Version Flag
The default version flag (-v/--version) is defined as cli.VersionFlag, which
is checked by the cli internals in order to print the App.Version via
cli.VersionPrinter and break execution.
Customization¶
The default flag may be customized to something other than -v/--version by
setting cli.VersionFlag, e.g.:
package main
import (
"log"
"os"
"github.com/urfave/cli"
)
func main() {
cli.VersionFlag = cli.BoolFlag{
Name: "print-version, V",
Usage: "print only the version",
}
app := cli.NewApp()
app.Name = "partay"
app.Version = "19.99.0"
err := app.Run(os.Args)
if err != nil {
log.Fatal(err)
}
}
Alternatively, the version printer at cli.VersionPrinter may be overridden, e.g.:
package main
import (
"fmt"
"log"
"os"
"github.com/urfave/cli"
)
var (
Revision = "fafafaf"
)
func main() {
cli.VersionPrinter = func(c *cli.Context) {
fmt.Printf("version=%s revision=%s\n", c.App.Version, Revision)
}
app := cli.NewApp()
app.Name = "partay"
app.Version = "19.99.0"
err := app.Run(os.Args)
if err != nil {
log.Fatal(err)
}
}
Full API Example¶
Notice: This is a contrived (functioning) example meant strictly for API demonstration purposes. Use of one's imagination is encouraged.
package main
import (
"errors"
"flag"
"fmt"
"io"
"os"
"time"
"github.com/urfave/cli"
)
func init() {
cli.AppHelpTemplate += "\nCUSTOMIZED: you bet ur muffins\n"
cli.CommandHelpTemplate += "\nYMMV\n"
cli.SubcommandHelpTemplate += "\nor something\n"
cli.HelpFlag = cli.BoolFlag{Name: "halp"}
cli.BashCompletionFlag = cli.BoolFlag{Name: "compgen", Hidden: true}
cli.VersionFlag = cli.BoolFlag{Name: "print-version, V"}
cli.HelpPrinter = func(w io.Writer, templ string, data interface{}) {
fmt.Fprintf(w, "best of luck to you\n")
}
cli.VersionPrinter = func(c *cli.Context) {
fmt.Fprintf(c.App.Writer, "version=%s\n", c.App.Version)
}
cli.OsExiter = func(c int) {
fmt.Fprintf(cli.ErrWriter, "refusing to exit %d\n", c)
}
cli.ErrWriter = io.Discard
cli.FlagStringer = func(fl cli.Flag) string {
return fmt.Sprintf("\t\t%s", fl.GetName())
}
}
type hexWriter struct{}
func (w *hexWriter) Write(p []byte) (int, error) {
for _, b := range p {
fmt.Printf("%x", b)
}
fmt.Printf("\n")
return len(p), nil
}
type genericType struct{
s string
}
func (g *genericType) Set(value string) error {
g.s = value
return nil
}
func (g *genericType) String() string {
return g.s
}
func main() {
app := cli.NewApp()
app.Name = "kənˈtrīv"
app.Version = "19.99.0"
app.Compiled = time.Now()
app.Authors = []cli.Author{
cli.Author{
Name: "Example Human",
Email: "human@example.com",
},
}
app.Copyright = "(c) 1999 Serious Enterprise"
app.HelpName = "contrive"
app.Usage = "demonstrate available API"
app.UsageText = "contrive - demonstrating the available API"
app.ArgsUsage = "[args and such]"
app.Commands = []cli.Command{
cli.Command{
Name: "doo",
Aliases: []string{"do"},
Category: "motion",
Usage: "do the doo",
UsageText: "doo - does the dooing",
Description: "no really, there is a lot of dooing to be done",
ArgsUsage: "[arrgh]",
Flags: []cli.Flag{
cli.BoolFlag{Name: "forever, forevvarr"},
},
Subcommands: cli.Commands{
cli.Command{
Name: "wop",
Action: wopAction,
},
},
SkipFlagParsing: false,
HideHelp: false,
Hidden: false,
HelpName: "doo!",
BashComplete: func(c *cli.Context) {
fmt.Fprintf(c.App.Writer, "--better\n")
},
Before: func(c *cli.Context) error {
fmt.Fprintf(c.App.Writer, "brace for impact\n")
return nil
},
After: func(c *cli.Context) error {
fmt.Fprintf(c.App.Writer, "did we lose anyone?\n")
return nil
},
Action: func(c *cli.Context) error {
c.Command.FullName()
c.Command.HasName("wop")
c.Command.Names()
c.Command.VisibleFlags()
fmt.Fprintf(c.App.Writer, "dodododododoodododddooooododododooo\n")
if c.Bool("forever") {
c.Command.Run(c)
}
return nil
},
OnUsageError: func(c *cli.Context, err error, isSubcommand bool) error {
fmt.Fprintf(c.App.Writer, "for shame\n")
return err
},
},
}
app.Flags = []cli.Flag{
cli.BoolFlag{Name: "fancy"},
cli.BoolTFlag{Name: "fancier"},
cli.DurationFlag{Name: "howlong, H", Value: time.Second * 3},
cli.Float64Flag{Name: "howmuch"},
