/* * Definitions used in the interpreter */extern void Xappend(void), Xasync(void), Xbackq(void), Xbang(void), Xclose(void);extern void Xconc(void), Xcount(void), Xdelfn(void), Xdol(void), Xqw(void), Xdup(void);extern void Xexit(void), Xfalse(void), Xfn(void), Xfor(void), Xglob(void);extern void Xjump(void), Xmark(void), Xmatch(void), Xpipe(void), Xread(void), Xhere(void), Xhereq(void);extern void Xrdwr(void), Xsrcline(void);extern void Xunredir(void), Xstar(void), Xreturn(void), Xsubshell(void);extern void Xtrue(void), Xword(void), Xwrite(void), Xpipefd(void), Xcase(void);extern void Xlocal(void), Xunlocal(void), Xassign(void), Xsimple(void), Xpopm(void), Xpush(void);extern void Xrdcmds(void), Xwastrue(void), Xif(void), Xifnot(void), Xpipewait(void);extern void Xpopredir(void), Xsub(void), Xeflag(void), Xsettrue(void);extern void Xerror1(char*);extern void Xerror2(char*,char*);extern void Xerror3(char*,char*,char*); /* * word lists are in correct order, * i.e. word0->word1->word2->word3->0 */struct word{	char *word;	word *next;};struct list{	word *words;	list *next;};word *newword(char *, word *), *copywords(word *, word *); struct redir{	int type;			/* what to do */	int from, to;			/* what to do it to */	redir *next;			/* what else to do (reverse order) */}; /* * redir types */#define	ROPEN	1			/* dup2(from, to); close(from); */#define	RDUP	2			/* dup2(from, to); */#define	RCLOSE	3			/* close(from); */void	shuffleredir(void); struct thread{	code *code;			/* code for this thread */	int pc;				/* code[pc] is the next instruction */	int line;			/* source code line for Xsrcline */	list *argv;			/* argument stack */	redir *redir;			/* redirection stack */	redir *startredir;		/* redir inheritance point */	var *local;			/* list of local variables */	lexer *lex;			/* lexer for Xrdcmds */	int iflag;			/* interactive? */	int pid;			/* process for Xpipewait to wait for */	char *status;			/* status for Xpipewait */	thread *ret;			/* who continues when this finishes */};extern thread *runq;void turfstack(var*); extern int mypid;extern int ntrap;			/* number of outstanding traps */extern int trap[NSIG];			/* number of outstanding traps per type */ code *codecopy(code*);extern code *codebuf;			/* compiler output */extern int ifnot; struct builtin{	char *name;	void (*fnc)(void);};extern void (*builtinfunc(char *name))(void); void execcd(void), execwhatis(void), execeval(void), execexec(void);int execforkexec(void);void execexit(void), execshift(void);void execwait(void), execumask(void), execdot(void), execflag(void);void execfunc(var*), execcmds(io*, char*, var*, redir*);void startfunc(var*, word*, var*, redir*); char *srcfile(thread*);char *getstatus(void);