Last change: 2014-12-30

While browsing, I found this except from the book Unix Power Tools:

... 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)

I immediately asked myself: what could Bournegol look like? Well, it's not that easy to find the original Bourne Shell sourcecode, so, after some googling, I thought I might put an example of Bournegol on my homepage, so other people have the chance to find about "Bournegol" without the tedious search.

(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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