diff --git a/app.go b/app.go
index 5c616e6f51..a88dc49d31 100644
--- a/app.go
+++ b/app.go
@@ -305,6 +305,10 @@ func (a *App) RunContext(ctx context.Context, arguments []string) (err error) {
 		}
 	}
 
+	if err = runFlagActions(context, a.Flags); err != nil {
+		return err
+	}
+
 	args := context.Args()
 	if args.Present() {
 		name := args.First()
@@ -426,6 +430,10 @@ func (a *App) RunAsSubcommand(ctx *Context) (err error) {
 		}
 	}
 
+	if err = runFlagActions(context, a.Flags); err != nil {
+		return err
+	}
+
 	args := context.Args()
 	if args.Present() {
 		name := args.First()
@@ -506,6 +514,24 @@ func (a *App) handleExitCoder(context *Context, err error) {
 	}
 }
 
+func runFlagActions(c *Context, fs []Flag) error {
+	for _, f := range fs {
+		isSet := false
+		for _, name := range f.Names() {
+			if c.IsSet(name) {
+				isSet = true
+				break
+			}
+		}
+		if isSet {
+			if err := f.RunAction(c); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
 // Author represents someone who has contributed to a cli project.
 type Author struct {
 	Name  string // The Authors name
diff --git a/app_test.go b/app_test.go
index 76e211d681..0872db7d58 100644
--- a/app_test.go
+++ b/app_test.go
@@ -2034,6 +2034,10 @@ func (c *customBoolFlag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+func (c *customBoolFlag) RunAction(*Context) error {
+	return nil
+}
+
 func (c *customBoolFlag) IsSet() bool {
 	return false
 }
@@ -2253,3 +2257,66 @@ func TestSetupInitializesOnlyNilWriters(t *testing.T) {
 		t.Errorf("expected a.Writer to be os.Stdout")
 	}
 }
+
+func TestFlagAction(t *testing.T) {
+	r := []string{}
+	actionFunc := func(c *Context, s string) error {
+		r = append(r, s)
+		return nil
+	}
+
+	app := &App{
+		Name:   "command",
+		Writer: io.Discard,
+		Flags:  []Flag{&StringFlag{Name: "flag", Action: actionFunc}},
+		Commands: []*Command{
+			{
+				Name:  "command1",
+				Flags: []Flag{&StringFlag{Name: "flag1", Aliases: []string{"f1"}, Action: actionFunc}},
+				Subcommands: []*Command{
+					{
+						Name:  "command2",
+						Flags: []Flag{&StringFlag{Name: "flag2", Action: actionFunc}},
+					},
+				},
+			},
+		},
+	}
+
+	tests := []struct {
+		args []string
+		exp  []string
+	}{
+		{
+			args: []string{"command", "--flag=f"},
+			exp:  []string{"f"},
+		},
+		{
+			args: []string{"command", "command1", "-f1=f1", "command2"},
+			exp:  []string{"f1"},
+		},
+		{
+			args: []string{"command", "command1", "-f1=f1", "command2", "--flag2=f2"},
+			exp:  []string{"f1", "f2"},
+		},
+		{
+			args: []string{"command", "--flag=f", "command1", "-flag1=f1"},
+			exp:  []string{"f", "f1"},
+		},
+		{
+			args: []string{"command", "--flag=f", "command1", "-f1=f1"},
+			exp:  []string{"f", "f1"},
+		},
+		{
+			args: []string{"command", "--flag=f", "command1", "-f1=f1", "command2", "--flag2=f2"},
+			exp:  []string{"f", "f1", "f2"},
+		},
+	}
+
+	for _, test := range tests {
+		r = []string{}
+		err := app.Run(test.args)
+		expect(t, err, nil)
+		expect(t, r, test.exp)
+	}
+}
diff --git a/command.go b/command.go
index 3477686bb3..a5efbc749d 100644
--- a/command.go
+++ b/command.go
@@ -155,6 +155,10 @@ func (c *Command) Run(ctx *Context) (err error) {
 		}
 	}
 
+	if err = runFlagActions(context, c.Flags); err != nil {
+		return err
+	}
+
 	if c.Action == nil {
 		c.Action = helpSubcommand.Action
 	}
diff --git a/flag.go b/flag.go
index 49682f2994..a7ad939dc6 100644
--- a/flag.go
+++ b/flag.go
@@ -94,6 +94,7 @@ type Flag interface {
 	Apply(*flag.FlagSet) error
 	Names() []string
 	IsSet() bool
+	RunAction(*Context) error
 }
 
