cobra/bash_completions.go
2023-03-05 21:28:31 -05:00

713 lines
22 KiB
Go

// Copyright 2013-2023 The Cobra Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package cobra
import (
"bytes"
"fmt"
"io"
"os"
"sort"
"strings"
"github.com/spf13/pflag"
)
// Annotations for Bash completion.
const (
BashCompFilenameExt = "cobra_annotation_bash_completion_filename_extensions"
BashCompCustom = "cobra_annotation_bash_completion_custom"
BashCompOneRequiredFlag = "cobra_annotation_bash_completion_one_required_flag"
BashCompSubdirsInDir = "cobra_annotation_bash_completion_subdirs_in_dir"
)
func writePreamble(buf io.StringWriter, name string) {
WriteStringAndCheck(buf, fmt.Sprintf("# bash completion for %-36s -*- shell-script -*-\n", name))
WriteStringAndCheck(buf, fmt.Sprintf(`
__%[1]s_debug()
{
if [[ -n ${BASH_COMP_DEBUG_FILE:-} ]]; then
echo "$*" >> "${BASH_COMP_DEBUG_FILE}"
fi
}
# Homebrew on Macs have version 1.3 of bash-completion which doesn't include
# _init_completion. This is a very minimal version of that function.
__%[1]s_init_completion()
{
COMPREPLY=()
_get_comp_words_by_ref "$@" cur prev words cword
}
__%[1]s_index_of_word()
{
local w word=$1
shift
index=0
for w in "$@"; do
[[ $w = "$word" ]] && return
index=$((index+1))
done
index=-1
}
__%[1]s_contains_word()
{
local w word=$1; shift
for w in "$@"; do
[[ $w = "$word" ]] && return
done
return 1
}
__%[1]s_handle_go_custom_completion()
{
__%[1]s_debug "${FUNCNAME[0]}: cur is ${cur}, words[*] is ${words[*]}, #words[@] is ${#words[@]}"
local shellCompDirectiveError=%[3]d
local shellCompDirectiveNoSpace=%[4]d
local shellCompDirectiveNoFileComp=%[5]d
local shellCompDirectiveFilterFileExt=%[6]d
local shellCompDirectiveFilterDirs=%[7]d
local out requestComp lastParam lastChar comp directive args
# Prepare the command to request completions for the program.
# Calling ${words[0]} instead of directly %[1]s allows to handle aliases
args=("${words[@]:1}")
# Disable ActiveHelp which is not supported for bash completion v1
requestComp="%[8]s=0 ${words[0]} %[2]s ${args[*]}"
lastParam=${words[$((${#words[@]}-1))]}
lastChar=${lastParam:$((${#lastParam}-1)):1}
__%[1]s_debug "${FUNCNAME[0]}: lastParam ${lastParam}, lastChar ${lastChar}"
if [ -z "${cur}" ] && [ "${lastChar}" != "=" ]; then
# If the last parameter is complete (there is a space following it)
# We add an extra empty parameter so we can indicate this to the go method.
__%[1]s_debug "${FUNCNAME[0]}: Adding extra empty parameter"
requestComp="${requestComp} \"\""
fi
__%[1]s_debug "${FUNCNAME[0]}: calling ${requestComp}"
# Use eval to handle any environment variables and such
out=$(eval "${requestComp}" 2>/dev/null)
