Modified Tom Duff's com. (Original http://www.iq0.com/duffgram/com.c)

com.c

/*% cc -O0 -g % -o #
 * com [-n] [file ...]
 * looks for the sequence /*% in each file, and sends the rest of the
 * line off to the shell, after replacing any instances of a `%' character
 * with the filename, and any instances of `#' with the filename with its
 * suffix removed.  Used to allow information about how to compile a program
 * to be stored with the program.  The -n flag causes com not to
 * act, but to print out the action it would have taken.
 *
 * This version of com would also create compile_flags.txt for clangd if
 * -n flag is not specified.
 */

/* Copyright © 2022,2024 Artsiom Karakin
 * Copyright © 2002-2011 Tom Duff
 *
 * See end of this file for LICENSE
 */


#include <sys/types.h>
#include <sys/wait.h>

#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <err.h>

#define TWOPAGES 8192
#define BYTE unsigned char


int nflag=0;
int maxstat=0;
char command[TWOPAGES];



void make(char []);

int
main(int argc, char *argv[]){
	int i;
	FILE *comfile;
	char str[TWOPAGES], *nl;

	while(argc>1 && argv[1][0]=='-'){
		for(i=1;argv[1][i];i++) switch(argv[1][i]){
		case 'n': nflag++; break;
		default:
		Usage:
			fprintf(stderr, "Usage: %s [-n] [file ...]\n", argv[0]);
			exit(1);
		}
		argv++;
		--argc;
	}
	if(argc==1){
		if((comfile=fopen(".comfile", "r"))==NULL) goto Usage;
		while(fgets(str, sizeof(str), comfile)!=NULL){
			nl=strchr(str, '\n');
			if(nl) *nl='\0';
			make(str);
		}
	}
	else{
		if(!nflag && (comfile=fopen(".comfile", "w"))!=NULL){
			for(i=1;i!=argc;i++) fprintf(comfile, "%s\n", argv[i]);
			fclose(comfile);
		}
		for(i=1;i!=argc;i++){ make(argv[i]);}
	}
	exit(maxstat);
}
void make(char filename[]){
	extern char command[];

	char *s, *t, *suffix;
	int c;
	FILE *f;
	int stat;

	FILE *ccdb;
	char *command_s;
	char *command_o;
	int command_i;



	if((f=fopen(filename, "r"))==NULL){
		warnx("%s", filename);
		if(maxstat<1) maxstat=1;
		return;
	}
	/*
	 * Look for /*%
	 */
	for(;;){
		c=getc(f);
		if(c==EOF){
			warn("%s: no command\n", filename);
			fclose(f);
			if(maxstat<1) maxstat=1;
			return;
		}
		if(c=='/'){
			if((c=getc(f))=='*' && (c=getc(f))=='%') break;
			ungetc(c, f);	/* might be another slash! */
		}
	}
	s=command;
	do;while((c=getc(f))==' ' || c=='\t');
	suffix=strrchr(filename, '.');
	if(suffix==NULL) suffix=filename+strlen(filename);
	while(c>=0 && c!='\n'){
		switch(c){
		default:
			*s++=c;
			break;
		case '%':
			c=getc(f);
			if(c=='%') *s++='%';
			else{
				ungetc(c, f);
				t=filename;
				while(*t) *s++ = *t++;
			}
			break;
		case '#':
			c=getc(f);
			if(c=='#') *s++='#';
			else{
				ungetc(c, f);
				t=filename;
				while(t!=suffix) *s++ = *t++;
			}
		}
		c=getc(f);
	}
	*s='\0';
	if(nflag){
		printf("%s\n", command);
		return;
	}


	fprintf(stderr, "%s\n", command);
	switch(fork()){
	case -1:
		err(1, "%s\n", "can't fork");

	case 0:
		execl("/bin/sh", "sh", "-c", command, NULL);
		err(1,"%s\n", "No shell!\n");
	default:
		wait(&stat);
		if(stat>maxstat) maxstat=stat;
		fclose(f);
	}

	if(!nflag){
		if ((ccdb = fopen("compile_flags.txt", "w")) == NULL)
			err(1, "%s\n", "can't open compile_flags.txt");

		command_s = command;
		command_i = 0;
		while((command_o = strsep(&command_s," \t"))!= NULL){
			if(command_i != 0)
				fprintf(ccdb, "%s\n", command_o);

			command_i++;
		}
		fclose(ccdb);

	}

}

/*
 * Copyright © 2022,2024 Artsiom Karakin
 * Copyright © 2002-2011 Tom Duff
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in the
 * Software without restriction, including without limitation the rights to use, copy,
 * modify, merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to the
 * following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */