GShell 0.1.2 − 動くソースコード

開発:ソースコードだって能動的に主張するべきだということで、動くソースコードを作ってみました。

基盤:てか、コメント内のJavaScriptがブラウザで実行されてるだけですよねw

開発:いやいや、たとえばJavaScriptでGoの処理系を書けば話は変わってきますよ。完全な処理系で無くてもいいんで。あるはGoでブラウザを作る。既存の資産はそのまま使って、Goと動的リンクするでも良いと思います。

社長:変更履歴とかコメント付けとか、プログラミング言語自身てサポートしてないでんですよね。たとえばWordでプログラムを書くと良いかも。

基盤:マークアップを想定した構文があると良いのでしょうかね。

開発:頭から尻尾まで自分の言語で書いてないと怒るというのが心が狭いといいいますか。ざーっとした文章の中でこの部分は自分の理解できる言語だなと思ったらそこを処理する。それまでの情報は文脈として利用するとかしたら良いと思いますね。昔、埋込み型のSQLだったか、そんな感じになってたような。

社長:そもそも自分自身がどう書かれているかも普通の言語のプログラムは知らないですしね。

開発:それはそうと、これをやってて幾つか面白いことがわかりました。この流れていくGShellのロゴはdata URIで埋め込んであるのですが、base64エンコーディングして8KBを超えています。すると、ロゴの底の部分が切れる。おそらく8KBまでで切るという規約か、共通の実装のせいかと思います。ですが、途中で画像データが切れているのに、エラーにはしないで表示している。。。と思ったのですが、私がbase64にする時に末尾をちょん切ってました。そのような制限は無いようです (^-^; 治りました。

社長:しかし、base64エンコーディングがライブラリにあるなんて良い時代ですね。MIMEが出来た当時は自作したものです。

開発:でも何故か、base64にするときに一行の長さを制約して折り返すというオプションが無いようなんです。不思議。MIMEを想定してないんですかね。そのせいで無駄な憶測をしてしまいました。

社長:言語によって、文字列定数の長さ制限が厳しかったりしますよね。昔はCで結構苦労しました。2KBとか?

開発:JavaScriptは全然楽勝ですね。まあ、長大なHTMLを生成しちゃう言語ですからねえ。ただ、JavaScriptっていうと自動生成されたか何かで改行もなくごちゃっと詰め込まれているのをよく見るので、改行の概念が無いようなイメージを持っていたんですが、ちゃんと文字列定数の途中を改行で分けるときには行末にバックスラッシュを入れれば良いということが分かりました。ごく普通の言語なんですね。// で行末までコメントというのも、大変助かります。

開発:最初はCSSのurl()の中に長大なdata uri を入れるのに、改行を入れたのですが、やはりそのせいでダメ。HTMLは行末にバックスラッシュが無くてもクォーテーションが終わるまで読んでくれるので、そのへんの流儀が違うのが、そもそも生まれ育ち志向が違うんだろうなという感じはします。

社長:ゼロから同時に、HTML的+CSS的+JavaScript的一体言語を作り直したら、どういうものになるでしょうね。

基盤:HTMLとCSSとJavaScriptとの間の属性名の関係とか面倒くさいですよね。一つの言語なら良いのに。

開発:実際3者の処理系は長年かけてとてもリッチに整備されて来ているわけで、それらをもっと簡単にまとめて書ける言語の皮をかぶせることはできそうに思いますね。

開発:ああそれで、5+1大ブラウザで試したわけですが、なぜか左下のSafariが表示してくれない。

開発:Safariのdata URIの処理に問題があるのだろうかと、この時は思ったんですが、どうやらちょん切れたPNGファイルを表示するのを拒否したようです。さっき直したのを食わせたらちゃんと動きました。

社長:ストイックなんですかね。狭量なんですかね。

開発:あともう一点は、favicon の扱いです。これはlink relで書いているのですが、なぜか上の集合写真にあるように Firefox しか表示してくれない。

開発:なんでかと思ったら、どうもこの Goのコードに無理やりHTMLのフリをさせるために入れているコメント記号が邪魔をしているようなんです。この // やら /* をはずしてやれば、他のブラウザでもちゃんと見てくれます。

社長:ノイズに強く作るかどうか、その是非はあるでしょうね。もとのHTMLはめっちゃノイズに強かった。

開発:あとは、この下のコードのようにWordPressに張り込むとJavaScrptが動かないという謎。インラインのスクリプトが動かなくなるような仕掛けでもあるんでしょうかね?

社長:まあお仕着せのブログサーバですからねぇ…

— 2020-0817 SatoxITS

// /* GShell-0.1.3 by SatoxITS

GShell // a General purpose Shell built on the top of Golang

*/ /*
Overview
To be written
*/ /*
Index

Implementation
	Structures
		import
		struct
	Main functions
		str-expansion	// macro processor
		finder		// builtin find + du
		grep		// builtin grep + wc + cksum + ...
		plugin		// plugin commands
		system		// external commands
		builtin		// builtin commands
		network		// socket handler
		redirect	// StdIn/Out redireciton
		history		// command history
		rusage		// resouce usage
		encode		// encode / decode
		getline		// line editor
		interpreter	// command interpreter
		main
*/ //
Source Code //
// gsh - Go lang based Shell
// (c) 2020 ITS more Co., Ltd.
// 2020-0807 created by SatoxITS (sato@its-more.jp)

package main // gsh main
// Imported packages // Packages
import (
	"fmt"		// fmt
	"strings"	// strings
	"strconv"	// strconv
	"sort"		// sort
	"time"		// time
	"bufio"		// bufio
	"io/ioutil"	// ioutil
	"os"		// os
	"syscall"	// syscall
	"plugin"	// plugin
	"net"		// net
	"net/http"	// http
	//"html"	// html
	"path/filepath"	// filepath
	"go/types"	// types
	"go/token"	// token
	"encoding/base64"	// base64
	//"gshdata"	// gshell's logo and source code
)

var NAME = "gsh"
var VERSION = "0.1.3"
var DATE = "2020-0817b"
var LINESIZE = (8*1024)
var PATHSEP = ":"	// should be ";" in Windows
var DIRSEP = "/"	// canbe \ in Windows
var GSH_HOME = ".gsh"	// under home directory
var PROMPT = "> "

// -xX logging control
// --A-- all
// --I-- info.
// --D-- debug
// --W-- warning
// --E-- error
// --F-- fatal error

// Structures
type GCommandHistory struct {
	StartAt		time.Time // command line execution started at
	EndAt		time.Time // command line execution ended at
	ResCode		int       // exit code of (external command)
	CmdError	error     // error string
	OutData		*os.File  // output of the command
	FoundFile	[]string  // output - result of ufind
	Rusagev		[2]syscall.Rusage // Resource consumption, CPU time or so
	CmdId		int       // maybe with identified with arguments or impact
			          // redireciton commands should not be the CmdId
	WorkDir		string    // working directory at start
	CmdLine		string    // command line
}
type GChdirHistory struct {
	Dir		string
	MovedAt		time.Time
}
type CmdMode struct {
	BackGround	bool
}
type PluginInfo struct {
	Spec		*plugin.Plugin
	Addr		plugin.Symbol
	Name		string // maybe relative
	Path		string // this is in Plugin but hidden
}
type GshContext struct {
	StartDir	string	// the current directory at the start
	GetLine		string	// gsh-getline command as a input line editor
	ChdirHistory	[]GChdirHistory // the 1st entry is wd at the start
	gshPA		syscall.ProcAttr
	CommandHistory	[]GCommandHistory
	CmdCurrent	GCommandHistory
	BackGround	bool
	BackGroundJobs	[]int
	LastRusage	syscall.Rusage
	GshHomeDir	string
	TerminalId	int
	CmdTrace	bool
	PluginFuncs	[]PluginInfo
}

func strBegins(str, pat string)(bool){
	if 0 < len(str){
		yes := str[0:len(pat)] == pat
		//fmt.Printf("--D-- strBegins(%v,%v)=%v\n",str,pat,yes)
		return yes
	}
	//fmt.Printf("--D-- strBegins(%v,%v)=%v\n",str,pat,false)
	return false
}
func isin(what string, list []string) bool {
	for _, v := range list  {
		if v == what {
			return true
		}
	}
	return false
}
func isinX(what string,list[]string)(int){
	for i,v := range list {
		if v == what {
			return i
		}
	}
	return -1
}

func env(opts []string) {
	env := os.Environ()
	if isin("-s", opts){
		sort.Slice(env, func(i,j int) bool {
			return env[i] < env[j]
		})
	}
	for _, v := range env {
		fmt.Printf("%v\n",v)
	}
}