# Extract the directive integer at the very end of the output following a colon (:)
directive=${out##*:}
# Remove the directive
out=${out%%:*}
if [ "${directive}" = "${out}" ]; then
# There is not directive specified
directive=0
fi
__%[1]s_debug "${FUNCNAME[0]}: the completion directive is: ${directive}"
__%[1]s_debug "${FUNCNAME[0]}: the completions are: ${out}"
if [ $((directive & shellCompDirectiveError)) -ne 0 ]; then
# Error code. No completion.
__%[1]s_debug "${FUNCNAME[0]}: received error from custom completion go code"
return
else
if [ $((directive & shellCompDirectiveNoSpace)) -ne 0 ]; then
if [[ $(type -t compopt) = "builtin" ]]; then
__%[1]s_debug "${FUNCNAME[0]}: activating no space"
compopt -o nospace
fi
fi
if [ $((directive & shellCompDirectiveNoFileComp)) -ne 0 ]; then
if [[ $(type -t compopt) = "builtin" ]]; then
__%[1]s_debug "${FUNCNAME[0]}: activating no file completion"
compopt +o default
fi
fi
fi
if [ $((directive & shellCompDirectiveFilterFileExt)) -ne 0 ]; then
# File extension filtering
local fullFilter filter filteringCmd
# Do not use quotes around the $out variable or else newline
# characters will be kept.
for filter in ${out}; do
fullFilter+="$filter|"
done
filteringCmd="_filedir $fullFilter"
__%[1]s_debug "File filtering command: $filteringCmd"
$filteringCmd
elif [ $((directive & shellCompDirectiveFilterDirs)) -ne 0 ]; then
# File completion for directories only
local subdir
# Use printf to strip any trailing newline
subdir=$(printf "%%s" "${out}")
if [ -n "$subdir" ]; then
__%[1]s_debug "Listing directories in $subdir"
__%[1]s_handle_subdirs_in_dir_flag "$subdir"
else
__%[1]s_debug "Listing directories in ."
_filedir -d
fi
else
while IFS='' read -r comp; do
COMPREPLY+=("$comp")
done < <(compgen -W "${out}" -- "$cur")
fi
}
__%[1]s_handle_reply()
{
__%[1]s_debug "${FUNCNAME[0]}"
local comp
case $cur in
-*)
if [[ $(type -t compopt) = "builtin" ]]; then
compopt -o nospace
fi
local allflags
if [ ${#must_have_one_flag[@]} -ne 0 ]; then
allflags=("${must_have_one_flag[@]}")
else
allflags=("${flags[*]} ${two_word_flags[*]}")
fi
while IFS='' read -r comp; do
COMPREPLY+=("$comp")
done < <(compgen -W "${allflags[*]}" -- "$cur")
if [[ $(type -t compopt) = "builtin" ]]; then
[[ "${COMPREPLY[0]}" == *= ]] || compopt +o nospace
fi
# complete after --flag=abc
if [[ $cur == *=* ]]; then
if [[ $(type -t compopt) = "builtin" ]]; then
compopt +o nospace
fi
local index flag
flag="${cur%%=*}"
__%[1]s_index_of_word "${flag}" "${flags_with_completion[@]}"
COMPREPLY=()
if [[ ${index} -ge 0 ]]; then
PREFIX=""
cur="${cur#*=}"
${flags_completion[${index}]}
if [ -n "${ZSH_VERSION:-}" ]; then
# zsh completion needs --flag= prefix
eval "COMPREPLY=( \"\${COMPREPLY[@]/#/${flag}=}\" )"
fi
fi
fi
if [[ -z "${flag_parsing_disabled}" ]]; then
# If flag parsing is enabled, we have completed the flags and can return.
# If flag parsing is disabled, we may not know all (or any) of the flags, so we fallthrough
# to possibly call handle_go_custom_completion.
return 0;
fi
;;
esac
# check if we are handling a flag with special work handling
local index
__%[1]s_index_of_word "${prev}" "${flags_with_completion[@]}"
if [[ ${index} -ge 0 ]]; then
${flags_completion[${index}]}
return
fi
# we are parsing a flag and don't have a special handler, no completion
if [[ ${cur} != "${words[cword]}" ]]; then
return
fi
local completions
completions=("${commands[@]}")
if [[ ${#must_have_one_noun[@]} -ne 0 ]]; then
completions+=("${must_have_one_noun[@]}")
elif [[ -n "${has_completion_function}" ]]; then