 // RequiredFlag is an interface that allows us to mark flags as required
diff --git a/flag_bool.go b/flag_bool.go
index 8bd582094f..17c69befec 100644
--- a/flag_bool.go
+++ b/flag_bool.go
@@ -19,6 +19,7 @@ type BoolFlag struct {
 	DefaultText string
 	Destination *bool
 	HasBeenSet  bool
+	Action      func(*Context, bool) error
 }
 
 // IsSet returns whether or not the flag has been set through env or file
@@ -63,6 +64,15 @@ func (f *BoolFlag) IsVisible() bool {
 	return !f.Hidden
 }
 
+// RunAction executes flag action if set
+func (f *BoolFlag) RunAction(c *Context) error {
+	if f.Action != nil {
+		return f.Action(c, c.Bool(f.Name))
+	}
+
+	return nil
+}
+
 // Apply populates the flag given the flag set and environment
 func (f *BoolFlag) Apply(set *flag.FlagSet) error {
 	if val, ok := flagFromEnvOrFile(f.EnvVars, f.FilePath); ok {
diff --git a/flag_duration.go b/flag_duration.go
index 28f3978051..addcd23e14 100644
--- a/flag_duration.go
+++ b/flag_duration.go
@@ -19,6 +19,7 @@ type DurationFlag struct {
 	DefaultText string
 	Destination *time.Duration
 	HasBeenSet  bool
+	Action      func(*Context, time.Duration) error
 }
 
 // IsSet returns whether or not the flag has been set through env or file
@@ -88,6 +89,15 @@ func (f *DurationFlag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+// RunAction executes flag action if set
+func (f *DurationFlag) RunAction(c *Context) error {
+	if f.Action != nil {
+		return f.Action(c, c.Duration(f.Name))
+	}
+
+	return nil
+}
+
 // Duration looks up the value of a local DurationFlag, returns
 // 0 if not found
 func (c *Context) Duration(name string) time.Duration {
diff --git a/flag_float64.go b/flag_float64.go
index 10fb8dfc1c..4398dd2ab2 100644
--- a/flag_float64.go
+++ b/flag_float64.go
@@ -19,6 +19,7 @@ type Float64Flag struct {
 	DefaultText string
 	Destination *float64
 	HasBeenSet  bool
+	Action      func(*Context, float64) error
 }
 
 // IsSet returns whether or not the flag has been set through env or file
@@ -89,6 +90,15 @@ func (f *Float64Flag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+// RunAction executes flag action if set
+func (f *Float64Flag) RunAction(c *Context) error {
+	if f.Action != nil {
+		return f.Action(c, c.Float64(f.Name))
+	}
+
+	return nil
+}
+
 // Float64 looks up the value of a local Float64Flag, returns
 // 0 if not found
 func (c *Context) Float64(name string) float64 {
diff --git a/flag_float64_slice.go b/flag_float64_slice.go
index 385732e17c..593f7f6ca5 100644
--- a/flag_float64_slice.go
+++ b/flag_float64_slice.go
@@ -85,6 +85,7 @@ type Float64SliceFlag struct {
 	Value       *Float64Slice
 	DefaultText string
 	HasBeenSet  bool
+	Action      func(*Context, []float64) error
 }
 
 // IsSet returns whether or not the flag has been set through env or file
@@ -162,6 +163,15 @@ func (f *Float64SliceFlag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+// RunAction executes flag action if set
+func (f *Float64SliceFlag) RunAction(c *Context) error {
+	if f.Action != nil {
+		return f.Action(c, c.Float64Slice(f.Name))
+	}
+
+	return nil
+}
+
 // Float64Slice looks up the value of a local Float64SliceFlag, returns
 // nil if not found
 func (c *Context) Float64Slice(name string) []float64 {
diff --git a/flag_generic.go b/flag_generic.go
index fdf586d127..a1040f3efe 100644
--- a/flag_generic.go
+++ b/flag_generic.go
@@ -24,6 +24,7 @@ type GenericFlag struct {
 	Value       Generic
 	DefaultText string
 	HasBeenSet  bool
+	Action      func(*Context, interface{}) error
 }
 