// - rewriting should be context dependent
// - should postpone until the real point of evaluation
// - should rewrite only known notation of symobl
func scanInt(str string)(val int,leng int){
	leng = -1
	for i,ch := range str {
		if '0' <= ch && ch <= '9' {
			leng = i+1
		}else{
			break
		}
	}
	if 0 < leng {
		ival,_ := strconv.Atoi(str[0:leng])
		return ival,leng
	}else{
		return 0,0
	}
}
func substHistory(gshCtx *GshContext,str string,i int,rstr string)(leng int,rst string){
	if len(str[i+1:]) == 0 {
		return 0,rstr
	}
	hi := 0
	histlen := len(gshCtx.CommandHistory)
	if str[i+1] == '!' {
		hi = histlen - 1
		leng = 1
	}else{
		hi,leng = scanInt(str[i+1:])
		if leng == 0 {
			return 0,rstr
		}
		if hi < 0 {
			hi = histlen + hi
		}
	}
	if 0 <= hi && hi < histlen {
		//fmt.Printf("--D-- %v(%c)\n",str[i+leng:],str[i+leng])
		if 1 < len(str[i+leng:]) && str[i+leng:][1] == 'f' {
			leng += 1
			xlist := []string{}
			list := gshCtx.CommandHistory[hi].FoundFile
			for _,v := range list {
				//list[i] = escapeWhiteSP(v)
				xlist = append(xlist,escapeWhiteSP(v))
			}
			//rstr += strings.Join(list," ")
			rstr += strings.Join(xlist," ")
		}else{
			rstr += gshCtx.CommandHistory[hi].CmdLine
		}
	}else{
		leng = 0
	}
	return leng,rstr
}
func escapeWhiteSP(str string)(string){
	if len(str) == 0 {
		return "\\z" // empty, to be ignored
	}
	rstr := ""
	for _,ch := range str {
		switch ch {
			case '\\': rstr += "\\\\"
			case ' ': rstr += "\\s"
			case '\t': rstr += "\\t"
			case '\r': rstr += "\\r"
			case '\n': rstr += "\\n"
			default: rstr += string(ch)
		}
	}
	return rstr
}
func unescapeWhiteSP(str string)(string){ // strip original escapes
	rstr := ""
	for i := 0; i < len(str); i++ {
		ch := str[i]
		if ch == '\\' {
			if i+1 < len(str) {
				switch str[i+1] {
					case 'z':
						continue;
				}
			}
		}
		rstr += string(ch)
	}
	return rstr
}
func unescapeWhiteSPV(strv []string)([]string){ // strip original escapes
	ustrv := []string{}
	for _,v := range strv {
		ustrv = append(ustrv,unescapeWhiteSP(v))
	}
	return ustrv
}

// str-expansion
// - this should be a macro processor
func strsubst(gshCtx *GshContext,str string,histonly bool) string {
	rstr := ""
	inEsc := 0 // escape characer mode 
	for i := 0; i < len(str); i++ {
		//fmt.Printf("--D--Subst %v:%v\n",i,str[i:])
		ch := str[i]
		if inEsc == 0 {
			if ch == '!' {
				leng,xrstr := substHistory(gshCtx,str,i,rstr)
				if 0 < leng {
					i += leng
					rstr = xrstr
					continue
				}
			}
			switch ch {
				case '\\': inEsc = '\\'; continue
				case '%':  inEsc = '%';  continue
				case '$':
			}
		}
		switch inEsc {
		case '\\':
			switch ch {
				case '\\': ch = '\\'
				case 's': ch = ' '
				case 't': ch = '\t'
				case 'r': ch = '\r'
				case 'n': ch = '\n'
				case 'z': inEsc = 0; continue // empty, to be ignored
			}
			inEsc = 0 
		case '%':
			switch {
				case ch == '%': ch = '%'
				case ch == 'T':
					rstr = rstr + time.Now().Format(time.Stamp)
					continue;
				default:
					// postpone the interpretation
					rstr = rstr + "%" + string(ch)
					continue;
			}
			inEsc = 0
		}
		rstr = rstr + string(ch)
	}
	return rstr
}
func showFileInfo(path string, opts []string) {
	if isin("-l",opts) || isin("-ls",opts) {
		fi, _ := os.Stat(path)
		mod := fi.ModTime()
		date := mod.Format(time.Stamp)
		fmt.Printf("%v %8v %s ",fi.Mode(),fi.Size(),date)
	}
	fmt.Printf("%s",path)
	if isin("-sp",opts) {
		fmt.Printf(" ")
	}else
	if ! isin("-n",opts) {
		fmt.Printf("\n")
	}
}
func userHomeDir()(string,bool){
	/*
	homedir,_ = os.UserHomeDir() // not implemented in older Golang
	*/
	homedir,found := os.LookupEnv("HOME")
	//fmt.Printf("--I-- HOME=%v(%v)\n",homedir,found)
	if !found {
		return "/tmp",found
	}
	return homedir,found
}

func toFullpath(path string) (fullpath string) {
	if path[0] == '/' {
		return path
	}
	pathv := strings.Split(path,DIRSEP)
	switch {
	case pathv[0] == ".":
		pathv[0], _ = os.Getwd()
	case pathv[0] == "..": // all ones should be interpreted
		cwd, _ := os.Getwd()
		ppathv := strings.Split(cwd,DIRSEP)
		pathv[0] = strings.Join(ppathv,DIRSEP)
	case pathv[0] == "~":
		pathv[0],_ = userHomeDir()
	default:
		cwd, _ := os.Getwd()
		pathv[0] = cwd + DIRSEP + pathv[0]
	}
	return strings.Join(pathv,DIRSEP)
}

func IsRegFile(path string)(bool){
	fi, err := os.Stat(path)
	if err == nil {
		fm := fi.Mode()
		return fm.IsRegular();
	}
	return false
}

// Encode / Decode
// Encoder
func Enc(gshCtx *GshContext,argv[]string)(*GshContext){
	file := os.Stdin
	buff := make([]byte,LINESIZE)
	li := 0
	encoder := base64.NewEncoder(base64.StdEncoding,os.Stdout)	
	for li = 0; ; li++ {
		count, err := file.Read(buff)
		if count <= 0 {
			break
		}
		if err != nil {
			break
		}
		encoder.Write(buff[0:count])
	}
	encoder.Close()
	return gshCtx
}
func Dec(gshCtx *GshContext,argv[]string)(*GshContext){
	decoder := base64.NewDecoder(base64.StdEncoding,os.Stdin)	
	li := 0
	buff := make([]byte,LINESIZE)
	for li = 0; ; li++ {
		count, err := decoder.Read(buff)
		if count <= 0 {
			break
		}
		if err != nil {
			break
		}
		os.Stdout.Write(buff[0:count])
	}
	return gshCtx
}
// lnsp [N] [-crlf][-C \\]
func SplitLine(gshCtx *GshContext,argv[]string)(*GshContext){
	reader := bufio.NewReaderSize(os.Stdin,64*1024)
	ni := 0
	toi := 0
	for ni = 0; ; ni++ {
		line, err := reader.ReadString('\n')
		if len(line) <= 0 {
			if err != nil {
			fmt.Fprintf(os.Stderr,"--I-- lnsp %d to %d (%v)\n",ni,toi,err)
			break
			}
		}
		off := 0
		ilen := len(line)
		remlen := len(line)
		for oi := 0; 0 < remlen; oi++ {
			olen := remlen
			addnl := false
			if 72 < olen {
				olen = 72
				addnl = true
			}
			fmt.Fprintf(os.Stderr,"--D-- write %d [%d.%d] %d %d/%d/%d\n",
				toi,ni,oi,off,olen,remlen,ilen)
			toi += 1
			os.Stdout.Write([]byte(line[0:olen]))
			if addnl {
				//os.Stdout.Write([]byte("\r\n"))
				os.Stdout.Write([]byte("\n"))
			}
			line = line[olen:]
			off += olen
			remlen -= olen
		}
	}
	fmt.Fprintf(os.Stderr,"--I-- lnsp %d to %d\n",ni,toi)
	return gshCtx
}

// grep
// "lines", "lin" or "lnp" for "(text) line processor" or "scanner"
// a*,!ab,c, ... sequentioal combination of patterns
// what "LINE" is should be definable
// generic line-by-line processing
// grep [-v]
// cat -n -v
// uniq [-c]
// tail -f
// sed s/x/y/ or awk
// grep with line count like wc
// rewrite contents if specified
func xGrep(gshCtx GshContext,path string,rexpv[]string)(int){
	file, err := os.OpenFile(path,os.O_RDONLY,0)
	if err != nil {
		fmt.Printf("--E-- grep %v (%v)\n",path,err)
		return -1
	}
	defer file.Close()
	if gshCtx.CmdTrace { fmt.Printf("--I-- grep %v %v\n",path,rexpv) }
	//reader := bufio.NewReaderSize(file,LINESIZE)
	reader := bufio.NewReaderSize(file,80)
	li := 0
	found := 0
	for li = 0; ; li++ {
		line, err := reader.ReadString('\n')
		if len(line) <= 0 {
			break
		}
		if 150 < len(line) {
			// maybe binary
			break;
		}
		if err != nil {
			break
		}
		if 0 <= strings.Index(string(line),rexpv[0]) {
			found += 1
			fmt.Printf("%s:%d: %s",path,li,line)
		}
	}
		//fmt.Printf("total %d lines %s\n",li,path)
	//if( 0 < found ){ fmt.Printf("((found %d lines %s))\n",found,path); }
	return found
}