cli.GenericFlag{Name: "wat", Value: &genericType{}},
cli.Int64Flag{Name: "longdistance"},
cli.Int64SliceFlag{Name: "intervals"},
cli.IntFlag{Name: "distance"},
cli.IntSliceFlag{Name: "times"},
cli.StringFlag{Name: "dance-move, d"},
cli.StringSliceFlag{Name: "names, N"},
cli.UintFlag{Name: "age"},
cli.Uint64Flag{Name: "bigage"},
}
app.EnableBashCompletion = true
app.UseShortOptionHandling = true
app.HideHelp = false
app.HideVersion = false
app.BashComplete = func(c *cli.Context) {
fmt.Fprintf(c.App.Writer, "lipstick\nkiss\nme\nlipstick\nringo\n")
}
app.Before = func(c *cli.Context) error {
fmt.Fprintf(c.App.Writer, "HEEEERE GOES\n")
return nil
}
app.After = func(c *cli.Context) error {
fmt.Fprintf(c.App.Writer, "Phew!\n")
return nil
}
app.CommandNotFound = func(c *cli.Context, command string) {
fmt.Fprintf(c.App.Writer, "Thar be no %q here.\n", command)
}
app.OnUsageError = func(c *cli.Context, err error, isSubcommand bool) error {
if isSubcommand {
return err
}
fmt.Fprintf(c.App.Writer, "WRONG: %#v\n", err)
return nil
}
app.Action = func(c *cli.Context) error {
cli.DefaultAppComplete(c)
cli.HandleExitCoder(errors.New("not an exit coder, though"))
cli.ShowAppHelp(c)
cli.ShowCommandCompletions(c, "nope")
cli.ShowCommandHelp(c, "also-nope")
cli.ShowCompletions(c)
cli.ShowSubcommandHelp(c)
cli.ShowVersion(c)
categories := c.App.Categories()
categories.AddCommand("sounds", cli.Command{
Name: "bloop",
})
for _, category := range c.App.Categories() {
fmt.Fprintf(c.App.Writer, "%s\n", category.Name)
fmt.Fprintf(c.App.Writer, "%#v\n", category.Commands)
fmt.Fprintf(c.App.Writer, "%#v\n", category.VisibleCommands())
}
fmt.Printf("%#v\n", c.App.Command("doo"))
if c.Bool("infinite") {
c.App.Run([]string{"app", "doo", "wop"})
}
if c.Bool("forevar") {
c.App.RunAsSubcommand(c)
}
c.App.Setup()
fmt.Printf("%#v\n", c.App.VisibleCategories())
fmt.Printf("%#v\n", c.App.VisibleCommands())
fmt.Printf("%#v\n", c.App.VisibleFlags())
fmt.Printf("%#v\n", c.Args().First())
if len(c.Args()) > 0 {
fmt.Printf("%#v\n", c.Args()[1])
}
fmt.Printf("%#v\n", c.Args().Present())
fmt.Printf("%#v\n", c.Args().Tail())
set := flag.NewFlagSet("contrive", 0)
nc := cli.NewContext(c.App, set, c)
fmt.Printf("%#v\n", nc.Args())
fmt.Printf("%#v\n", nc.Bool("nope"))
fmt.Printf("%#v\n", nc.BoolT("nerp"))
fmt.Printf("%#v\n", nc.Duration("howlong"))
fmt.Printf("%#v\n", nc.Float64("hay"))
fmt.Printf("%#v\n", nc.Generic("bloop"))
fmt.Printf("%#v\n", nc.Int64("bonk"))
fmt.Printf("%#v\n", nc.Int64Slice("burnks"))
fmt.Printf("%#v\n", nc.Int("bips"))
fmt.Printf("%#v\n", nc.IntSlice("blups"))
fmt.Printf("%#v\n", nc.String("snurt"))
fmt.Printf("%#v\n", nc.StringSlice("snurkles"))
fmt.Printf("%#v\n", nc.Uint("flub"))
fmt.Printf("%#v\n", nc.Uint64("florb"))
fmt.Printf("%#v\n", nc.GlobalBool("global-nope"))
fmt.Printf("%#v\n", nc.GlobalBoolT("global-nerp"))
fmt.Printf("%#v\n", nc.GlobalDuration("global-howlong"))
fmt.Printf("%#v\n", nc.GlobalFloat64("global-hay"))
fmt.Printf("%#v\n", nc.GlobalGeneric("global-bloop"))
fmt.Printf("%#v\n", nc.GlobalInt("global-bips"))
fmt.Printf("%#v\n", nc.GlobalIntSlice("global-blups"))
fmt.Printf("%#v\n", nc.GlobalString("global-snurt"))
fmt.Printf("%#v\n", nc.GlobalStringSlice("global-snurkles"))
fmt.Printf("%#v\n", nc.FlagNames())
fmt.Printf("%#v\n", nc.GlobalFlagNames())
fmt.Printf("%#v\n", nc.GlobalIsSet("wat"))
fmt.Printf("%#v\n", nc.GlobalSet("wat", "nope"))
fmt.Printf("%#v\n", nc.NArg())
fmt.Printf("%#v\n", nc.NumFlags())
fmt.Printf("%#v\n", nc.Parent())
nc.Set("wat", "also-nope")
ec := cli.NewExitError("ohwell", 86)
fmt.Fprintf(c.App.Writer, "%d", ec.ExitCode())
fmt.Printf("made it!\n")
return nil
}
if os.Getenv("HEXY") != "" {
app.Writer = &hexWriter{}
app.ErrWriter = &hexWriter{}
}
app.Metadata = map[string]interface{}{
"layers": "many",
"explicable": false,
"whatever-values": 19.99,
}
// ignore error so we don't exit non-zero and break gfmrun README example tests
_ = app.Run(os.Args)
}
func wopAction(c *cli.Context) error {
fmt.Fprintf(c.App.Writer, ":wave: over here, eh\n")
return nil
}
Last update:
February 1, 2023