BSD 4 release

[unix-history] / usr / src / cmd / head.c

static char *sccsid = "@(#)head.c       4.1 (Berkeley) 10/1/80";
#include <stdio.h>
/*
* head - give the first few lines of a stream or of each of a set of files
*
* Bill Joy UCB August 24, 1977
*/

int     linecnt = 10;
int     argc;

main(Argc, argv)
       int Argc;
       char *argv[];
{
       register int argc;
       char *name;
       register char *argp;
       static int around;
       char obuf[BUFSIZ];

       setbuf(stdout, obuf);
       Argc--, argv++;
       argc = Argc;
       do {
               while (argc > 0 && argv[0][0] == '-') {
                       linecnt = getnum(argv[0] + 1);
                       argc--, argv++, Argc--;
               }
               if (argc == 0 && around)
                       break;
               if (argc > 0) {
                       close(0);
                       if (freopen(argv[0], "r", stdin) == NULL) {
                               perror(argv[0]);
                               exit(1);
                       }
                       name = argv[0];
                       argc--, argv++;
               } else
                       name = 0;
               if (around)
                       putchar('\n');
               around++;
               if (Argc > 1 && name)
                       printf("==> %s <==\n", name);
               copyout(linecnt);
               fflush(stdout);
       } while (argc > 0);
}

copyout(cnt)
       register int cnt;
{
       register int c;
       char lbuf[BUFSIZ];

       while (cnt > 0 && fgets(lbuf, sizeof lbuf, stdin) != 0) {
               printf("%s", lbuf);
               fflush(stdout);
               cnt--;
       }
}

getnum(cp)
       register char *cp;
{
       register int i;

       for (i = 0; *cp >= '0' && *cp <= '9'; cp++)
               i *= 10, i += *cp - '0';
       if (*cp) {
               fprintf(stderr, "Badly formed number\n");
               exit(1);
       }
       return (i);
}