// Finder
// finding files with it name and contents
// file names are ORed
// show the content with %x fmt list
// ls -R
// tar command by adding output
type fileSum struct {
	Err	int64	// access error or so
	Size	int64	// content size
	DupSize	int64	// content size from hard links
	Blocks	int64	// number of blocks (of 512 bytes)
	DupBlocks int64	// Blocks pointed from hard links
	HLinks	int64	// hard links
	Words	int64
	Lines	int64
	Files	int64
	Dirs	int64	// the num. of directories
	SymLink	int64
	Flats	int64	// the num. of flat files
	MaxDepth	int64
	MaxNamlen	int64	// max. name length
	nextRepo	time.Time
}
func showFusage(dir string,fusage *fileSum){
	bsume := float64(((fusage.Blocks-fusage.DupBlocks)/2)*1024)/1000000.0
	//bsumdup := float64((fusage.Blocks/2)*1024)/1000000.0

	fmt.Printf("%v: %v files (%vd %vs %vh) %.6f MB (%.2f MBK)\n",
		dir,
		fusage.Files,
		fusage.Dirs,
		fusage.SymLink,
		fusage.HLinks,
		float64(fusage.Size)/1000000.0,bsume);
}
const (
	S_IFMT    = 0170000
	S_IFCHR   = 0020000
	S_IFDIR   = 0040000
	S_IFREG   = 0100000
	S_IFLNK   = 0120000
	S_IFSOCK  = 0140000
)
func cumFinfo(fsum *fileSum, path string, staterr error, fstat syscall.Stat_t, argv[]string,verb bool)(*fileSum){
	now := time.Now()
	if time.Second <= now.Sub(fsum.nextRepo) {
		if !fsum.nextRepo.IsZero(){
			tstmp := now.Format(time.Stamp)
			showFusage(tstmp,fsum)
		}
		fsum.nextRepo = now.Add(time.Second)
	}
	if staterr != nil {
		fsum.Err += 1
		return fsum
	}
	fsum.Files += 1
	if 1 < fstat.Nlink {
		// must count only once...
		// at least ignore ones in the same directory
		//if finfo.Mode().IsRegular() {
		if (fstat.Mode & S_IFMT) == S_IFREG {
			fsum.HLinks += 1
			fsum.DupBlocks += int64(fstat.Blocks)
			//fmt.Printf("---Dup HardLink %v %s\n",fstat.Nlink,path)
		}
	}
	//fsum.Size += finfo.Size()
	fsum.Size += fstat.Size
	fsum.Blocks += int64(fstat.Blocks) 
	//if verb { fmt.Printf("(%8dBlk) %s",fstat.Blocks/2,path) }
	if isin("-ls",argv){
		//if verb { fmt.Printf("%4d %8d ",fstat.Blksize,fstat.Blocks) }
//		fmt.Printf("%d\t",fstat.Blocks/2)
	}
	//if finfo.IsDir()
	if (fstat.Mode & S_IFMT) == S_IFDIR {
		fsum.Dirs += 1
	}
	//if (finfo.Mode() & os.ModeSymlink) != 0 
	if (fstat.Mode & S_IFMT) == S_IFLNK {
		//if verb { fmt.Printf("symlink(%v,%s)\n",fstat.Mode,finfo.Name()) }
		//{ fmt.Printf("symlink(%o,%s)\n",fstat.Mode,finfo.Name()) }
		fsum.SymLink += 1
	}
	return fsum
}
func xxFindEntv(gshCtx GshContext,depth int,total *fileSum,dir string, dstat syscall.Stat_t, ei int, entv []string,npatv[]string,argv[]string)(GshContext,*fileSum){
	nols := isin("-grep",argv)
	// sort entv
	/*
	if isin("-t",argv){
		sort.Slice(filev, func(i,j int) bool {
			return 0 < filev[i].ModTime().Sub(filev[j].ModTime())
		})
	}
	*/
		/*
		if isin("-u",argv){
			sort.Slice(filev, func(i,j int) bool {
				return 0 < filev[i].AccTime().Sub(filev[j].AccTime())
			})
		}
		if isin("-U",argv){
			sort.Slice(filev, func(i,j int) bool {
				return 0 < filev[i].CreatTime().Sub(filev[j].CreatTime())
			})
		}
		*/
	/*
	if isin("-S",argv){
		sort.Slice(filev, func(i,j int) bool {
			return filev[j].Size() < filev[i].Size()
		})
	}
	*/
	for _,filename := range entv {
		for _,npat := range npatv {
			match := true
			if npat == "*" {
				match = true
			}else{
				match, _ = filepath.Match(npat,filename)
			}
			path := dir + DIRSEP + filename
			if !match {
				continue
			}
			var fstat syscall.Stat_t
			staterr := syscall.Lstat(path,&fstat)
			if staterr != nil {
				if !isin("-w",argv){fmt.Printf("ufind: %v\n",staterr) }
				continue;
			}
			if isin("-du",argv) && (fstat.Mode & S_IFMT) == S_IFDIR {
				// should not show size of directory in "-du" mode ...
			}else
			if !nols && !isin("-s",argv) && (!isin("-du",argv) || isin("-a",argv)) {
				if isin("-du",argv) {
					fmt.Printf("%d\t",fstat.Blocks/2)
				}
				showFileInfo(path,argv)
			}
			if true { // && isin("-du",argv)
				total = cumFinfo(total,path,staterr,fstat,argv,false)
			}
			/*
			if isin("-wc",argv) {
			}
			*/
			x := isinX("-grep",argv); // -grep will be convenient like -ls
			if 0 <= x && x+1 <= len(argv) { // -grep will be convenient like -ls
				if IsRegFile(path){
					found := xGrep(gshCtx,path,argv[x+1:])
					if 0 < found {
						foundv := gshCtx.CmdCurrent.FoundFile
						if len(foundv) < 10 {
							gshCtx.CmdCurrent.FoundFile =
							append(gshCtx.CmdCurrent.FoundFile,path)
						}
					}
				}
			}
			if !isin("-r0",argv) { // -d 0 in du, -depth n in find
				//total.Depth += 1
				if (fstat.Mode & S_IFMT) == S_IFLNK {
					continue
				}
				if dstat.Rdev != fstat.Rdev {
					fmt.Printf("--I-- don't follow differnet device %v(%v) %v(%v)\n",
						dir,dstat.Rdev,path,fstat.Rdev)
				}
				if (fstat.Mode & S_IFMT) == S_IFDIR {
					gshCtx,total = xxFind(gshCtx,depth+1,total,path,npatv,argv)
				}
			}
		}
	}
	return gshCtx,total
}
func xxFind(gshCtx GshContext,depth int,total *fileSum,dir string,npatv[]string,argv[]string)(GshContext,*fileSum){
	nols := isin("-grep",argv)
	dirfile,oerr := os.OpenFile(dir,os.O_RDONLY,0)
	if oerr == nil {
		//fmt.Printf("--I-- %v(%v)[%d]\n",dir,dirfile,dirfile.Fd())
		defer dirfile.Close()
	}else{
	}

	prev := *total
	var dstat syscall.Stat_t
	staterr := syscall.Lstat(dir,&dstat) // should be flstat

	if staterr != nil {
		if !isin("-w",argv){ fmt.Printf("ufind: %v\n",staterr) }
		return gshCtx,total
	}
		//filev,err := ioutil.ReadDir(dir)
		//_,err := ioutil.ReadDir(dir) // ReadDir() heavy and bad for huge directory
		/*
		if err != nil {
			if !isin("-w",argv){ fmt.Printf("ufind: %v\n",err) }
			return total
		}
		*/
	if depth == 0 {
		total = cumFinfo(total,dir,staterr,dstat,argv,true)
		if !nols && !isin("-s",argv) && (!isin("-du",argv) || isin("-a",argv)) {
			showFileInfo(dir,argv)
		}
	}
	// it it is not a directory, just scan it and finish

	for ei := 0; ; ei++ {
		entv,rderr := dirfile.Readdirnames(8*1024)
		if len(entv) == 0 || rderr != nil {
			//if rderr != nil { fmt.Printf("[%d] len=%d (%v)\n",ei,len(entv),rderr) }
			break
		}
		if 0 < ei {
			fmt.Printf("--I-- xxFind[%d] %d large-dir: %s\n",ei,len(entv),dir)
		}
		gshCtx,total = xxFindEntv(gshCtx,depth,total,dir,dstat,ei,entv,npatv,argv)
	}
	if isin("-du",argv) {
		// if in "du" mode
		fmt.Printf("%d\t%s\n",(total.Blocks-prev.Blocks)/2,dir)
	}
	return gshCtx,total
}

