/* * Concatenate files. */#include <stdio.h>#include <sys/types.h>#include <sys/stat.h>char	stdbuf[BUFSIZ];main(argc, argv)char **argv;{	int fflg = 0;	register FILE *fi;	register c;	int dev, ino = -1;	struct stat statb;	setbuf(stdout, stdbuf);	for( ; argc>1 && argv[1][0]=='-'; argc--,argv++) {		switch(argv[1][1]) {		case 0:			break;		case 'u':			setbuf(stdout, (char *)NULL);			continue;		}		break;	}	fstat(fileno(stdout), &statb);	statb.st_mode &= S_IFMT;	if (statb.st_mode!=S_IFCHR && statb.st_mode!=S_IFBLK) {		dev = statb.st_dev;		ino = statb.st_ino;	}	if (argc < 2) {		argc = 2;		fflg++;	}	while (--argc > 0) {		if (fflg || (*++argv)[0]=='-' && (*argv)[1]=='\0')			fi = stdin;		else {			if ((fi = fopen(*argv, "r")) == NULL) {				fprintf(stderr, "cat: can't open %s\n", *argv);				continue;			}		}		fstat(fileno(fi), &statb);		if (statb.st_dev==dev && statb.st_ino==ino) {			fprintf(stderr, "cat: input %s is output\n",			   fflg?"-": *argv);			fclose(fi);			continue;		}		while ((c = getc(fi)) != EOF)			putchar(c);		if (fi!=stdin)			fclose(fi);	}	return(0);}