日: 2020年8月18日

To be written

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
		scanf		// string decomposer
		interpreter	// command interpreter
		main

// 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 = "0.1.4"
var DATE = "2020-0818a"
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
// --T-- time and resouce usage
// --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 // should be [map]
	CmdTime		bool // should be [map]
	PluginFuncs	[]PluginInfo
	iValues		[]string
	iDelimiter	string // field sepearater of print out
	iFormat		string // default print format (of integer)
}

func strBegins(str, pat string)(bool){
	if len(pat) <= 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")
	}
}

// Scanf // string decomposer
// scanf [format] [input]
func scanv(sstr string)(strv[]string){
	strv = strings.Split(sstr," ")
	return strv
}
func scanUntil(src,end string)(rstr string,leng int){
	idx := strings.Index(src,end)
	if 0 <= idx {
		rstr = src[0:idx]
		return rstr,idx+len(end)
	}
	return src,0
}
func (gsh*GshContext)printVal(fmts string, vstr string){
	//vint,err := strconv.Atoi(vstr)
	var ival int64 = 0
	n := 0
	err := error(nil)
	if strBegins(vstr,"_") {
		vx,_ := strconv.Atoi(vstr[1:])
		if vx < len(gsh.iValues) {
			vstr = gsh.iValues[vx]
		}else{
		}
	}
	// should use Eval()
	if strBegins(vstr,"0x") {
		n,err = fmt.Sscanf(vstr[2:],"%x",&ival)
	}else{
		n,err = fmt.Sscanf(vstr,"%d",&ival)
//fmt.Printf("--D-- n=%d err=(%v) {%s}=%v\n",n,err,vstr, ival)
	}
	if n == 1 && err == nil {
		//fmt.Printf("--D-- formatn(%v) ival(%v)\n",fmts,ival)
		fmt.Printf("%"+fmts,ival)
	}else{
		fmt.Printf("%"+fmts,vstr)
	}
}
func (gsh*GshContext)printfv(fmts,div string,list[]string){
	//fmt.Printf("{%d}",len(list))
	//curfmt := "v"
	outlen := 0
	curfmt := gsh.iFormat
	if 0 < len(fmts) {
		for xi := 0; xi < len(fmts); xi++ {
			fch := fmts[xi]
			if fch == '%' {
				if xi+1 < len(fmts) {
					curfmt = string(fmts[xi+1])
gsh.iFormat = curfmt
					xi += 1
	if xi+1 < len(fmts) && fmts[xi+1] == '(' {
		vals,leng := scanUntil(fmts[xi+2:],")")
		//fmt.Printf("--D-- show fmt(%v) val(%v) next(%v)\n",curfmt,vals,leng)
		gsh.printVal(curfmt,vals)
		xi += 2+leng-1
		outlen += 1
	}
					continue
				}
			}
			if fch == '_' {
				hi,leng := scanInt(fmts[xi+1:])
				if 0 < leng {
					if hi < len(gsh.iValues) {
						gsh.printVal(curfmt,gsh.iValues[hi])
					}else{
						fmt.Printf("((out-range))")
					}
					xi += leng
					continue;
				}
			}
			fmt.Printf("%c",fch)
			outlen += 1
		}
	}else{
		//fmt.Printf("--D-- print {%s}\n")
		for i,v := range list {
			if 0 < i {
				fmt.Printf(div)
			}
			gsh.printVal(curfmt,v)
			outlen += 1
			/*
			if v[0] == '_' {
				vx,_ := strconv.Atoi(v[1:])
				if vx < len(gsh.iValues) {
					fmt.Printf("%v",gsh.iValues[vx])
				}
			}else{
				fmt.Printf("%v",v)
			}
			*/
		}
	}
	if 0 < outlen {
		fmt.Printf("\n")
	}
}
func (gsh*GshContext)Scanv(argv[]string){
	//fmt.Printf("--D-- Scanv(%v)\n",argv)
	if len(argv) == 1 {
		return
	}
	argv = argv[1:]
	fmts := ""
	if strBegins(argv[0],"-F") {
		fmts = argv[0]
		gsh.iDelimiter = fmts
		argv = argv[1:]
	}
	input := strings.Join(argv," ")
	if fmts == "" { // simple decomposition
		v := scanv(input)
		gsh.iValues = v
		//fmt.Printf("%v\n",strings.Join(v,","))
	}else{
		v := make([]string,8)
		n,err := fmt.Sscanf(input,fmts,&v[0],&v[1],&v[2],&v[3])
		fmt.Printf("--D-- Scanf ->(%v) n=%d err=(%v)\n",v,n,err)
		gsh.iValues = v
	}
}
func (gsh*GshContext)Printv(argv[]string){
	//fmt.Printf("--D-- Printv(%v)\n",argv)
	//fmt.Printf("%v\n",strings.Join(gsh.iValues,","))
	div := gsh.iDelimiter
	fmts := ""
	argv = argv[1:]
	if 0 < len(argv) {
		if strBegins(argv[0],"-F") {
			div = argv[0][2:]
			argv = argv[1:]
		}
	}
	if 0 < len(argv) {
		fmts = strings.Join(argv," ")
	}
	gsh.printfv(fmts,div,gsh.iValues)
}
func (gsh*GshContext)Sortv(argv[]string){
	sv := gsh.iValues
	sort.Slice(sv , func(i,j int) bool {
		return sv[i] < sv[j]
	})
}
func (gsh*GshContext)Shiftv(argv[]string){
	vi := len(gsh.iValues)
	if 0 < vi {
		if isin("-r",argv) {
			top := gsh.iValues[0]
			gsh.iValues = append(gsh.iValues[1:],top)
		}else{
			gsh.iValues = gsh.iValues[1:]
		}
	}
}

// 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 == "-xt":
		gshCtx.CmdTime = ! gshCtx.CmdTime
	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 == "fdls":
		// dump the attributes of fds (of other process)
	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 == "lnsp":
		SplitLine(&gshCtx,argv)
	case cmd == "-ls":
		gshCtx = xFind(gshCtx,argv)
	case cmd == "nop":
		// do nothing
	case cmd == "pipe":
		gshCtx = xOpen(gshCtx,argv)
	case cmd == "plug" || cmd == "plugin" || cmd == "pin":
		gshCtx,_ = xPlugin(gshCtx,argv[1:])
	case cmd == "print":
		// output internal slice // also sprintf should be
		gshCtx.Printv(argv)
	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 == "scan":
		// scan input (or so in fscanf) to internal slice (like Files or map)
		gshCtx.Scanv(argv)
	case cmd == "set":
		// set name ...
	case cmd == "serv":
		httpServer(gshCtx,argv)
	case cmd == "shift":
		gshCtx.Shiftv(argv)
	case cmd == "sleep":
		sleep(gshCtx,argv)
	case cmd == "sort":
		gshCtx.Sortv(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);
	if gshCtx.CmdTime {
		fmt.Printf("--T-- " + 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,
		false,
		[]PluginInfo{},
		[]string{},
		" ",
		"v",
	}
	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")
}
//

// - 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

The Go Programming Language


MDN web docs
 HTML
 CSS:
   Selectors
   repeat
 HTTP
 JavaScript:
 ...