// {ufind|fu|ls} [Files] [// Names] [-- Expressions]
//  Files is "." by default
//  Names is "*" by default
//  Expressions is "-print" by default for "ufind", or -du for "fu" command
func xFind(gshCtx GshContext,argv[]string)(GshContext){
	if 0 < len(argv) && strBegins(argv[0],"?"){
		showFound(gshCtx,argv)
		return gshCtx
	}
	var total = fileSum{}
	npats := []string{}
	for _,v := range argv {
		if 0 < len(v) && v[0] != '-' {
			npats = append(npats,v)
		}
		if v == "//" { break }
		if v == "--" { break }
		if v == "-grep" { break }
		if v == "-ls" { break }
	}
	if len(npats) == 0 {
		npats = []string{"*"}
	}
	cwd := "."
	// if to be fullpath ::: cwd, _ := os.Getwd()
	if len(npats) == 0 { npats = []string{"*"} }
	gshCtx,fusage := xxFind(gshCtx,0,&total,cwd,npats,argv)
	if !isin("-grep",argv) {
		showFusage("total",fusage)
	}
	return gshCtx
}

func showFiles(files[]string){
	sp := ""
	for i,file := range files {
		if 0 < i { sp = " " } else { sp = "" }
		fmt.Printf(sp+"%s",escapeWhiteSP(file))
	}
}
func showFound(gshCtx GshContext, argv[]string){
	for i,v := range gshCtx.CommandHistory {
		if 0 < len(v.FoundFile) {
			fmt.Printf("!%d (%d) ",i,len(v.FoundFile))
			if isin("-ls",argv){
				fmt.Printf("\n")
				for _,file := range v.FoundFile {
					fmt.Printf("") //sub number?
					showFileInfo(file,argv)
				}
			}else{
				showFiles(v.FoundFile)
				fmt.Printf("\n")
			}
		}
	}
}

func showMatchFile(filev []os.FileInfo, npat,dir string, argv[]string)(string,bool){
	fname := ""
	found := false
	for _,v := range filev {
		match, _ := filepath.Match(npat,(v.Name()))
		if match {
			fname = v.Name()
			found = true
			//fmt.Printf("[%d] %s\n",i,v.Name())
			showIfExecutable(fname,dir,argv)
		}
	}
	return fname,found
}
func showIfExecutable(name,dir string,argv[]string)(ffullpath string,ffound bool){
	var fullpath string
	if strBegins(name,DIRSEP){
		fullpath = name
	}else{
		fullpath = dir + DIRSEP + name
	}
	fi, err := os.Stat(fullpath)
	if err != nil {
		fullpath = dir + DIRSEP + name + ".go"
		fi, err = os.Stat(fullpath)
	}
	if err == nil {
		fm := fi.Mode()
		if fm.IsRegular() {
		  // R_OK=4, W_OK=2, X_OK=1, F_OK=0
		  if syscall.Access(fullpath,5) == nil {
			ffullpath = fullpath
			ffound = true
			if ! isin("-s", argv) {
				showFileInfo(fullpath,argv)
			}
		  }
		}
	}
	return ffullpath, ffound
}
func which(list string, argv []string) (fullpathv []string, itis bool){
	if len(argv) <= 1 {
		fmt.Printf("Usage: which comand [-s] [-a] [-ls]\n")
		return []string{""}, false
	}
	path := argv[1]
	if strBegins(path,"/") {
		// should check if excecutable?
		_,exOK := showIfExecutable(path,"/",argv)
		fmt.Printf("--D-- %v exOK=%v\n",path,exOK)
		return []string{path},exOK
	}
	pathenv, efound := os.LookupEnv(list)
	if ! efound {
		fmt.Printf("--E-- which: no \"%s\" environment\n",list)
		return []string{""}, false
	}
	showall := isin("-a",argv) || 0 <= strings.Index(path,"*")
	dirv := strings.Split(pathenv,PATHSEP)
	ffound := false
	ffullpath := path
	for _, dir := range dirv {
		if 0 <= strings.Index(path,"*") { // by wild-card
			list,_ := ioutil.ReadDir(dir)
			ffullpath, ffound = showMatchFile(list,path,dir,argv)
		}else{
			ffullpath, ffound = showIfExecutable(path,dir,argv)
		}
		//if ffound && !isin("-a", argv) {
		if ffound && !showall {
			break;
		}
	}
	return []string{ffullpath}, ffound
}

func stripLeadingWSParg(argv[]string)([]string){
	for ; 0 < len(argv); {
		if len(argv[0]) == 0 {
			argv = argv[1:]
		}else{
			break
		}
	}
	return argv
}
func xEval(argv []string, nlend bool){
	argv = stripLeadingWSParg(argv)
	if len(argv) == 0 {
		fmt.Printf("eval [%%format] [Go-expression]\n")
		return
	}
	pfmt := "%v"
	if argv[0][0] == '%' {
		pfmt = argv[0]
		argv = argv[1:]
	}
	if len(argv) == 0 {
		return
	}
	gocode := strings.Join(argv," ");
	//fmt.Printf("eval [%v] [%v]\n",pfmt,gocode)
	fset := token.NewFileSet()
	rval, _ := types.Eval(fset,nil,token.NoPos,gocode)
	fmt.Printf(pfmt,rval.Value)
	if nlend { fmt.Printf("\n") }
}

func getval(name string) (found bool, val int) {
	/* should expand the name here */
	if name == "gsh.pid" {
		return true, os.Getpid()
	}else
	if name == "gsh.ppid" {
		return true, os.Getppid()
	}
	return false, 0
}

func echo(argv []string, nlend bool){
	for ai := 1; ai < len(argv); ai++ {
		if 1 < ai {
			fmt.Printf(" ");
		}
		arg := argv[ai]
		found, val := getval(arg)
		if found {
			fmt.Printf("%d",val)
		}else{
			fmt.Printf("%s",arg)
		}
	}
	if nlend {
		fmt.Printf("\n");
	}
}

func resfile() string {
	return "gsh.tmp"
}
//var resF *File
func resmap() {
	//_ , err := os.OpenFile(resfile(), os.O_RDWR|os.O_CREATE, os.ModeAppend)
	// https://developpaper.com/solution-to-golang-bad-file-descriptor-problem/
	_ , err := os.OpenFile(resfile(), os.O_RDWR|os.O_CREATE, 0600)
	if err != nil {
		fmt.Printf("refF could not open: %s\n",err)
	}else{
		fmt.Printf("refF opened\n")
	}
}

// External commands
func excommand(gshCtx GshContext, exec bool, argv []string) (GshContext, bool) {
	if gshCtx.CmdTrace { fmt.Printf("--I-- excommand[%v](%v)\n",exec,argv) }

	gshPA := gshCtx.gshPA
	fullpathv, itis := which("PATH",[]string{"which",argv[0],"-s"})
	if itis == false {
		return gshCtx, true
	}
	fullpath := fullpathv[0]
	argv = unescapeWhiteSPV(argv)
	if 0 < strings.Index(fullpath,".go") {
		nargv := argv // []string{}
		gofullpathv, itis := which("PATH",[]string{"which","go","-s"})
		if itis == false {
			fmt.Printf("--F-- Go not found\n")
			return gshCtx, true
		}
		gofullpath := gofullpathv[0]
		nargv = []string{ gofullpath, "run", fullpath }
		fmt.Printf("--I-- %s {%s %s %s}\n",gofullpath,
			nargv[0],nargv[1],nargv[2])
		if exec {
			syscall.Exec(gofullpath,nargv,os.Environ())
		}else{
			pid, _ := syscall.ForkExec(gofullpath,nargv,&gshPA)
			if gshCtx.BackGround {
				fmt.Printf("--I-- in Background [%d]\n",pid)
				gshCtx.BackGroundJobs = append(gshCtx.BackGroundJobs,pid)
			}else{
				rusage := syscall.Rusage {}
				syscall.Wait4(pid,nil,0,&rusage)
				gshCtx.LastRusage = rusage
				gshCtx.CmdCurrent.Rusagev[1] = rusage
			}
		}
	}else{
		if exec {
			syscall.Exec(fullpath,argv,os.Environ())
		}else{
			pid, _ := syscall.ForkExec(fullpath,argv,&gshPA)
			//fmt.Printf("[%d]\n",pid); // '&' to be background
			if gshCtx.BackGround {
				fmt.Printf("--I-- in Background [%d]\n",pid)
				gshCtx.BackGroundJobs = append(gshCtx.BackGroundJobs,pid)
			}else{
				rusage := syscall.Rusage {}
				syscall.Wait4(pid,nil,0,&rusage);
				gshCtx.LastRusage = rusage
				gshCtx.CmdCurrent.Rusagev[1] = rusage
			}
		}
	}
	return gshCtx, false
}

// Builtin Commands
func sleep(gshCtx GshContext, argv []string) {
	if len(argv) < 2 {
		fmt.Printf("Sleep 100ms, 100us, 100ns, ...\n")
		return
	}
	duration := argv[1];
	d, err := time.ParseDuration(duration)
	if err != nil {
		d, err = time.ParseDuration(duration+"s")
		if err != nil {
			fmt.Printf("duration ? %s (%s)\n",duration,err)
			return
		}
	}
	//fmt.Printf("Sleep %v\n",duration)
	time.Sleep(d)
	if 0 < len(argv[2:]) {
		gshellv(gshCtx, argv[2:])
	}
}
func repeat(gshCtx GshContext, argv []string) {
	if len(argv) < 2 {
		return
	}
	start0 := time.Now()
	for ri,_ := strconv.Atoi(argv[1]); 0 < ri; ri-- {
		if 0 < len(argv[2:]) {
			//start := time.Now()
			gshellv(gshCtx, argv[2:])
			end := time.Now()
			elps := end.Sub(start0);
			if( 1000000000 < elps ){
				fmt.Printf("(repeat#%d %v)\n",ri,elps);
			}
		}
	}
}

func gen(gshCtx GshContext, argv []string) {
	gshPA := gshCtx.gshPA
	if len(argv) < 2 {
		fmt.Printf("Usage: %s N\n",argv[0])
		return
	}
	// should br repeated by "repeat" command
	count, _ := strconv.Atoi(argv[1])
	fd := gshPA.Files[1] // Stdout
	file := os.NewFile(fd,"internalStdOut")
	fmt.Printf("--I-- Gen. Count=%d to [%d]\n",count,file.Fd())
	//buf := []byte{}
	outdata := "0123 5678 0123 5678 0123 5678 0123 5678\r"
	for gi := 0; gi < count; gi++ {
		file.WriteString(outdata)
	}
	//file.WriteString("\n")
	fmt.Printf("\n(%d B)\n",count*len(outdata));
	//file.Close()
}

