uniq.c

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/* uniq - compact repeated lines                Author: John Woods */
/* Uniq [-udc] [-n] [+n] [infile [outfile]]
 *
 *      Written 02/08/86 by John Woods, placed into public domain.  Enjoy.
 *
 */

/* If the symbol WRITE_ERROR is defined, uniq will exit(1) if it gets a
 * write error on the output.  This is not (of course) how V7 uniq does it,
 * so undefine the symbol if you want to lose your output to a full disk
 */

#define WRITE_ERROR 1
#include <ctype.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>

char buffer[BUFSIZ];
int uflag = 1;                  /* default is union of -d and -u outputs */
int dflag = 1;                  /* flags are mutually exclusive */
int cflag = 0;
int fields = 0;
int chars = 0;

_PROTOTYPE(int main, (int argc, char **argv));
_PROTOTYPE(FILE *xfopen, (char *fn, char *mode));
_PROTOTYPE(char *skip, (char *s));
_PROTOTYPE(int equal, (char *s1, char *s2));
_PROTOTYPE(void show, (char *line, int count));
_PROTOTYPE(int uniq, (void));
_PROTOTYPE(void usage, (void));
_PROTOTYPE(int getline, (char *buf, int count));

FILE *xfopen(fn, mode)
char *fn, *mode;
{
  FILE *p;

  if ((p = fopen(fn, mode)) == NULL) {
        perror("uniq");
        fflush(stdout);
        exit(1);
  }
  return(p);
}

int main(argc, argv)
int argc;
char *argv[];
{
  char *p;
  int inf = -1, outf;

  setbuf(stdout, buffer);
  for (--argc, ++argv; argc > 0 && (**argv == '-' || **argv == '+');
       --argc, ++argv) {
        if (**argv == '+')
                chars = atoi(*argv + 1);
        else if (isdigit(argv[0][1]))
                fields = atoi(*argv + 1);
        else if (argv[0][1] == '\0')
                inf = 0;        /* - is stdin */
        else
                for (p = *argv + 1; *p; p++) {
                        switch (*p) {
                            case 'd':
                                dflag = 1;
                                uflag = 0;
                                break;
                            case 'u':
                                uflag = 1;
                                dflag = 0;
                                break;
                            case 'c':   cflag = 1;      break;
                            default:    usage();
                        }
                }
  }

  /* Input file */
  if (argc == 0)
        inf = 0;
  else if (inf == -1) {         /* if - was not given */
        fclose(stdin);
        xfopen(*argv++, "r");
        argc--;
  }
  if (argc == 0)
        outf = 1;
  else {
        fclose(stdout);
        xfopen(*argv++, "w");
        argc--;
  }

  uniq();
  fflush(stdout);
  return(0);
}

char *skip(s)
char *s;
{
  int n;

  /* Skip fields */
  for (n = fields; n > 0; --n) {
        /* Skip blanks */
        while (*s && (*s == ' ' || *s == '\t')) s++;
        if (!*s) return s;
        while (*s && (*s != ' ' && *s != '\t')) s++;
        if (!*s) return s;
  }

  /* Skip characters */
  for (n = chars; n > 0; --n) {
        if (!*s) return s;
        s++;
  }
  return s;
}

int equal(s1, s2)
char *s1, *s2;
{
  return !strcmp(skip(s1), skip(s2));
}

void show(line, count)
char *line;
int count;
{
  if (cflag)
        printf("%4d %s", count, line);
  else {
        if ((uflag && count == 1) || (dflag && count != 1))
                printf("%s", line);
  }
}

/* The meat of the whole affair */
char *nowline, *prevline, buf1[1024], buf2[1024];

int uniq()
{
  char *p;
  int seen;

  /* Setup */
  prevline = buf1;
  if (getline(prevline, 1024) < 0) return(0);
  seen = 1;
  nowline = buf2;

  /* Get nowline and compare if not equal, dump prevline and swap
   * pointers else continue, bumping seen count */
  while (getline(nowline, 1024) > 0) {
        if (!equal(prevline, nowline)) {
                show(prevline, seen);
                seen = 1;
                p = nowline;
                nowline = prevline;
                prevline = p;
        } else
                seen += 1;
  }
  show(prevline, seen);
  return 0;
}

void usage()
{
  fprintf(stderr, "Usage: uniq [-udc] [+n] [-n] [input [output]]\n");
}

int getline(buf, count)
char *buf;
int count;
{
  int c;
  int ct = 0;

  while (ct++ < count) {
        c = getc(stdin);
        if (c < 0) return(-1);
        *buf++ = c;
        if (c == '\n') {
                *buf++ = 0;
                return(ct);
        }
  }
  return(ct);
}

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