# if a go completion function is provided, defer to that function
__%[1]s_handle_go_custom_completion
fi
if [[ ${#must_have_one_flag[@]} -ne 0 ]]; then
completions+=("${must_have_one_flag[@]}")
fi
while IFS='' read -r comp; do
COMPREPLY+=("$comp")
done < <(compgen -W "${completions[*]}" -- "$cur")
if [[ ${#COMPREPLY[@]} -eq 0 && ${#noun_aliases[@]} -gt 0 && ${#must_have_one_noun[@]} -ne 0 ]]; then
while IFS='' read -r comp; do
COMPREPLY+=("$comp")
done < <(compgen -W "${noun_aliases[*]}" -- "$cur")
fi
if [[ ${#COMPREPLY[@]} -eq 0 ]]; then
if declare -F __%[1]s_custom_func >/dev/null; then
# try command name qualified custom func
__%[1]s_custom_func
else
# otherwise fall back to unqualified for compatibility
declare -F __custom_func >/dev/null && __custom_func
fi
fi
# available in bash-completion >= 2, not always present on macOS
if declare -F __ltrim_colon_completions >/dev/null; then
__ltrim_colon_completions "$cur"
fi
# If there is only 1 completion and it is a flag with an = it will be completed
# but we don't want a space after the =
if [[ "${#COMPREPLY[@]}" -eq "1" ]] && [[ $(type -t compopt) = "builtin" ]] && [[ "${COMPREPLY[0]}" == --*= ]]; then
compopt -o nospace
fi
}
# The arguments should be in the form "ext1|ext2|extn"
__%[1]s_handle_filename_extension_flag()
{
local ext="$1"
_filedir "@(${ext})"
}
__%[1]s_handle_subdirs_in_dir_flag()
{
local dir="$1"
pushd "${dir}" >/dev/null 2>&1 && _filedir -d && popd >/dev/null 2>&1 || return
}
__%[1]s_handle_flag()
{
__%[1]s_debug "${FUNCNAME[0]}: c is $c words[c] is ${words[c]}"
# if a command required a flag, and we found it, unset must_have_one_flag()
local flagname=${words[c]}
local flagvalue=""
# if the word contained an =
if [[ ${words[c]} == *"="* ]]; then
flagvalue=${flagname#*=} # take in as flagvalue after the =
flagname=${flagname%%=*} # strip everything after the =
flagname="${flagname}=" # but put the = back
fi
__%[1]s_debug "${FUNCNAME[0]}: looking for ${flagname}"
if __%[1]s_contains_word "${flagname}" "${must_have_one_flag[@]}"; then
must_have_one_flag=()
fi
# if you set a flag which only applies to this command, don't show subcommands
if __%[1]s_contains_word "${flagname}" "${local_nonpersistent_flags[@]}"; then
commands=()
fi
# keep flag value with flagname as flaghash
# flaghash variable is an associative array which is only supported in bash > 3.
if [[ -z "${BASH_VERSION:-}" || "${BASH_VERSINFO[0]:-}" -gt 3 ]]; then
if [ -n "${flagvalue}" ] ; then
flaghash[${flagname}]=${flagvalue}
elif [ -n "${words[ $((c+1)) ]}" ] ; then
flaghash[${flagname}]=${words[ $((c+1)) ]}
else
flaghash[${flagname}]="true" # pad "true" for bool flag
fi
fi
# skip the argument to a two word flag
if [[ ${words[c]} != *"="* ]] && __%[1]s_contains_word "${words[c]}" "${two_word_flags[@]}"; then
__%[1]s_debug "${FUNCNAME[0]}: found a flag ${words[c]}, skip the next argument"
c=$((c+1))
# if we are looking for a flags value, don't show commands
if [[ $c -eq $cword ]]; then
commands=()
fi
fi
c=$((c+1))
}
__%[1]s_handle_noun()
{
__%[1]s_debug "${FUNCNAME[0]}: c is $c words[c] is ${words[c]}"
if __%[1]s_contains_word "${words[c]}" "${must_have_one_noun[@]}"; then
must_have_one_noun=()
elif __%[1]s_contains_word "${words[c]}" "${noun_aliases[@]}"; then
must_have_one_noun=()
fi
nouns+=("${words[c]}")
c=$((c+1))
}
__%[1]s_handle_command()
{
__%[1]s_debug "${FUNCNAME[0]}: c is $c words[c] is ${words[c]}"
local next_command
if [[ -n ${last_command} ]]; then
next_command="_${last_command}_${words[c]//:/__}"
else
if [[ $c -eq 0 ]]; then
next_command="_%[1]s_root_command"
else
next_command="_${words[c]//:/__}"
fi
fi
c=$((c+1))