// network
// -s, -si, -so // bi-directional, source, sync (maybe socket)
func sconnect(gshCtx GshContext, inTCP bool, argv []string) {
	gshPA := gshCtx.gshPA
	if len(argv) < 2 {
		fmt.Printf("Usage: -s [host]:[port[.udp]]\n")
		return
	}
	remote := argv[1]
	if remote == ":" { remote = "0.0.0.0:9999" }

	if inTCP { // TCP
		dport, err := net.ResolveTCPAddr("tcp",remote);
		if err != nil {
			fmt.Printf("Address error: %s (%s)\n",remote,err)
			return
		}
		conn, err := net.DialTCP("tcp",nil,dport)
		if err != nil {
			fmt.Printf("Connection error: %s (%s)\n",remote,err)
			return
		}
		file, _ := conn.File();
		fd := file.Fd()
		fmt.Printf("Socket: connected to %s, socket[%d]\n",remote,fd)

		savfd := gshPA.Files[1]
		gshPA.Files[1] = fd;
		gshellv(gshCtx, argv[2:])
		gshPA.Files[1] = savfd
		file.Close()
		conn.Close()
	}else{
		//dport, err := net.ResolveUDPAddr("udp4",remote);
		dport, err := net.ResolveUDPAddr("udp",remote);
		if err != nil {
			fmt.Printf("Address error: %s (%s)\n",remote,err)
			return
		}
		//conn, err := net.DialUDP("udp4",nil,dport)
		conn, err := net.DialUDP("udp",nil,dport)
		if err != nil {
			fmt.Printf("Connection error: %s (%s)\n",remote,err)
			return
		}
		file, _ := conn.File();
		fd := file.Fd()

		ar := conn.RemoteAddr()
		//al := conn.LocalAddr()
		fmt.Printf("Socket: connected to %s [%s], socket[%d]\n",
			remote,ar.String(),fd)

		savfd := gshPA.Files[1]
		gshPA.Files[1] = fd;
		gshellv(gshCtx, argv[2:])
		gshPA.Files[1] = savfd
		file.Close()
		conn.Close()
	}
}
func saccept(gshCtx GshContext, inTCP bool, argv []string) {
	gshPA := gshCtx.gshPA
	if len(argv) < 2 {
		fmt.Printf("Usage: -ac [host]:[port[.udp]]\n")
		return
	}
	local := argv[1]
	if local == ":" { local = "0.0.0.0:9999" }
	if inTCP { // TCP
		port, err := net.ResolveTCPAddr("tcp",local);
		if err != nil {
			fmt.Printf("Address error: %s (%s)\n",local,err)
			return
		}
		//fmt.Printf("Listen at %s...\n",local);
		sconn, err := net.ListenTCP("tcp", port)
		if err != nil {
			fmt.Printf("Listen error: %s (%s)\n",local,err)
			return
		}
		//fmt.Printf("Accepting at %s...\n",local);
		aconn, err := sconn.AcceptTCP()
		if err != nil {
			fmt.Printf("Accept error: %s (%s)\n",local,err)
			return
		}
		file, _ := aconn.File()
		fd := file.Fd()
		fmt.Printf("Accepted TCP at %s [%d]\n",local,fd)

		savfd := gshPA.Files[0]
		gshPA.Files[0] = fd;
		gshellv(gshCtx, argv[2:])
		gshPA.Files[0] = savfd

		sconn.Close();
		aconn.Close();
		file.Close();
	}else{
		//port, err := net.ResolveUDPAddr("udp4",local);
		port, err := net.ResolveUDPAddr("udp",local);
		if err != nil {
			fmt.Printf("Address error: %s (%s)\n",local,err)
			return
		}
		fmt.Printf("Listen UDP at %s...\n",local);
		//uconn, err := net.ListenUDP("udp4", port)
		uconn, err := net.ListenUDP("udp", port)
		if err != nil {
			fmt.Printf("Listen error: %s (%s)\n",local,err)
			return
		}
		file, _ := uconn.File()
		fd := file.Fd()
		ar := uconn.RemoteAddr()
		remote := ""
		if ar != nil { remote = ar.String() }
		if remote == "" { remote = "?" }

		// not yet received
		//fmt.Printf("Accepted at %s [%d] <- %s\n",local,fd,"")

		savfd := gshPA.Files[0]
		gshPA.Files[0] = fd;
		savenv := gshPA.Env
		gshPA.Env = append(savenv, "REMOTE_HOST="+remote)
		gshellv(gshCtx, argv[2:])
		gshPA.Env = savenv
		gshPA.Files[0] = savfd

		uconn.Close();
		file.Close();
	}
}

// empty line command
func xPwd(gshCtx GshContext, argv[]string){
	// execute context command, pwd + date
	// context notation, representation scheme, to be resumed at re-login
	cwd, _ := os.Getwd()
	switch {
	case isin("-a",argv):
		xChdirHistory(gshCtx,argv)
	case isin("-ls",argv):
		showFileInfo(cwd,argv)
	default:
		fmt.Printf("%s\n",cwd)
	case isin("-v",argv): // obsolete emtpy command
		t := time.Now()
		date := t.Format(time.UnixDate)
		exe, _ := os.Executable()
		host, _ := os.Hostname()
		fmt.Printf("{PWD=\"%s\"",cwd)
		fmt.Printf(" HOST=\"%s\"",host)
		fmt.Printf(" DATE=\"%s\"",date)
		fmt.Printf(" TIME=\"%s\"",t.String())
		fmt.Printf(" PID=\"%d\"",os.Getpid())
		fmt.Printf(" EXE=\"%s\"",exe)
		fmt.Printf("}\n")
	}
}

// History
// these should be browsed and edited by HTTP browser
// show the time of command with -t and direcotry with -ls
// openfile-history, sort by -a -m -c
// sort by elapsed time by -t -s
// search by "more" like interface
// edit history
// sort history, and wc or uniq
// CPU and other resource consumptions
// limit showing range (by time or so)
// export / import history
func xHistory(gshCtx GshContext, argv []string) (rgshCtx GshContext) {
	for i, v := range gshCtx.CommandHistory {
		// exclude commands not to be listed by default
		// internal commands may be suppressed by default
		if v.CmdLine == "" && !isin("-a",argv) {
			continue;
		}
		if !isin("-n",argv){ // like "fc"
			fmt.Printf("!%-3d ",i)
		}
		if isin("-v",argv){
			fmt.Println(v) // should be with it date
		}else{
			if isin("-l",argv) || isin("-l0",argv) {
				elps := v.EndAt.Sub(v.StartAt);
				start := v.StartAt.Format(time.Stamp)
				fmt.Printf("%s %11v/t ",start,elps)
			}
			if isin("-l",argv) && !isin("-l0",argv){
				fmt.Printf("%v",Rusagef("%t %u %s",argv,v.Rusagev))
			}
			if isin("-ls",argv){
				fmt.Printf("@%s ",v.WorkDir)
				// show the FileInfo of the output command??
			}
			fmt.Printf("%s",v.CmdLine)
			fmt.Printf("\n")
		}
	}
	return gshCtx
}
// !n - history index
func searchHistory(gshCtx GshContext, gline string) (string, bool, bool){
	if gline[0] == '!' {
		hix, err := strconv.Atoi(gline[1:])
		if err != nil {
			fmt.Printf("--E-- (%s : range)\n",hix)
			return "", false, true
		}
		if hix < 0 || len(gshCtx.CommandHistory) <= hix {
			fmt.Printf("--E-- (%d : out of range)\n",hix)
			return "", false, true
		}
		return gshCtx.CommandHistory[hix].CmdLine, false, false
	}
	// search
	//for i, v := range gshCtx.CommandHistory {
	//}
	return gline, false, false
}

