view toys/posix/head.c @ 780:6cc69be43c42

Have error_msg() and friends set TT.exitval to 1 if it's still 0, clean out other places that were setting it that no longer need to.
author Rob Landley <>
date Wed, 02 Jan 2013 02:00:35 -0600
parents 786841fdb1e0
children 0c30e5484516
line wrap: on
line source

/* head.c - copy first lines from input to stdout.
 * Copyright 2006 Timothy Elliott <>
 * See

USE_HEAD(NEWTOY(head, "n#<0=10", TOYFLAG_BIN))

config HEAD
  bool "head"
  default y
    usage: head [-n number] [file...]

    Copy first lines from files to stdout. If no files listed, copy from
    stdin. Filename "-" is a synonym for stdin.

    -n	Number of lines to copy.

#define FOR_head
#include "toys.h"

  long lines;
  int file_no;

static void do_head(int fd, char *name)
  int i, len, lines=TT.lines, size=sizeof(toybuf);

  if (toys.optc > 1) {
    // Print an extra newline for all but the first file
    if (TT.file_no++) xprintf("\n");
    xprintf("==> %s <==\n", name);

  while (lines) {
    len = read(fd, toybuf, size);
    if (len<0) perror_msg("%s",name);
    if (len<1) break;

    for(i=0; i<len;) if (toybuf[i++] == '\n' && !--lines) break;

    xwrite(1, toybuf, i);

void head_main(void)
  loopfiles(toys.optargs, do_head);