__%[1]s_debug "${FUNCNAME[0]}: looking for ${next_command}"
declare -F "$next_command" >/dev/null && $next_command
}
__%[1]s_handle_word()
{
if [[ $c -ge $cword ]]; then
__%[1]s_handle_reply
return
fi
__%[1]s_debug "${FUNCNAME[0]}: c is $c words[c] is ${words[c]}"
if [[ "${words[c]}" == -* ]]; then
__%[1]s_handle_flag
elif __%[1]s_contains_word "${words[c]}" "${commands[@]}"; then
__%[1]s_handle_command
elif [[ $c -eq 0 ]]; then
__%[1]s_handle_command
elif __%[1]s_contains_word "${words[c]}" "${command_aliases[@]}"; then
# aliashash variable is an associative array which is only supported in bash > 3.
if [[ -z "${BASH_VERSION:-}" || "${BASH_VERSINFO[0]:-}" -gt 3 ]]; then
words[c]=${aliashash[${words[c]}]}
__%[1]s_handle_command
else
__%[1]s_handle_noun
fi
else
__%[1]s_handle_noun
fi
__%[1]s_handle_word
}
`, name, ShellCompNoDescRequestCmd,
ShellCompDirectiveError, ShellCompDirectiveNoSpace, ShellCompDirectiveNoFileComp,
ShellCompDirectiveFilterFileExt, ShellCompDirectiveFilterDirs, activeHelpEnvVar(name)))
}
func writePostscript(buf io.StringWriter, name string) {
name = strings.ReplaceAll(name, ":", "__")
WriteStringAndCheck(buf, fmt.Sprintf("__start_%s()\n", name))
WriteStringAndCheck(buf, fmt.Sprintf(`{
local cur prev words cword split
declare -A flaghash 2>/dev/null || :
declare -A aliashash 2>/dev/null || :
if declare -F _init_completion >/dev/null 2>&1; then
_init_completion -s || return
else
__%[1]s_init_completion -n "=" || return
fi
local c=0
local flag_parsing_disabled=
local flags=()
local two_word_flags=()
local local_nonpersistent_flags=()
local flags_with_completion=()
local flags_completion=()
local commands=("%[1]s")
local command_aliases=()
local must_have_one_flag=()
local must_have_one_noun=()
local has_completion_function=""
local last_command=""
local nouns=()
local noun_aliases=()
__%[1]s_handle_word
}
`, name))
WriteStringAndCheck(buf, fmt.Sprintf(`if [[ $(type -t compopt) = "builtin" ]]; then
complete -o default -F __start_%s %s
else
complete -o default -o nospace -F __start_%s %s
fi
`, name, name, name, name))
WriteStringAndCheck(buf, "# ex: ts=4 sw=4 et filetype=sh\n")
}
func writeCommands(buf io.StringWriter, cmd *Command) {
WriteStringAndCheck(buf, " commands=()\n")
for _, c := range cmd.Commands() {
if !c.IsAvailableCommand() && c != cmd.helpCommand {
continue
}
WriteStringAndCheck(buf, fmt.Sprintf(" commands+=(%q)\n", c.Name()))
writeCmdAliases(buf, c)
}
WriteStringAndCheck(buf, "\n")
}
func writeFlagHandler(buf io.StringWriter, name string, annotations map[string][]string, cmd *Command) {
for key, value := range annotations {
switch key {
case BashCompFilenameExt:
WriteStringAndCheck(buf, fmt.Sprintf(" flags_with_completion+=(%q)\n", name))
var ext string
if len(value) > 0 {
ext = fmt.Sprintf("__%s_handle_filename_extension_flag ", cmd.Root().Name()) + strings.Join(value, "|")
} else {
ext = "_filedir"
}
WriteStringAndCheck(buf, fmt.Sprintf(" flags_completion+=(%q)\n", ext))
case BashCompCustom:
WriteStringAndCheck(buf, fmt.Sprintf(" flags_with_completion+=(%q)\n", name))
if len(value) > 0 {
handlers := strings.Join(value, "; ")
WriteStringAndCheck(buf, fmt.Sprintf(" flags_completion+=(%q)\n", handlers))
} else {
WriteStringAndCheck(buf, " flags_completion+=(:)\n")
}
case BashCompSubdirsInDir:
WriteStringAndCheck(buf, fmt.Sprintf(" flags_with_completion+=(%q)\n", name))
var ext string
if len(value) == 1 {
ext = fmt.Sprintf("__%s_handle_subdirs_in_dir_flag ", cmd.Root().Name()) + value[0]
} else {
ext = "_filedir -d"
}
WriteStringAndCheck(buf, fmt.Sprintf(" flags_completion+=(%q)\n", ext))
}
}
}
const cbn = "\")\n"
func writeShortFlag(buf io.StringWriter, flag *pflag.Flag, cmd *Command) {
name := flag.Shorthand