// temporary adding to PATH environment
// cd name -lib for LD_LIBRARY_PATH
// chdir with directory history (date + full-path)
// -s for sort option (by visit date or so)
func xChdirHistory(gshCtx GshContext, argv []string){
	for i, v := range gshCtx.ChdirHistory {
		fmt.Printf("!%d ",i)
		fmt.Printf("%v ",v.MovedAt.Format(time.Stamp))
		showFileInfo(v.Dir,argv)
	}
}
func xChdir(gshCtx GshContext, argv []string) (rgshCtx GshContext) {
	cdhist := gshCtx.ChdirHistory
	if isin("?",argv ) || isin("-t",argv) {
		xChdirHistory(gshCtx,argv)
		return gshCtx
	}
	pwd, _ := os.Getwd()
	dir := ""
	if len(argv) <= 1 {
		dir = toFullpath("~")
	}else{
		dir = argv[1]
	}
	if strBegins(dir,"!") {
		if dir == "!0" {
			dir = gshCtx.StartDir
		}else
		if dir == "!!" {
			index := len(cdhist) - 1
			if 0 < index { index -= 1 }
			dir = cdhist[index].Dir
		}else{
			index, err := strconv.Atoi(dir[1:])
			if err != nil {
				fmt.Printf("--E-- xChdir(%v)\n",err)
				dir = "?"
			}else
			if len(gshCtx.ChdirHistory) <= index {
				fmt.Printf("--E-- xChdir(history range error)\n")
				dir = "?"
			}else{
				dir = cdhist[index].Dir
			}
		}
	}
	if dir != "?" {
		err := os.Chdir(dir)
		if err != nil {
			fmt.Printf("--E-- xChdir(%s)(%v)\n",argv[1],err)
		}else{
			cwd, _ := os.Getwd()
			if cwd != pwd {
				hist1 := GChdirHistory { }
				hist1.Dir = cwd
				hist1.MovedAt = time.Now()
				gshCtx.ChdirHistory = append(cdhist,hist1)
			}
		}
	}
	if isin("-ls",argv){
		cwd, _ := os.Getwd()
		showFileInfo(cwd,argv);
	}
	return gshCtx
}
func TimeValSub(tv1 *syscall.Timeval, tv2 *syscall.Timeval){
	*tv1 = syscall.NsecToTimeval(tv1.Nano() - tv2.Nano())  
}
func RusageSubv(ru1, ru2 [2]syscall.Rusage)([2]syscall.Rusage){
	TimeValSub(&ru1[0].Utime,&ru2[0].Utime)
	TimeValSub(&ru1[0].Stime,&ru2[0].Stime)
	TimeValSub(&ru1[1].Utime,&ru2[1].Utime)
	TimeValSub(&ru1[1].Stime,&ru2[1].Stime)
	return ru1
}
func TimeValAdd(tv1 syscall.Timeval, tv2 syscall.Timeval)(syscall.Timeval){
	tvs := syscall.NsecToTimeval(tv1.Nano() + tv2.Nano())  
	return tvs
}
/*
func RusageAddv(ru1, ru2 [2]syscall.Rusage)([2]syscall.Rusage){
	TimeValAdd(ru1[0].Utime,ru2[0].Utime)
	TimeValAdd(ru1[0].Stime,ru2[0].Stime)
	TimeValAdd(ru1[1].Utime,ru2[1].Utime)
	TimeValAdd(ru1[1].Stime,ru2[1].Stime)
	return ru1
}
*/

// Resource Usage
func Rusagef(fmtspec string, argv []string, ru [2]syscall.Rusage)(string){
	ut := TimeValAdd(ru[0].Utime,ru[1].Utime)
	st := TimeValAdd(ru[0].Stime,ru[1].Stime)
	fmt.Printf("%d.%06ds/u ",ut.Sec,ut.Usec) //ru[1].Utime.Sec,ru[1].Utime.Usec)
	fmt.Printf("%d.%06ds/s ",st.Sec,st.Usec) //ru[1].Stime.Sec,ru[1].Stime.Usec)
	return ""
}
func Getrusagev()([2]syscall.Rusage){
	var ruv = [2]syscall.Rusage{}
	syscall.Getrusage(syscall.RUSAGE_SELF,&ruv[0])
	syscall.Getrusage(syscall.RUSAGE_CHILDREN,&ruv[1])
	return ruv
}
func showRusage(what string,argv []string, ru *syscall.Rusage){
	fmt.Printf("%s: ",what);
	fmt.Printf("Usr=%d.%06ds",ru.Utime.Sec,ru.Utime.Usec)
	fmt.Printf(" Sys=%d.%06ds",ru.Stime.Sec,ru.Stime.Usec)
	fmt.Printf(" Rss=%vB",ru.Maxrss)
	if isin("-l",argv) {
		fmt.Printf(" MinFlt=%v",ru.Minflt)
		fmt.Printf(" MajFlt=%v",ru.Majflt)
		fmt.Printf(" IxRSS=%vB",ru.Ixrss)
		fmt.Printf(" IdRSS=%vB",ru.Idrss)
		fmt.Printf(" Nswap=%vB",ru.Nswap)
	fmt.Printf(" Read=%v",ru.Inblock)
	fmt.Printf(" Write=%v",ru.Oublock)
	}
	fmt.Printf(" Snd=%v",ru.Msgsnd)
	fmt.Printf(" Rcv=%v",ru.Msgrcv)
	//if isin("-l",argv) {
		fmt.Printf(" Sig=%v",ru.Nsignals)
	//}
	fmt.Printf("\n");
}
func xTime(gshCtx GshContext, argv[]string)(GshContext,bool){
	if 2 <= len(argv){
		gshCtx.LastRusage = syscall.Rusage{}
		rusagev1 := Getrusagev()
		xgshCtx, fin := gshellv(gshCtx,argv[1:])
		rusagev2 := Getrusagev()
		gshCtx = xgshCtx
		showRusage(argv[1],argv,&gshCtx.LastRusage)
		rusagev := RusageSubv(rusagev2,rusagev1)
		showRusage("self",argv,&rusagev[0])
		showRusage("chld",argv,&rusagev[1])
		return gshCtx, fin
	}else{
		rusage:= syscall.Rusage {}
		syscall.Getrusage(syscall.RUSAGE_SELF,&rusage)
		showRusage("self",argv, &rusage)
		syscall.Getrusage(syscall.RUSAGE_CHILDREN,&rusage)
		showRusage("chld",argv, &rusage)
		return gshCtx, false
	}
}
func xJobs(gshCtx GshContext, argv[]string){
	fmt.Printf("%d Jobs\n",len(gshCtx.BackGroundJobs))
	for ji, pid := range gshCtx.BackGroundJobs {
		//wstat := syscall.WaitStatus {0}
		rusage := syscall.Rusage {}
		//wpid, err := syscall.Wait4(pid,&wstat,syscall.WNOHANG,&rusage);
		wpid, err := syscall.Wait4(pid,nil,syscall.WNOHANG,&rusage);
		if err != nil {
			fmt.Printf("--E-- %%%d [%d] (%v)\n",ji,pid,err)
		}else{
			fmt.Printf("%%%d[%d](%d)\n",ji,pid,wpid)
			showRusage("chld",argv,&rusage)
		}
	}
}
func inBackground(gshCtx GshContext, argv[]string)(GshContext,bool){
	if gshCtx.CmdTrace { fmt.Printf("--I-- inBackground(%v)\n",argv) }
	gshCtx.BackGround = true // set background option
	xfin := false
	gshCtx, xfin = gshellv(gshCtx,argv)
	gshCtx.BackGround = false
	return gshCtx,xfin
}
// -o file without command means just opening it and refer by #N
// should be listed by "files" comnmand
func xOpen(gshCtx GshContext, argv[]string)(GshContext){
	var pv = []int{-1,-1}
	err := syscall.Pipe(pv)
	fmt.Printf("--I-- pipe()=[#%d,#%d](%v)\n",pv[0],pv[1],err)
	return gshCtx
}
func fromPipe(gshCtx GshContext, argv[]string)(GshContext){
	return gshCtx
}
func xClose(gshCtx GshContext, argv[]string)(GshContext){
	return gshCtx
}

// redirect
func redirect(gshCtx GshContext, argv[]string)(GshContext,bool){
	if len(argv) < 2 {
		return gshCtx, false
	}

	cmd := argv[0]
	fname := argv[1]
	var file *os.File = nil

	fdix := 0
	mode := os.O_RDONLY

	switch {
	case cmd == "-i" || cmd == "<":
		fdix = 0
		mode = os.O_RDONLY
	case cmd == "-o" || cmd == ">":
		fdix = 1
		mode = os.O_RDWR | os.O_CREATE
	case cmd == "-a" || cmd == ">>":
		fdix = 1
		mode = os.O_RDWR | os.O_CREATE | os.O_APPEND
	}
	if fname[0] == '#' {
		fd, err := strconv.Atoi(fname[1:])
		if err != nil {
			fmt.Printf("--E-- (%v)\n",err)
			return gshCtx, false
		}
		file = os.NewFile(uintptr(fd),"MaybePipe")
	}else{
		xfile, err := os.OpenFile(argv[1], mode, 0600)
		if err != nil {
			fmt.Printf("--E-- (%s)\n",err)
			return gshCtx, false
		}
		file = xfile
	}
	gshPA := gshCtx.gshPA
	savfd := gshPA.Files[fdix]
	gshPA.Files[fdix] = file.Fd()
	fmt.Printf("--I-- Opened [%d] %s\n",file.Fd(),argv[1])
	gshCtx, _ = gshellv(gshCtx, argv[2:])
	gshPA.Files[fdix] = savfd

	return gshCtx, false
}

//fmt.Fprintf(res, "GShell Status: %q", html.EscapeString(req.URL.Path))
func httpHandler(res http.ResponseWriter, req *http.Request){
	path := req.URL.Path
	fmt.Printf("--I-- Got HTTP Request(%s)\n",path)
	{
		gshCtx, _ :=  setupGshContext()
		fmt.Printf("--I-- %s\n",path[1:])
		gshCtx, _ = tgshelll(gshCtx,path[1:])
	}
	fmt.Fprintf(res, "Hello(^-^)/\n%s\n",path)
}
func httpServer(gshCtx GshContext, argv []string){
	http.HandleFunc("/", httpHandler)
	accport := "localhost:9999"
	fmt.Printf("--I-- HTTP Server Start at [%s]\n",accport)
	http.ListenAndServe(accport,nil)
}
func xGo(gshCtx GshContext, argv[]string){
	go gshellv(gshCtx,argv[1:]);
}
func xPs(gshCtx GshContext, argv[]string)(GshContext){
	return gshCtx
}