 // IsSet returns whether or not the flag has been set through env or file
@@ -91,6 +92,15 @@ func (f GenericFlag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+// RunAction executes flag action if set
+func (f *GenericFlag) RunAction(c *Context) error {
+	if f.Action != nil {
+		return f.Action(c, c.Generic(f.Name))
+	}
+
+	return nil
+}
+
 // Generic looks up the value of a local GenericFlag, returns
 // nil if not found
 func (c *Context) Generic(name string) interface{} {
diff --git a/flag_int.go b/flag_int.go
index 1ebe3569c1..8d963cc2bb 100644
--- a/flag_int.go
+++ b/flag_int.go
@@ -19,6 +19,7 @@ type IntFlag struct {
 	DefaultText string
 	Destination *int
 	HasBeenSet  bool
+	Action      func(*Context, int) error
 }
 
 // IsSet returns whether or not the flag has been set through env or file
@@ -89,6 +90,15 @@ func (f *IntFlag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+// RunAction executes flag action if set
+func (f *IntFlag) RunAction(c *Context) error {
+	if f.Action != nil {
+		return f.Action(c, c.Int(f.Name))
+	}
+
+	return nil
+}
+
 // Int looks up the value of a local IntFlag, returns
 // 0 if not found
 func (c *Context) Int(name string) int {
diff --git a/flag_int64.go b/flag_int64.go
index ecf0e9ef6f..044e511547 100644
--- a/flag_int64.go
+++ b/flag_int64.go
@@ -19,6 +19,7 @@ type Int64Flag struct {
 	DefaultText string
 	Destination *int64
 	HasBeenSet  bool
+	Action      func(*Context, int64) error
 }
 
 // IsSet returns whether or not the flag has been set through env or file
@@ -88,6 +89,15 @@ func (f *Int64Flag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+// RunAction executes flag action if set
+func (f *Int64Flag) RunAction(c *Context) error {
+	if f.Action != nil {
+		return f.Action(c, c.Int64(f.Name))
+	}
+
+	return nil
+}
+
 // Int64 looks up the value of a local Int64Flag, returns
 // 0 if not found
 func (c *Context) Int64(name string) int64 {
diff --git a/flag_int64_slice.go b/flag_int64_slice.go
index f5c6939639..2338dff188 100644
--- a/flag_int64_slice.go
+++ b/flag_int64_slice.go
@@ -86,6 +86,7 @@ type Int64SliceFlag struct {
 	Value       *Int64Slice
 	DefaultText string
 	HasBeenSet  bool
+	Action      func(*Context, []int64) error
 }
 
 // IsSet returns whether or not the flag has been set through env or file
@@ -161,6 +162,15 @@ func (f *Int64SliceFlag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+// RunAction executes flag action if set
+func (f *Int64SliceFlag) RunAction(c *Context) error {
+	if f.Action != nil {
+		return f.Action(c, c.Int64Slice(f.Name))
+	}
+
+	return nil
+}
+
 // Int64Slice looks up the value of a local Int64SliceFlag, returns
 // nil if not found
 func (c *Context) Int64Slice(name string) []int64 {
diff --git a/flag_int_slice.go b/flag_int_slice.go
index 94c668e9f1..6c427c1d6f 100644
--- a/flag_int_slice.go
+++ b/flag_int_slice.go
@@ -97,6 +97,7 @@ type IntSliceFlag struct {
 	Value       *IntSlice
 	DefaultText string
 	HasBeenSet  bool
+	Action      func(*Context, []int) error
 }
 
 // IsSet returns whether or not the flag has been set through env or file
@@ -172,6 +173,15 @@ func (f *IntSliceFlag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+// RunAction executes flag action if set
+func (f *IntSliceFlag) RunAction(c *Context) error {
+	if f.Action != nil {
+		return f.Action(c, c.IntSlice(f.Name))
+	}
+
+	return nil
+}
+
 // IntSlice looks up the value of a local IntSliceFlag, returns
 // nil if not found
 func (c *Context) IntSlice(name string) []int {
diff --git a/flag_path.go b/flag_path.go
index b3aa9191d3..6bd08af82a 100644
--- a/flag_path.go
+++ b/flag_path.go
@@ -15,6 +15,7 @@ type PathFlag struct {
 	DefaultText string
 	Destination *string
 	HasBeenSet  bool
+	Action      func(*Context, string) error
 }
 
