([]*LogLine, error) {
 	return tailLog, nil
 }
 
-// getColor returns a ANSI escape code for color based on the colorID
+// getColor returns an ANSI escape code for color based on the colorID
 func getColor(colorID int64) string {
 	colors := map[int64]string{
 		0: "\033[37m", // Light Gray

libpod/networking_common.go

@@ -61,7 +61,7 @@ func (c *Container) getNetworkOptions(networkOpts map[string]types.PerNetworkOpt
 	return opts
 }
 
-// setUpNetwork will set up the the networks, on error it will also tear down the cni
+// setUpNetwork will set up the networks, on error it will also tear down the cni
 // networks. If rootless it will join/create the rootless network namespace.
 func (r *Runtime) setUpNetwork(ns string, opts types.NetworkOptions) (map[string]types.StatusBlock, error) {
 	rootlessNetNS, err := r.GetRootlessNetNs(true)
@@ -385,7 +385,7 @@ func (c *Container) NetworkDisconnect(nameOrID, netName string, force bool) erro
 		return err
 	}
 
-	// check if network exists and if the input is a ID we get the name
+	// check if network exists and if the input is an ID we get the name
 	// CNI and netavark and the libpod db only uses names so it is important that we only use the name
 	netName, err = c.runtime.normalizeNetworkName(netName)
 	if err != nil {
@@ -499,7 +499,7 @@ func (c *Container) NetworkConnect(nameOrID, netName string, netOpts types.PerNe
 		return err
 	}
 
-	// check if network exists and if the input is a ID we get the name
+	// check if network exists and if the input is an ID we get the name
 	// CNI and netavark and the libpod db only uses names so it is important that we only use the name
 	netName, err = c.runtime.normalizeNetworkName(netName)
 	if err != nil {

libpod/networking_linux.go

@@ -541,7 +541,7 @@ func (r *Runtime) GetRootlessNetNs(new bool) (*RootlessNetNS, error) {
 	// The CNI plugins and netavark need access to iptables in $PATH. As it turns out debian doesn't put
 	// /usr/sbin in $PATH for rootless users. This will break rootless networking completely.
 	// We might break existing users and we cannot expect everyone to change their $PATH so
-	// lets add /usr/sbin to $PATH ourselves.
+	// let's add /usr/sbin to $PATH ourselves.
 	path = os.Getenv("PATH")
 	if !strings.Contains(path, "/usr/sbin") {
 		path += ":/usr/sbin"

pkg/api/server/register_containers.go

@@ -749,7 +749,7 @@ func (s *APIServer) registerContainersHandlers(r *mux.Router) error {
 	//        - `health`=(`starting`, `healthy`, `unhealthy` or `none`)
 	//        - `id=<ID>` a container's ID
 	//        - `is-task`=(`true` or `false`)
-	//        - `label`=(`key` or `"key=value"`) of an container label
+	//        - `label`=(`key` or `"key=value"`) of a container label
 	//        - `name=<name>` a container's name
 	//        - `network`=(`<network id>` or `<network name>`)
 	//        - `pod`=(`<pod id>` or `<pod name>`)

pkg/api/server/register_images.go

@@ -1351,7 +1351,7 @@ func (s *APIServer) registerImagesHandlers(r *mux.Router) error {
 	//   - images
 	// summary: Report on changes to images's filesystem; adds, deletes or modifications.
 	// description: |
-	//   Returns which files in a images's filesystem have been added, deleted, or modified. The Kind of modification can be one of:
+	//   Returns which files in an image's filesystem have been added, deleted, or modified. The Kind of modification can be one of:
 	//
 	//   0: Modified
 	//   1: Added

pkg/bindings/test/pods_test.go

@@ -49,7 +49,7 @@ var _ = Describe("Podman pods", func() {
 		code, _ := bindings.CheckResponseCode(err)
 		Expect(code).To(BeNumerically("==", http.StatusNotFound))
 