// Plugin
// plugin [-ls [names]] to list plugins
// Reference: plugin source code
func whichPlugin(gshCtx GshContext,name string,argv[]string)(pi *PluginInfo){
	pi = nil	
	for _,p := range gshCtx.PluginFuncs {
		if p.Name == name && pi == nil {
			pi = &p
		}
		if !isin("-s",argv){
			//fmt.Printf("%v %v ",i,p)
			if isin("-ls",argv){
				showFileInfo(p.Path,argv)
			}else{
				fmt.Printf("%s\n",p.Name)
			}
		}
	}
	return pi
}
func xPlugin(gshCtx GshContext, argv[]string)(GshContext,error){
	if len(argv) == 0 || argv[0] == "-ls" {
		whichPlugin(gshCtx,"",argv)
		return gshCtx, nil
	}
	name := argv[0]
	Pin := whichPlugin(gshCtx,name,[]string{"-s"})
	if Pin != nil {
		os.Args = argv // should be recovered?
		Pin.Addr.(func())()
		return gshCtx,nil
	}
	sofile := toFullpath(argv[0] + ".so") // or find it by which($PATH)

	p, err := plugin.Open(sofile)
	if err != nil {
		fmt.Printf("--E-- plugin.Open(%s)(%v)\n",sofile,err)
		return gshCtx, err
	}
	fname := "Main"
	f, err := p.Lookup(fname)
	if( err != nil ){
		fmt.Printf("--E-- plugin.Lookup(%s)(%v)\n",fname,err)
		return gshCtx, err
	}
	pin := PluginInfo {p,f,name,sofile} 
	gshCtx.PluginFuncs = append(gshCtx.PluginFuncs,pin)
	fmt.Printf("--I-- added (%d)\n",len(gshCtx.PluginFuncs))

	//fmt.Printf("--I-- first call(%s:%s)%v\n",sofile,fname,argv)
	os.Args = argv
	f.(func())()
	return gshCtx, err
}
func Args(gshCtx *GshContext, argv[]string){
	for i,v := range os.Args {
		fmt.Printf("[%v] %v\n",i,v)
	}
}
func Version(gshCtx *GshContext, argv[]string){
	if isin("-l",argv) {
		fmt.Printf("%v/%v (%v)",NAME,VERSION,DATE);
	}else{
		fmt.Printf("%v",VERSION);
	}
	if !isin("-n",argv) {
		fmt.Printf("\n")
	}
}

// Command Interpreter
func gshellv(gshCtx GshContext, argv []string) (_ GshContext, fin bool) {
	fin = false

	if gshCtx.CmdTrace { fmt.Fprintf(os.Stderr,"--I-- gshellv((%d))\n",len(argv)) }
	if len(argv) <= 0 {
		return gshCtx, false
	}
	xargv := []string{}
	for ai := 0; ai < len(argv); ai++ {
		xargv = append(xargv,strsubst(&gshCtx,argv[ai],false))
	}
	argv = xargv
	if false {
		for ai := 0; ai < len(argv); ai++ {
			fmt.Printf("[%d] %s [%d]%T\n",
				ai,argv[ai],len(argv[ai]),argv[ai])
		}
	}
	cmd := argv[0]
	if gshCtx.CmdTrace { fmt.Fprintf(os.Stderr,"--I-- gshellv(%d)%v\n",len(argv),argv) }
	switch { // https://tour.golang.org/flowcontrol/11
	case cmd == "":
		xPwd(gshCtx,[]string{}); // emtpy command
	case cmd == "-x":
		gshCtx.CmdTrace = ! gshCtx.CmdTrace
	case cmd == "-ot":
		sconnect(gshCtx, true, argv)
	case cmd == "-ou":
		sconnect(gshCtx, false, argv)
	case cmd == "-it":
		saccept(gshCtx, true , argv)
	case cmd == "-iu":
		saccept(gshCtx, false, argv)
	case cmd == "-i" || cmd == "<" || cmd == "-o" || cmd == ">" || cmd == "-a" || cmd == ">>" || cmd == "-s" || cmd == "><":
		redirect(gshCtx, argv)
	case cmd == "|":
		gshCtx = fromPipe(gshCtx, argv)
	case cmd == "args":
		Args(&gshCtx,argv)
	case cmd == "bg" || cmd == "-bg":
		rgshCtx, rfin := inBackground(gshCtx,argv[1:])
		return rgshCtx, rfin
	case cmd == "call":
		gshCtx, _ = excommand(gshCtx, false,argv[1:])
	case cmd == "cd" || cmd == "chdir":
		gshCtx = xChdir(gshCtx,argv);
	case cmd == "close":
		gshCtx = xClose(gshCtx,argv)
	case cmd == "dec" || cmd == "decode":
		Dec(&gshCtx,argv)
	case cmd == "#define":
	case cmd == "echo":
		echo(argv,true)
	case cmd == "enc" || cmd == "encode":
		Enc(&gshCtx,argv)
	case cmd == "env":
		env(argv)
	case cmd == "eval":
		xEval(argv[1:],true)
	case cmd == "exec":
		gshCtx, _ = excommand(gshCtx, true,argv[1:])
		// should not return here
	case cmd == "exit" || cmd == "quit":
		// write Result code EXIT to 3>
		return gshCtx, true
	case cmd == "-find" || cmd == "fin" || cmd == "ufind" || cmd == "uf" || cmd == "fu":
		gshCtx = xFind(gshCtx,argv[1:])
	case cmd == "fork":
		// mainly for a server
	case cmd == "-gen":
		gen(gshCtx, argv)
	case cmd == "-go":
		xGo(gshCtx, argv)
	case cmd == "-grep":
		gshCtx = xFind(gshCtx,argv)
	case cmd == "history" || cmd == "hi": // hi should be alias
		gshCtx = xHistory(gshCtx, argv)
	case cmd == "jobs":
		xJobs(gshCtx,argv)
	case cmd == "-ls":
		gshCtx = xFind(gshCtx,argv)
	case cmd == "nop":
	case cmd == "pipe":
		gshCtx = xOpen(gshCtx,argv)
	case cmd == "plug" || cmd == "plugin" || cmd == "pin":
		gshCtx,_ = xPlugin(gshCtx,argv[1:])
	case cmd == "ps":
		xPs(gshCtx,argv)
	case cmd == "pstitle": // to be gsh.title
	case cmd == "repeat" || cmd == "rep": // repeat cond command
		repeat(gshCtx,argv)
	case cmd == "set":
		// set name ...
	case cmd == "serv":
		httpServer(gshCtx,argv)
	case cmd == "sleep":
		sleep(gshCtx,argv)
	case cmd == "lnsp":
		SplitLine(&gshCtx,argv)
	case cmd == "time":
		gshCtx, fin = xTime(gshCtx,argv)
	case cmd == "pwd":
		xPwd(gshCtx,argv);
	case cmd == "ver" || cmd == "-ver" || cmd == "version":
		Version(&gshCtx,argv)
	case cmd == "where":
		// data file or so?
	case cmd == "which":
		which("PATH",argv);
	default:
		if whichPlugin(gshCtx,cmd,[]string{"-s"}) != nil {
			gshCtx, _ = xPlugin(gshCtx,argv)
		}else{
			gshCtx, _ = excommand(gshCtx,false,argv)
		}
	}
	return gshCtx, fin
}

func gshelll(gshCtx GshContext, gline string) (gx GshContext, rfin bool) {
	argv := strings.Split(string(gline)," ")
	gshCtx, fin := gshellv(gshCtx,argv)
	return gshCtx, fin
}
func tgshelll(gshCtx GshContext, gline string) (gx GshContext, xfin bool) {
	start := time.Now()
	gshCtx, fin := gshelll(gshCtx,gline)
	end := time.Now()
	elps := end.Sub(start);
	fmt.Printf("--I-- " + time.Now().Format(time.Stamp) + "(%d.%09ds)\n",
		elps/1000000000,elps%1000000000)
	return gshCtx, fin
}
func Ttyid() (int) {
	fi, err := os.Stdin.Stat()
	if err != nil {
		return 0;
	}
	//fmt.Printf("Stdin: %v Dev=%d\n",
	//	fi.Mode(),fi.Mode()&os.ModeDevice)
	if (fi.Mode() & os.ModeDevice) != 0 {
		stat := syscall.Stat_t{};
		err := syscall.Fstat(0,&stat)
		if err != nil {
			//fmt.Printf("--I-- Stdin: (%v)\n",err)
		}else{
			//fmt.Printf("--I-- Stdin: rdev=%d %d\n",
			//	stat.Rdev&0xFF,stat.Rdev);
			//fmt.Printf("--I-- Stdin: tty%d\n",stat.Rdev&0xFF);
			return int(stat.Rdev & 0xFF)
		}
	}
	return 0
}
func ttyfile(gshCtx GshContext) string {
	//fmt.Printf("--I-- GSH_HOME=%s\n",gshCtx.GshHomeDir)
	ttyfile := gshCtx.GshHomeDir + "/" + "gsh-tty" +
		 fmt.Sprintf("%02d",gshCtx.TerminalId)
		 //strconv.Itoa(gshCtx.TerminalId)
	//fmt.Printf("--I-- ttyfile=%s\n",ttyfile)
	return ttyfile
}
func ttyline(gshCtx GshContext) (*os.File){
	file, err := os.OpenFile(ttyfile(gshCtx),
		os.O_RDWR|os.O_CREATE|os.O_TRUNC,0600)
	if err != nil {
		fmt.Printf("--F-- cannot open %s (%s)\n",ttyfile(gshCtx),err)
		return file;
	}
	return file
}
// Command Line Editor
func getline(gshCtx GshContext, hix int, skipping, with_exgetline bool, gsh_getlinev[]string, prevline string) (string) {
	if( skipping ){
		reader := bufio.NewReaderSize(os.Stdin,LINESIZE)
		line, _, _ := reader.ReadLine()
		return string(line)
	}else
	if( with_exgetline && gshCtx.GetLine != "" ){
		//var xhix int64 = int64(hix); // cast
		newenv := os.Environ()
		newenv = append(newenv, "GSH_LINENO="+strconv.FormatInt(int64(hix),10) )

