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/* head - copy first part of files. */
/* See Makefile for compilation details. */
/*
Copyright (C) 1999-2009 Free Software Foundation, Inc.
This file is part of GNU Bash.
Bash is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Bash is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Bash. If not, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include "bashtypes.h"
#include "posixstat.h"
#include "filecntl.h"
#if defined (HAVE_UNISTD_H)
# include <unistd.h>
#endif
#include "bashansi.h"
#include <stdio.h>
#include <errno.h>
#include "chartypes.h"
#include "builtins.h"
#include "shell.h"
#include "bashgetopt.h"
#include "common.h"
#if !defined (errno)
extern int errno;
#endif
static void
munge_list (list)
WORD_LIST *list;
{
WORD_LIST *l, *nl;
WORD_DESC *wd;
char *arg;
for (l = list; l; l = l->next)
{
arg = l->word->word;
if (arg[0] != '-' || arg[1] == '-' || (DIGIT(arg[1]) == 0))
return;
/* We have -[0-9]* */
wd = make_bare_word (arg+1);
nl = make_word_list (wd, l->next);
l->word->word[1] = 'n';
l->word->word[2] = '\0';
l->next = nl;
l = nl; /* skip over new argument */
}
}
static int
file_head (fp, cnt)
FILE *fp;
int cnt;
{
int ch;
while (cnt--)
{
while ((ch = getc (fp)) != EOF)
{
if (putchar (ch) == EOF)
{
builtin_error ("write error: %s", strerror (errno));
return EXECUTION_FAILURE;
}
if (ch == '\n')
break;
}
}
return (EXECUTION_SUCCESS);
}
int
head_builtin (list)
WORD_LIST *list;
{
int nline, opt, rval;
WORD_LIST *l;
FILE *fp;
char *t;
munge_list (list); /* change -num into -n num */
reset_internal_getopt ();
nline = 10;
while ((opt = internal_getopt (list, "n:")) != -1)
{
switch (opt)
{
case 'n':
nline = atoi (list_optarg);
if (nline <= 0)
{
builtin_error ("bad line count: %s", list_optarg);
return (EX_USAGE);
}
break;
CASE_HELPOPT;
default:
builtin_usage ();
return (EX_USAGE);
}
}
list = loptend;
if (list == 0)
return (file_head (stdin, nline));
for (rval = EXECUTION_SUCCESS, opt = 1, l = list; l; l = l->next)
{
fp = fopen (l->word->word, "r");
if (fp == NULL)
{
builtin_error ("%s: %s", l->word->word, strerror (errno));
continue;
}
if (list->next) /* more than one file */
{
printf ("%s==> %s <==\n", opt ? "" : "\n", l->word->word);
opt = 0;
}
rval = file_head (fp, nline);
fclose (fp);
}
return (rval);
}
char *head_doc[] = {
"Display lines from beginning of file.",
"",
"Copy the first N lines from the input files to the standard output.",
"N is supplied as an argument to the `-n' option. If N is not given,",
"the first ten lines are copied.",
(char *)NULL
};
struct builtin head_struct = {
"head", /* builtin name */
head_builtin, /* function implementing the builtin */
BUILTIN_ENABLED, /* initial flags for builtin */
head_doc, /* array of long documentation strings. */
"head [-n num] [file ...]", /* usage synopsis; becomes short_doc */
0 /* reserved for internal use */
};
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