bash源代码分析----login shell登录shell和interactive交互式shell的关系以及main函数中的change_flag_char函数

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我是靠谱客的博主狂野诺言，最近开发中收集的这篇文章主要介绍bash源代码分析----login shell登录shell和interactive交互式shell的关系以及main函数中的change_flag_char函数，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

/* Non-zero means that this shell is a login shell.
   Specifically:
   0 = not login shell.
   1 = login shell from getty (or equivalent fake out)
-1 = login shell from "-login" flag.
-2 = both from getty, and from flag.
*/
int login_shell = -2;

/* Non-zero means this shell is running interactively. */
int interactive = 0;

main (argc, argv, env)
int argc;
char **argv, **env;
{

......

/* All done with full word args; do standard shell arg parsing.*/
while (arg_index != argc && argv[arg_index] &&
   (*(argv[arg_index]) == '-' || (*argv[arg_index] == '+')))
    {
      /* There are flag arguments, so parse them. */
      int arg_character;
      int on_or_off = (*argv[arg_index]);
      int i = 1;

      while (arg_character = (argv[arg_index])[i++])
   {
      switch (arg_character)
        {
        case 'c':
          /* The next arg is a command to execute, and the following args
       are $1 .. $n respectively. */
          local_pending_command = argv[++arg_index];
          if (!local_pending_command)
       {
          report_error ("`%cc' requires an argument", on_or_off);
          exit (1);
       }

          arg_index++;
          goto after_flags;
          break;

        default:
          if (change_flag_char (arg_character, on_or_off) == FLAG_ERROR)
       {
          report_error ("%c%c: bad option", on_or_off, arg_character);
          exit (1);
       }

        }
   }
      arg_index++;
    }

after_flags:

/* First, let the outside world know about our interactive status. */
if (forced_interactive ||
      (!local_pending_command &&
       arg_index == argc &&
       isatty (fileno (stdin)) &&
       isatty (fileno (stdout))))
    interactive = 1;
else
    {
      interactive = 0;
#ifdef JOB_CONTROL
      job_control = 0;
#endif
    }