		tty := ttyline(gshCtx)
		tty.WriteString(prevline)
		Pa := os.ProcAttr {
			"", // start dir
			newenv, //os.Environ(),
			[]*os.File{os.Stdin,os.Stdout,os.Stderr,tty},
			nil,
		}
//fmt.Printf("--I-- getline=%s // %s\n",gsh_getlinev[0],gshCtx.GetLine)
proc, err := os.StartProcess(gsh_getlinev[0],[]string{"getline","getline"},&Pa)
		if err != nil {
			fmt.Printf("--F-- getline process error (%v)\n",err)
			// for ; ; { }
			return "exit (getline program failed)"
		}
		//stat, err := proc.Wait()
		proc.Wait()
		buff := make([]byte,LINESIZE)
		count, err := tty.Read(buff)
		//_, err = tty.Read(buff)
		//fmt.Printf("--D-- getline (%d)\n",count)
		if err != nil {
			if ! (count == 0) { // && err.String() == "EOF" ) {
				fmt.Printf("--E-- getline error (%s)\n",err)
			}
		}else{
			//fmt.Printf("--I-- getline OK \"%s\"\n",buff)
		}
		tty.Close()
		return string(buff[0:count])
	}else{
		// if isatty {
			fmt.Printf("!%d",hix)
			fmt.Print(PROMPT)
		// }
		reader := bufio.NewReaderSize(os.Stdin,LINESIZE)
		line, _, _ := reader.ReadLine()
		return string(line)
	}
}
//
// $USERHOME/.gsh/
//		gsh-rc.txt, or gsh-configure.txt
//              gsh-history.txt
//              gsh-aliases.txt // should be conditional?
//
func gshSetupHomedir(gshCtx GshContext) (GshContext, bool) {
	homedir,found := userHomeDir()
	if !found {
		fmt.Printf("--E-- You have no UserHomeDir\n")
		return gshCtx, true
	}
	gshhome := homedir + "/" + GSH_HOME
	_, err2 := os.Stat(gshhome)
	if err2 != nil {
		err3 := os.Mkdir(gshhome,0700)
		if err3 != nil {
			fmt.Printf("--E-- Could not Create %s (%s)\n",
				gshhome,err3)
			return gshCtx, true
		}
		fmt.Printf("--I-- Created %s\n",gshhome)
	}
	gshCtx.GshHomeDir = gshhome
	return gshCtx, false
}
func setupGshContext()(GshContext,bool){
	gshPA := syscall.ProcAttr {
		"", // the staring directory
		os.Environ(), // environ[]
		[]uintptr{os.Stdin.Fd(),os.Stdout.Fd(),os.Stderr.Fd()},
		nil, // OS specific
	}
	cwd, _ := os.Getwd()
	gshCtx := GshContext {
		cwd, // StartDir
		"", // GetLine
		[]GChdirHistory { {cwd,time.Now()} }, // ChdirHistory
		gshPA,
		[]GCommandHistory{}, //something for invokation?
		GCommandHistory{}, // CmdCurrent
		false,
		[]int{},
		syscall.Rusage{},
		"", // GshHomeDir
		Ttyid(),
		false,
		[]PluginInfo{},
	}
	err := false
	gshCtx, err = gshSetupHomedir(gshCtx)
	return gshCtx, err
}
// Main loop
func script(gshCtxGiven *GshContext) (_ GshContext) {
	gshCtx,err0 := setupGshContext()
	if err0 {
		return gshCtx;
	}
	//fmt.Printf("--I-- GSH_HOME=%s\n",gshCtx.GshHomeDir)
	//resmap()
	gsh_getlinev, with_exgetline :=
		 which("PATH",[]string{"which","gsh-getline","-s"})
	if with_exgetline {
		gsh_getlinev[0] = toFullpath(gsh_getlinev[0])
		gshCtx.GetLine = toFullpath(gsh_getlinev[0])
	}else{
	fmt.Printf("--W-- No gsh-getline found. Using internal getline.\n");
	}

	ghist0 := gshCtx.CmdCurrent // something special, or gshrc script, or permanent history
	gshCtx.CommandHistory = append(gshCtx.CommandHistory,ghist0)

	prevline := ""
	skipping := false
	for hix := len(gshCtx.CommandHistory); ; {
		gline := getline(gshCtx,hix,skipping,with_exgetline,gsh_getlinev,prevline)
		if skipping {
			if strings.Index(gline,"fi") == 0 {
				fmt.Printf("fi\n");
				skipping = false;
			}else{
				//fmt.Printf("%s\n",gline);
			}
			continue
		}
		if strings.Index(gline,"if") == 0 {
			//fmt.Printf("--D-- if start: %s\n",gline);
			skipping = true;
			continue
		}
		gline = strsubst(&gshCtx,gline,true)
		/*
		// should be cared in substitution ?
		if 0 < len(gline) && gline[0] == '!' {
			xgline, set, err := searchHistory(gshCtx,gline)
			if err {
				continue
			}
			if set {
				// set the line in command line editor
			}
			gline = xgline
		}
		*/
		ghist := gshCtx.CmdCurrent
		ghist.WorkDir,_ = os.Getwd()
		ghist.StartAt = time.Now()
		rusagev1 := Getrusagev()
		gshCtx.CmdCurrent.FoundFile = []string{}
		xgshCtx, fin := tgshelll(gshCtx,gline)
		rusagev2 := Getrusagev()
		ghist.Rusagev = RusageSubv(rusagev2,rusagev1)
		gshCtx = xgshCtx
		ghist.EndAt = time.Now()
		ghist.CmdLine = gline
		ghist.FoundFile = gshCtx.CmdCurrent.FoundFile

		/* record it but not show in list by default
		if len(gline) == 0 {
			continue
		}
		if gline == "hi" || gline == "history" { // don't record it
			continue
		}
		*/
		gshCtx.CommandHistory = append(gshCtx.CommandHistory, ghist)
		if fin {
			break;
		}
		prevline = gline;
		hix++;
	}
	return gshCtx
}
func main() {
	argv := os.Args
	if 1 < len(argv) {
		if isin("version",argv){
			Version(nil,argv)
			return
		}
		comx := isinX("-c",argv)
		if 0 < comx {
			gshCtx,err := setupGshContext()
			if !err {
				gshellv(gshCtx,argv[comx+1:])
			}
			return
		}
	}
	script(nil)
	//gshCtx := script(nil)
	//gshelll(gshCtx,"time")
}
//
//
Consideration
// - inter gsh communication, possibly running in remote hosts -- to be remote shell
// - merged histories of multiple parallel gsh sessions
// - alias as a function
// - instant alias end environ export to the permanent > ~/.gsh/gsh-alias and gsh-environ
// - retrieval PATH of files by its type
// - gsh as an IME
// - gsh a scheduler in precise time of within a millisecond
// - all commands have its subucomand after "---" symbol
// - filename expansion by "-find" command
// - history of ext code and output of each commoand
// - "script" output for each command by pty-tee or telnet-tee
// - $BUILTIN command in PATH to show the priority
// - "?" symbol in the command (not as in arguments) shows help request 
// - searching command with wild card like: which ssh-*
// - longformat prompt after long idle time (should dismiss by BS)
// - customizing by building plugin and dynamically linking it
// - generating syntactic element like "if" by macro expansion (like CPP) >> alias
// - "!" symbol should be used for negation, don't wast it just for job control
// - don't put too long output to tty, record it into GSH_HOME/session-id/comand-id.log
// - making canonical form of command at the start adding quatation or white spaces
// - name(a,b,c) ... use "(" and ")" to show both delimiter and realm
// - name? or name! might be useful
// - htar format - packing directory contents into a single html file using data scheme
//---END--- (^-^)/ITS more
/*
References

The Go Programming Language MDN web docs HTML CSS: Selectors repeat HTTP JavaScript: ...

--> */ //

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