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|
---
tags:
- v2
search:
boost: 2
---
The default help flag (`-h/--help`) is defined as `cli.HelpFlag` and is checked
by the cli internals in order to print generated help text for the app, command,
or subcommand, and break execution.
#### Customization
All of the help text generation may be customized, and at multiple levels. The
templates are exposed as variables `AppHelpTemplate`, `CommandHelpTemplate`, and
`SubcommandHelpTemplate` which may be reassigned or augmented, and full override
is possible by assigning a compatible func to the `cli.HelpPrinter` variable,
e.g.:
<!-- {
"output": "Ha HA. I pwnd the help!!1"
} -->
```go
package main
import (
"fmt"
"io"
"os"
"github.com/urfave/cli/v2"
)
func main() {
// EXAMPLE: Append to an existing template
cli.AppHelpTemplate = fmt.Sprintf(`%s
WEBSITE: http://awesometown.example.com
SUPPORT: support@awesometown.example.com
`, cli.AppHelpTemplate)
// EXAMPLE: Override a template
cli.AppHelpTemplate = `NAME:
{{.Name}} - {{.Usage}}
USAGE:
{{.HelpName}} {{if .VisibleFlags}}[global options]{{end}}{{if .Commands}} command [command options]{{end}} {{if .ArgsUsage}}{{.ArgsUsage}}{{else}}[arguments...]{{end}}
{{if len .Authors}}
AUTHOR:
{{range .Authors}}{{ . }}{{end}}
{{end}}{{if .Commands}}
COMMANDS:
{{range .Commands}}{{if not .HideHelp}} {{join .Names ", "}}{{ "\t"}}{{.Usage}}{{ "\n" }}{{end}}{{end}}{{end}}{{if .VisibleFlags}}
GLOBAL OPTIONS:
{{range .VisibleFlags}}{{.}}
{{end}}{{end}}{{if .Copyright }}
COPYRIGHT:
{{.Copyright}}
{{end}}{{if .Version}}
VERSION:
{{.Version}}
{{end}}
`
// EXAMPLE: Replace the `HelpPrinter` func
cli.HelpPrinter = func(w io.Writer, templ string, data interface{}) {
fmt.Println("Ha HA. I pwnd the help!!1")
}
(&cli.App{}).Run(os.Args)
}
```
The default flag may be customized to something other than `-h/--help` by
setting `cli.HelpFlag`, e.g.:
<!-- {
"args": ["--halp"],
"output": "haaaaalp.*HALP"
} -->
```go
package main
import (
"os"
"github.com/urfave/cli/v2"
)
func main() {
cli.HelpFlag = &cli.BoolFlag{
Name: "haaaaalp",
Aliases: []string{"halp"},
Usage: "HALP",
EnvVars: []string{"SHOW_HALP", "HALPPLZ"},
}
(&cli.App{}).Run(os.Args)
}
```
|
