Last change: 2014-12-30

Bournegol???

... To fix it, first get the source, and then change it in the obvious three places in xec.c. You will have to learn Bournegol [the ALGOL-like dialect of C that Steve Bourne used to write the original Bourne shell-JP ]. Another alternative is to replace /bin/sh with one of the free sh look-alikes... (CT in comp.unix.questions on Usenet, 20 February 1990)

(many years later I found this paper, A Partial Tour Through the UNIX Shell, which makes for very nice reading). Ok, without any further ado, here is an excerpt of the file xec.c, referenced above, supposedly from the 7th Edition UNIX, that gives you an impression of bournegol:

LOCAL INT	parent;

SYSTAB		commands;

/* ========	command execution	========*/

execute(argt, execflg, pf1, pf2)
	TREPTR		argt;
	INT		*pf1, *pf2;
{
	/* `stakbot' is preserved by this routine */
	REG TREPTR	t;
	STKPTR		sav=savstak();

	sigchk();

	IF (t=argt) ANDF execbrk==0
	THEN	REG INT		treeflgs;
		INT		oldexit, type;
		REG STRING	*com;

		treeflgs = t->tretyp; type = treeflgs&COMMSK;
		oldexit=exitval; exitval=0;

		SWITCH type IN

		case TCOM:
			BEGIN
			STRING		a1;
			INT		argn, internal;
			ARGPTR		schain=gchain;
			IOPTR		io=t->treio;
			gchain=0;
			argn = getarg(t);
			com=scan(argn);
			a1=com[1]; gchain=schain;

			IF (internal=syslook(com[0],commands)) ORF argn==0
			THEN	setlist(t->comset, 0);
			FI

			IF argn ANDF (flags&noexec)==0
			THEN	/* print command if execpr */
				IF flags&execpr
				THEN	argn=0;	prs(execpmsg);
					WHILE com[argn]!=ENDARGS
					DO prs(com[argn++]); blank() OD
					newline();
				FI

				SWITCH internal IN

				case SYSDOT:
					IF a1
					THEN	REG INT		f;
	
						IF (f=pathopen(getpath(a1), a1)) < 0
						THEN failed(a1,notfound);
						ELSE execexp(0,f);
						FI
					FI
					break;
	
				case SYSTIMES:
					{
					L_INT	t[4]; times(t);
					prt(t[2]); blank(); prt(t[3]); newline();
					}
					break;
	
				case SYSEXIT:
					exitsh(a1?stoi(a1):oldexit);
	

				case SYSTRAP:
					IF a1
					THEN	BOOL	clear;
						IF (clear=digit(*a1))==0
						THEN	++com;
						FI
						WHILE *++com
						DO INT	i;
						   IF (i=stoi(*com))>=MAXTRAP ORF i<MINTRAP
						   THEN	failed(*com,badtrap);
						   ELIF clear
						   THEN	clrsig(i);
						   ELSE	replace(&trapcom[i],a1);
							IF *a1
							THEN	getsig(i);
							ELSE	ignsig(i);
							FI
						   FI
						OD
					ELSE	/* print out current traps */
						INT		i;
	
						FOR i=0; i<MAXTRAP; i++
						DO IF trapcom[i]
						   THEN	prn(i); prs(colon); prs(trapcom[i]); newline();
						   FI
						OD
					FI
					break;
	

                                                   
		case TFORK:
			IF execflg ANDF (treeflgs&(FAMP|FPOU))==0
			THEN	parent=0;
			ELSE	WHILE (parent=fork()) == -1
				DO sigchk(); alarm(10); pause() OD
			FI

			IF parent
			THEN	/* This is the parent branch of fork;    */
				/* it may or may not wait for the child. */
				IF treeflgs&FPRS ANDF flags&ttyflg
				THEN	prn(parent); newline();
				FI
				IF treeflgs&FPCL THEN closepipe(pf1) FI
				IF (treeflgs&(FAMP|FPOU))==0
				THEN	await(parent);
				ELIF (treeflgs&FAMP)==0
				THEN	post(parent);
				ELSE	assnum(&pcsadr, parent);
				FI

				chktrap();
				break;

(Note the single use of curly braces after case SYSTIMES. This and the lowercase case let me believe this segment might have been added at a later stage). The necesssary macro definitions to understand (if you dare to try) the above excerpt can be found in the file mac.h:

/*
 *	UNIX shell
 *
 *	S. R. Bourne
 *	Bell Telephone Laboratories
 *
 */

#define LOCAL	static
#define PROC	extern
#define TYPE	typedef
#define STRUCT	TYPE struct
#define UNION	TYPE union
#define REG	register

#define IF	if(
#define THEN	){
#define ELSE	} else {
#define ELIF	} else if (
#define FI	;}

#define BEGIN	{
#define END	}
#define SWITCH	switch(
#define IN	){
#define ENDSW	}
#define FOR	for(
#define WHILE	while(
#define DO	){
#define OD	;}
#define REP	do_lbr
#define PER	}while(
#define DONE	);
#define LOOP	for(;;){
#define POOL	}


#define SKIP	;
#define DIV	/
#define REM	%
#define NEQ	^
#define ANDF	&&
#define ORF	||

#define TRUE	(-1)
#define FALSE	0
#define LOBYTE	0377
#define STRIP	0177
#define QUOTE	0200

#define EOF	0
#define NL	'\n'
#define SP	' '
#define LQ	'`'
#define RQ	'\''
#define MINUS	'-'
#define COLON	':'

#define MAX(a,b)	((a)>(b)?(a):(b))

Hope you found this interesting ;)

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