c - Linux命令中的更多选项和编译错误

我正在尝试在命令$ printenv中添加为选项date。例如如果尝试运行$ printenv -d，则应返回日期输出。

我有来自链接ftp://ftp.ntua.gr/pub/gnu/coreutils/coreutils-8.23.tar.xz的src代码，该链接包含linux发行版中的所有coreutils。

我已经更改了src / printenv.c的源代码（此文件位于coreutils.tar文件中）。但是我的下一步是什么？

我无法使用gcc printenv.c进行编译

Compile error: fatal error: config.h: No such file or directory
compilation terminated.

我应该制作makefiles / configs等并手动安装吗？怎么样？

我发布了更改的代码（printenv.c）

    /* printenv -- print all or part of environment
   Copyright (C) 1989-2014 Free Software Foundation, Inc.

   This program 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.

   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */

/* Usage: printenv [variable...]

   If no arguments are given, print the entire environment.
   If one or more variable names are given, print the value of
   each one that is set, and nothing for ones that are not set.

   Exit status:
   0 if all variables specified were found
   1 if not
   2 if some other error occurred

   David MacKenzie and Richard Mlynarik */

#include <config.h>
#include <stdio.h>
#include <sys/types.h>
#include <getopt.h>

#include "system.h"

/* Exit status for syntax errors, etc.  */
enum { PRINTENV_FAILURE = 2 };

/* The official name of this program (e.g., no 'g' prefix).  */
#define PROGRAM_NAME "printenv"

#define AUTHORS \
  proper_name ("David MacKenzie"), \
  proper_name ("Richard Mlynarik")

static struct option const longopts[] =
{
  {"null", no_argument, NULL, '0'},
  {"date", required_argument, NULL, 'd'},
  {GETOPT_HELP_OPTION_DECL},
  {GETOPT_VERSION_OPTION_DECL},
  {NULL, 0, NULL, 0}
};

/* Forward declarations.  */
static void dateMachine (void);

void
usage (int status)
{
  if (status != EXIT_SUCCESS)
    emit_try_help ();
  else
    {
      printf (_("\
Usage: %s [OPTION]... [VARIABLE]...\n\
Print the values of the specified environment VARIABLE(s).\n\
If no VARIABLE is specified, print name and value pairs for them all.\n\
\n\
"),
              program_name);
      fputs (_("\
  -0, --null     end each output line with NUL, not newline\n\
"), stdout);
      fputs (HELP_OPTION_DESCRIPTION, stdout);
      fputs (VERSION_OPTION_DESCRIPTION, stdout);
      printf (USAGE_BUILTIN_WARNING, PROGRAM_NAME);
      emit_ancillary_info ();
    }
  exit (status);
}

int
main (int argc, char **argv)
{
  char **env;
  char *ep, *ap;
  int i;
  bool ok;
  int optc;
  bool opt_nul_terminate_output = false;

  initialize_main (&argc, &argv);
  set_program_name (argv[0]);
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);

  initialize_exit_failure (PRINTENV_FAILURE);
  atexit (close_stdout);

  while ((optc = getopt_long (argc, argv, "+iu:0d", longopts, NULL)) != -1)
    {
      switch (optc)
        {
        case '0':
          opt_nul_terminate_output = true;
          break;
        case 'd':
          dateMachine ();
          break;
        case_GETOPT_HELP_CHAR;
        case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
        default:
          usage (PRINTENV_FAILURE);
        }
    }

  if (optind >= argc)
    {
      for (env = environ; *env != NULL; ++env)
        printf ("%s%c", *env, opt_nul_terminate_output ? '\0' : '\n');
      ok = true;
    }
  else
    {
      int matches = 0;

      for (i = optind; i < argc; ++i)
        {
          bool matched = false;

          /* 'printenv a=b' is silent, even if 'a=b=c' is in environ.  */
          if (strchr (argv[i], '='))
            continue;

          for (env = environ; *env; ++env)
            {
              ep = *env;
              ap = argv[i];
              while (*ep != '\0' && *ap != '\0' && *ep++ == *ap++)
                {
                  if (*ep == '=' && *ap == '\0')
                    {
                      printf ("%s%c", ep + 1,
                              opt_nul_terminate_output ? '\0' : '\n');
                      matched = true;
                      break;
                    }
                }
            }

          matches += matched;
        }

      ok = (matches == argc - optind);
    }

  exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
}

static void
dateMachine (void)
{
    system(date);
}

最佳答案

如果您在Google中搜索“ printenv.c”，则会发现该文件的多个版本，可以以最少的乱七八糟的方式进行编译和运行。

示例：“ http://www.opensource.apple.com/source/shell_cmds/shell_cmds-170/printenv/printenv.c”