-		// Inspect an valid pod name
+		// Inspect a valid pod name
 		response, err := pods.Inspect(bt.conn, newpod, nil)
 		Expect(err).ToNot(HaveOccurred())
 		Expect(response.Name).To(Equal(newpod))

pkg/domain/entities/images.go

@@ -179,7 +179,7 @@ type ImagePullReport struct {
 
 // ImagePushOptions are the arguments for pushing images.
 type ImagePushOptions struct {
-	// All indicates that all images referenced in an manifest list should be pushed
+	// All indicates that all images referenced in a manifest list should be pushed
 	All bool
 	// Authfile is the path to the authentication file. Ignored for remote
 	// calls.

pkg/domain/infra/abi/play.go

@@ -625,7 +625,7 @@ func (ic *ContainerEngine) playKubePod(ctx context.Context, podName string, podY
 		}
 	}
 
-	// Add the the original container names from the kube yaml as aliases for it. This will allow network to work with
+	// Add the original container names from the kube yaml as aliases for it. This will allow network to work with
 	// both just containerName as well as containerName-podName.
 	// In the future, we want to extend this to the CLI as well, where the name of the container created will not have
 	// the podName appended to it, but this is a breaking change and will be done in podman 5.0

pkg/lookup/lookup.go

@@ -22,7 +22,7 @@ type Overrides struct {
 }
 
 // GetUserGroupInfo takes string forms of the container's mount path and the container user and
-// returns a ExecUser with uid, gid, sgids, and home.  And override can be provided for defaults.
+// returns an ExecUser with uid, gid, sgids, and home.  And override can be provided for defaults.
 func GetUserGroupInfo(containerMount, containerUser string, override *Overrides) (*user.ExecUser, error) {
 	var (
 		passwdDest, groupDest string

pkg/machine/qemu/machine.go

@@ -133,7 +133,7 @@ func (p *Virtualization) NewMachine(opts machine.InitOptions) (machine.VM, error
 		"-device", "virtio-serial",
 		// qemu needs to establish the long name; other connections can use the symlink'd
 		// Note both id and chardev start with an extra "a" because qemu requires that it
-		// starts with an letter but users can also use numbers
+		// starts with a letter but users can also use numbers
 		"-chardev", "socket,path=" + vm.ReadySocket.Path + ",server=on,wait=off,id=a" + vm.Name + "_ready",
 		"-device", "virtserialport,chardev=a" + vm.Name + "_ready" + ",name=org.fedoraproject.port.0",
 		"-pidfile", vm.VMPidFilePath.GetPath()}...)
@@ -1047,7 +1047,7 @@ func (v *MachineVM) State(bypass bool) (machine.Status, error) {
 			logrus.Error(err)
 		}
 	}()
-	// If there is a monitor, lets see if we can query state
+	// If there is a monitor, let's see if we can query state
 	return v.checkStatus(monitor)
 }
 

pkg/namespaces/namespaces.go

@@ -122,7 +122,7 @@ func (n UsernsMode) IsDefaultValue() bool {
 	return n == "" || n == defaultType
 }
 
-// GetAutoOptions returns a AutoUserNsOptions with the settings to automatically set up
+// GetAutoOptions returns an AutoUserNsOptions with the settings to automatically set up
 // a user namespace.
 func (n UsernsMode) GetAutoOptions() (*types.AutoUserNsOptions, error) {
 	parts := strings.SplitN(string(n), ":", 2)

pkg/specgen/generate/container_create.go

@@ -181,7 +181,7 @@ func MakeContainer(ctx context.Context, rt *libpod.Runtime, s *specgen.SpecGener
 
 	_, err = rt.LookupPod(s.Hostname)
 	if len(s.Hostname) > 0 && !s.UtsNS.IsPrivate() && err == nil {
-		// ok, we are incorrectly setting the pod as the hostname, lets undo that before validation
+		// ok, we are incorrectly setting the pod as the hostname, let's undo that before validation
 		s.Hostname = ""
 	}
 	if err := s.Validate(); err != nil {

pkg/specgen/generate/security_linux.go

@@ -115,7 +115,7 @@ func securityConfigureGenerator(s *specgen.SpecGenerator, g *generate.Generator,
 
 		privCapsRequired := []string{}
 
-		// If the container image specifies an label with a
+		// If the container image specifies a label with a
 		// capabilities.ContainerImageLabel then split the comma separated list
 		// of capabilities and record them.  This list indicates the only
 		// capabilities, required to run the container.

