cli: automatically expand exec -it to -i -t

.changelog/27906.txt

@@ -0,0 +1,3 @@
+```release-note:improvement
+cli: Automatically expand `nomad exec -it` to `-i -t`
+```

command/alloc_exec.go

@@ -118,6 +118,7 @@ func (l *AllocExecCommand) Run(args []string) int {
 	flags.StringVar(&task, "task", "", "")
 	flags.StringVar(&group, "group", "", "")
 
+	args = expandITFlags(args)
 	if err := flags.Parse(args); err != nil {
 		return 1
 	}
@@ -340,6 +341,22 @@ func setRawTerminalOutput(stream interface{}) (cleanup func(), err error) {
 	return func() { term.RestoreTerminal(fd, state) }, nil
 }
 
+// expandITFlags preprocesses args to expand the combined short boolean flags
+// -it and -ti into their individual forms -i -t, mirroring the convention
+// established by tools like docker and ssh.
+func expandITFlags(args []string) []string {
+	expanded := make([]string, 0, len(args))
+	for _, arg := range args {
+		switch arg {
+		case "-it", "-ti":
+			expanded = append(expanded, "-i", "-t")
+		default:
+			expanded = append(expanded, arg)
+		}
+	}
+	return expanded
+}
+
 // watchTerminalSize watches terminal size changes to propagate to remote tty.
 func watchTerminalSize(out io.Writer, resize chan<- api.TerminalSize) (func(), error) {
 	fd, isTerminal := term.GetFdInfo(out)

command/alloc_exec_test.go

@@ -77,6 +77,11 @@ func TestAllocExecCommand_Fails(t *testing.T) {
 			[]string{"-address=" + url, "-e", "es", "26470238-5CF2-438F-8772-DC67CFB0705C", "/bin/bash"},
 			`-e requires 'none' or a single character`,
 		},
+		{
+			"-it with stdin disabled is rejected",
+			[]string{"-it", "-i=false", "26470238-5CF2-438F-8772-DC67CFB0705C", "/bin/bash"},
+			`-i must be enabled if running with tty`,
+		},
 	}
 
 	for _, c := range cases {
@@ -165,6 +170,49 @@ func TestAllocExecCommand_AutocompleteArgs(t *testing.T) {
 	must.Eq(t, a.ID, res[0])
 }
 
+func TestExpandITFlags(t *testing.T) {
+	ci.Parallel(t)
+
+	cases := []struct {
+		name     string
+		input    []string
+		expected []string
+	}{
+		{
+			name:     "no combined flags",
+			input:    []string{"-i", "-t", "alloc", "/bin/sh"},
+			expected: []string{"-i", "-t", "alloc", "/bin/sh"},
+		},
+		{
+			name:     "-it expanded",
+			input:    []string{"-it", "alloc", "/bin/sh"},
+			expected: []string{"-i", "-t", "alloc", "/bin/sh"},
+		},
+		{
+			name:     "-ti expanded",
+			input:    []string{"-ti", "alloc", "/bin/sh"},
+			expected: []string{"-i", "-t", "alloc", "/bin/sh"},
+		},
+		{
+			name:     "-it with other flags",
+			input:    []string{"-address=http://localhost", "-it", "alloc", "/bin/sh"},
+			expected: []string{"-address=http://localhost", "-i", "-t", "alloc", "/bin/sh"},
+		},
+		{
+			name:     "empty args",
+			input:    []string{},
+			expected: []string{},
+		},
+	}
+
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			result := expandITFlags(c.input)
+			must.Eq(t, c.expected, result)
+		})
+	}
+}
+
 func TestAllocExecCommand_Run(t *testing.T) {
 	ci.Parallel(t)
 	srv, client, url := testServer(t, true, nil)