format := " "
if len(flag.NoOptDefVal) == 0 {
format += "two_word_"
}
format += "flags+=(\"-%s" + cbn
WriteStringAndCheck(buf, fmt.Sprintf(format, name))
writeFlagHandler(buf, "-"+name, flag.Annotations, cmd)
}
func writeFlag(buf io.StringWriter, flag *pflag.Flag, cmd *Command) {
name := flag.Name
format := " flags+=(\"--%s"
if len(flag.NoOptDefVal) == 0 {
format += "="
}
format += cbn
WriteStringAndCheck(buf, fmt.Sprintf(format, name))
if len(flag.NoOptDefVal) == 0 {
format = " two_word_flags+=(\"--%s" + cbn
WriteStringAndCheck(buf, fmt.Sprintf(format, name))
}
writeFlagHandler(buf, "--"+name, flag.Annotations, cmd)
}
func writeLocalNonPersistentFlag(buf io.StringWriter, flag *pflag.Flag) {
name := flag.Name
format := " local_nonpersistent_flags+=(\"--%[1]s" + cbn
if len(flag.NoOptDefVal) == 0 {
format += " local_nonpersistent_flags+=(\"--%[1]s=" + cbn
}
WriteStringAndCheck(buf, fmt.Sprintf(format, name))
if len(flag.Shorthand) > 0 {
WriteStringAndCheck(buf, fmt.Sprintf(" local_nonpersistent_flags+=(\"-%s\")\n", flag.Shorthand))
}
}
// prepareCustomAnnotationsForFlags setup annotations for go completions for registered flags
func prepareCustomAnnotationsForFlags(cmd *Command) {
flagCompletionMutex.RLock()
defer flagCompletionMutex.RUnlock()
for flag := range flagCompletionFunctions {
// Make sure the completion script calls the __*_go_custom_completion function for
// every registered flag. We need to do this here (and not when the flag was registered
// for completion) so that we can know the root command name for the prefix
// of __<prefix>_go_custom_completion
if flag.Annotations == nil {
flag.Annotations = map[string][]string{}
}
flag.Annotations[BashCompCustom] = []string{fmt.Sprintf("__%[1]s_handle_go_custom_completion", cmd.Root().Name())}
}
}
func writeFlags(buf io.StringWriter, cmd *Command) {
prepareCustomAnnotationsForFlags(cmd)
WriteStringAndCheck(buf, ` flags=()
two_word_flags=()
local_nonpersistent_flags=()
flags_with_completion=()
flags_completion=()
`)
if cmd.DisableFlagParsing {
WriteStringAndCheck(buf, " flag_parsing_disabled=1\n")
}
localNonPersistentFlags := cmd.LocalNonPersistentFlags()
cmd.NonInheritedFlags().VisitAll(func(flag *pflag.Flag) {
if nonCompletableFlag(flag) {
return
}
writeFlag(buf, flag, cmd)
if len(flag.Shorthand) > 0 {
writeShortFlag(buf, flag, cmd)
}
// localNonPersistentFlags are used to stop the completion of subcommands when one is set
// if TraverseChildren is true we should allow to complete subcommands
if localNonPersistentFlags.Lookup(flag.Name) != nil && !cmd.Root().TraverseChildren {
writeLocalNonPersistentFlag(buf, flag)
}
})
cmd.InheritedFlags().VisitAll(func(flag *pflag.Flag) {
if nonCompletableFlag(flag) {
return
}
writeFlag(buf, flag, cmd)
if len(flag.Shorthand) > 0 {
writeShortFlag(buf, flag, cmd)
}
})
WriteStringAndCheck(buf, "\n")
}
func writeRequiredFlag(buf io.StringWriter, cmd *Command) {
WriteStringAndCheck(buf, " must_have_one_flag=()\n")
flags := cmd.NonInheritedFlags()
flags.VisitAll(func(flag *pflag.Flag) {
if nonCompletableFlag(flag) {
return
}
for key := range flag.Annotations {
switch key {
case BashCompOneRequiredFlag:
format := " must_have_one_flag+=(\"--%s"
if flag.Value.Type() != "bool" {
format += "="
}
format += cbn
WriteStringAndCheck(buf, fmt.Sprintf(format, flag.Name))
if len(flag.Shorthand) > 0 {
WriteStringAndCheck(buf, fmt.Sprintf(" must_have_one_flag+=(\"-%s"+cbn, flag.Shorthand))
}
}
}
})
}
func writeRequiredNouns(buf io.StringWriter, cmd *Command) {
WriteStringAndCheck(buf, " must_have_one_noun=()\n")
sort.Strings(cmd.ValidArgs)
for _, value := range cmd.ValidArgs {
// Remove any description that may be included following a tab character.