pkg/util/utils.go

@@ -624,7 +624,7 @@ func SizeOfPath(path string) (uint64, error) {
 	return uint64(size), err
 }
 
-// EncryptConfig translates encryptionKeys into a EncriptionsConfig structure
+// EncryptConfig translates encryptionKeys into an EncriptionsConfig structure
 func EncryptConfig(encryptionKeys []string, encryptLayers []int) (*encconfig.EncryptConfig, *[]int, error) {
 	var encLayers *[]int
 	var encConfig *encconfig.EncryptConfig

test/e2e/pod_initcontainers_test.go

@@ -93,7 +93,7 @@ var _ = Describe("Podman init containers", func() {
 		// Container was rm'd
 		// Expect(check).Should(Exit(1))
 		Expect(check.ExitCode()).To(Equal(1), "I dont understand why the other way does not work")
-		// Lets double check with a stop and start
+		// Let's double check with a stop and start
 		stopPod := podmanTest.Podman([]string{"pod", "stop", "foobar"})
 		stopPod.WaitWithDefaultTimeout()
 		Expect(stopPod).Should(Exit(0))

test/e2e/ps_test.go

@@ -305,7 +305,7 @@ var _ = Describe("Podman ps", func() {
 		Expect(result).Should(Exit(0))
 		Expect(result.OutputToString()).To(Equal(cid))
 
-		// Query for an non-existing image using regex should not match anything
+		// Query for a non-existing image using regex should not match anything
 		result = podmanTest.Podman([]string{"ps", "-q", "--no-trunc", "-a", "--filter", "ancestor=^quai.io/libpod/alpi"})
 		result.WaitWithDefaultTimeout()
 		Expect(result).Should(Exit(0))

test/e2e/run_test.go

@@ -249,7 +249,7 @@ var _ = Describe("Podman run", func() {
 		Expect(esession).Should(Exit(0))
 		Expect(tarball).Should(BeARegularFile())
 
-		// N/B: This will loose any extended attributes like SELinux types
+		// N/B: This will lose any extended attributes like SELinux types
 		GinkgoWriter.Printf("Extracting container root tarball\n")
 		tarsession := SystemExec("tar", []string{"xf", tarball, "-C", rootfs})
 		Expect(tarsession).Should(Exit(0))

test/system/035-logs.bats

@@ -322,7 +322,7 @@ function _log_test_follow_since() {
         sh -c "sleep 1; while :; do echo $content && sleep 5; done"
 
     # sleep is required to make sure the podman event backend no longer sees the start event in the log
-    # This value must be greater or equal than the the value given in --since below
+    # This value must be greater or equal than the value given in --since below
     sleep 0.2
 
     # Make sure podman logs actually follows by giving a low timeout and check that the command times out

test/system/500-networking.bats

@@ -26,7 +26,7 @@ load helpers.network
     run_podman network create $net3
 
     run_podman network ls --quiet
-    # just check the the order of the created networks is correct
+    # just check that the order of the created networks is correct
     # we cannot do an exact match since developer and CI systems could contain more networks
     is "$output" ".*$net1.*$net2.*$net3.*podman.*" "networks sorted alphabetically"
 

test/system/700-play.bats

@@ -209,7 +209,7 @@ EOF
     # Stop the *main* container and make sure that
     #  1) The pod transitions to Exited
     #  2) The service container is stopped
-    #  #) The service container is marked as an service container
+    #  #) The service container is marked as a service container
     run_podman stop test_pod-test
     _ensure_pod_state test_pod Exited
     _ensure_container_running $service_container false

troubleshooting.md

@@ -458,7 +458,6 @@ the user session completed.
 Once the user logs out all the containers exit.
 
 #### Solution
-You'll need to either:
 
 ```console
 # loginctl enable-linger $UID