 // IsSet returns whether or not the flag has been set through env or file
@@ -77,6 +78,15 @@ func (f *PathFlag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+// RunAction executes flag action if set
+func (f *PathFlag) RunAction(c *Context) error {
+	if f.Action != nil {
+		return f.Action(c, c.Path(f.Name))
+	}
+
+	return nil
+}
+
 // Path looks up the value of a local PathFlag, returns
 // "" if not found
 func (c *Context) Path(name string) string {
diff --git a/flag_string.go b/flag_string.go
index aad4c43a9c..0073ebc4e3 100644
--- a/flag_string.go
+++ b/flag_string.go
@@ -16,6 +16,7 @@ type StringFlag struct {
 	DefaultText string
 	Destination *string
 	HasBeenSet  bool
+	Action      func(*Context, string) error
 }
 
 // IsSet returns whether or not the flag has been set through env or file
@@ -78,6 +79,15 @@ func (f *StringFlag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+// RunAction executes flag action if set
+func (f *StringFlag) RunAction(c *Context) error {
+	if f.Action != nil {
+		return f.Action(c, c.String(f.Name))
+	}
+
+	return nil
+}
+
 // String looks up the value of a local StringFlag, returns
 // "" if not found
 func (c *Context) String(name string) string {
diff --git a/flag_string_slice.go b/flag_string_slice.go
index 5269643105..e216f337e0 100644
--- a/flag_string_slice.go
+++ b/flag_string_slice.go
@@ -82,6 +82,7 @@ type StringSliceFlag struct {
 	DefaultText string
 	HasBeenSet  bool
 	Destination *StringSlice
+	Action      func(*Context, []string) error
 }
 
 // IsSet returns whether or not the flag has been set through env or file
@@ -173,6 +174,15 @@ func (f *StringSliceFlag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+// RunAction executes flag action if set
+func (f *StringSliceFlag) RunAction(c *Context) error {
+	if f.Action != nil {
+		return f.Action(c, c.StringSlice(f.Name))
+	}
+
+	return nil
+}
+
 // StringSlice looks up the value of a local StringSliceFlag, returns
 // nil if not found
 func (c *Context) StringSlice(name string) []string {
diff --git a/flag_timestamp.go b/flag_timestamp.go
index 7458a79b6a..09c77edbc2 100644
--- a/flag_timestamp.go
+++ b/flag_timestamp.go
@@ -72,6 +72,7 @@ type TimestampFlag struct {
 	DefaultText string
 	HasBeenSet  bool
 	Destination *Timestamp
+	Action      func(*Context, *time.Time) error
 }
 
 // IsSet returns whether or not the flag has been set through env or file
@@ -151,6 +152,15 @@ func (f *TimestampFlag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+// RunAction executes flag action if set
+func (f *TimestampFlag) RunAction(c *Context) error {
+	if f.Action != nil {
+		return f.Action(c, c.Timestamp(f.Name))
+	}
+
+	return nil
+}
+
 // Timestamp gets the timestamp from a flag name
 func (c *Context) Timestamp(name string) *time.Time {
 	if fs := c.lookupFlagSet(name); fs != nil {
diff --git a/flag_uint.go b/flag_uint.go
index 23a70a7f90..1b8dd57863 100644
--- a/flag_uint.go
+++ b/flag_uint.go
@@ -19,6 +19,7 @@ type UintFlag struct {
 	DefaultText string
 	Destination *uint
 	HasBeenSet  bool
+	Action      func(*Context, uint) error
 }
 
 // IsSet returns whether or not the flag has been set through env or file
@@ -82,6 +83,15 @@ func (f *UintFlag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+// RunAction executes flag action if set
+func (f *UintFlag) RunAction(c *Context) error {
+	if f.Action != nil {
+		return f.Action(c, c.Uint(f.Name))
+	}
+
+	return nil
+}
+
 // GetValue returns the flags value as string representation and an empty
 // string if the flag takes no value at all.
 func (f *UintFlag) GetValue() string {
diff --git a/flag_uint64.go b/flag_uint64.go
index a2df024e18..49d1653a12 100644
--- a/flag_uint64.go
+++ b/flag_uint64.go
@@ -19,6 +19,7 @@ type Uint64Flag struct {
 	DefaultText string
 	Destination *uint64
 	HasBeenSet  bool
+	Action      func(*Context, uint64) error
 }
 
 // IsSet returns whether or not the flag has been set through env or file
@@ -82,6 +83,15 @@ func (f *Uint64Flag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+// RunAction executes flag action if set
+func (f *Uint64Flag) RunAction(c *Context) error {
+	if f.Action != nil {
+		return f.Action(c, c.Uint64(f.Name))
+	}
+
+	return nil
+}
+
 // GetValue returns the flags value as string representation and an empty
 // string if the flag takes no value at all.
 func (f *Uint64Flag) GetValue() string {