// Descriptions are not supported by bash completion.
value = strings.Split(value, "\t")[0]
WriteStringAndCheck(buf, fmt.Sprintf(" must_have_one_noun+=(%q)\n", value))
}
if cmd.ValidArgsFunction != nil {
WriteStringAndCheck(buf, " has_completion_function=1\n")
}
}
func writeCmdAliases(buf io.StringWriter, cmd *Command) {
if len(cmd.Aliases) == 0 {
return
}
sort.Strings(cmd.Aliases)
WriteStringAndCheck(buf, fmt.Sprint(` if [[ -z "${BASH_VERSION:-}" || "${BASH_VERSINFO[0]:-}" -gt 3 ]]; then`, "\n"))
for _, value := range cmd.Aliases {
WriteStringAndCheck(buf, fmt.Sprintf(" command_aliases+=(%q)\n", value))
WriteStringAndCheck(buf, fmt.Sprintf(" aliashash[%q]=%q\n", value, cmd.Name()))
}
WriteStringAndCheck(buf, ` fi`)
WriteStringAndCheck(buf, "\n")
}
func writeArgAliases(buf io.StringWriter, cmd *Command) {
WriteStringAndCheck(buf, " noun_aliases=()\n")
sort.Strings(cmd.ArgAliases)
for _, value := range cmd.ArgAliases {
WriteStringAndCheck(buf, fmt.Sprintf(" noun_aliases+=(%q)\n", value))
}
}
func gen(buf io.StringWriter, cmd *Command) {
for _, c := range cmd.Commands() {
if !c.IsAvailableCommand() && c != cmd.helpCommand {
continue
}
gen(buf, c)
}
commandName := cmd.CommandPath()
commandName = strings.ReplaceAll(commandName, " ", "_")
commandName = strings.ReplaceAll(commandName, ":", "__")
if cmd.Root() == cmd {
WriteStringAndCheck(buf, fmt.Sprintf("_%s_root_command()\n{\n", commandName))
} else {
WriteStringAndCheck(buf, fmt.Sprintf("_%s()\n{\n", commandName))
}
WriteStringAndCheck(buf, fmt.Sprintf(" last_command=%q\n", commandName))
WriteStringAndCheck(buf, "\n")
WriteStringAndCheck(buf, " command_aliases=()\n")
WriteStringAndCheck(buf, "\n")
writeCommands(buf, cmd)
writeFlags(buf, cmd)
writeRequiredFlag(buf, cmd)
writeRequiredNouns(buf, cmd)
writeArgAliases(buf, cmd)
WriteStringAndCheck(buf, "}\n\n")
}
// GenBashCompletion generates bash completion file and writes to the passed writer.
func (c *Command) GenBashCompletion(w io.Writer) error {
buf := new(bytes.Buffer)
writePreamble(buf, c.Name())
if len(c.BashCompletionFunction) > 0 {
buf.WriteString(c.BashCompletionFunction + "\n")
}
gen(buf, c)
writePostscript(buf, c.Name())
_, err := buf.WriteTo(w)
return err
}
func nonCompletableFlag(flag *pflag.Flag) bool {
return flag.Hidden || len(flag.Deprecated) > 0
}
// GenBashCompletionFile generates bash completion file.
func (c *Command) GenBashCompletionFile(filename string) error {
outFile, err := os.Create(filename)
if err != nil {
return err
}
defer outFile.Close()
return c.GenBashCompletion(outFile)
}