bash -c 和非交互式 shell

Question 1

我做了一些调查。根据bash的源码。

长话短说

非交互式 shell 是如何定义的？

缺少命令历史记录
不支持工作
没有行编辑功能
错误获取行号
没有提示
第一次错误后停止执行

bash -c（没有附加 -i 选项）是否总是创建非交互式 shell？

是的

更长的版本。

当 bash 接收到选项时调用该函数-c。

no_line_editing = 1意味着您无法使用退格键编辑命令。

bash_history_reinit (0);禁用历史记录和命令自动完成。

static void
init_noninteractive ()
{
#if defined (HISTORY)
  bash_history_reinit (0);
#endif /* HISTORY */
  interactive_shell = startup_state = interactive = 0;
  expand_aliases = posixly_correct; /* XXX - was 0 not posixly_correct */
  no_line_editing = 1;
#if defined (JOB_CONTROL)
  /* Even if the shell is not interactive, enable job control if the -i or
     -m option is supplied at startup. */
  set_job_control (forced_interactive||jobs_m_flag);
#endif /* JOB_CONTROL */
}

默认情况下，作业控制处于禁用状态，除非您强制使用-m

 /* We can only have job control if we are interactive unless we                      
force it. */

  if (interactive == 0 && force == 0)
    {
      job_control = 0;
      original_pgrp = NO_PID;
      shell_tty = fileno (stderr);
    }

语法错误消息包含行号。

/* Report a syntax error with line numbers, etc.
   Call here for recoverable errors.  If you have a message to print,
   then place it in MESSAGE, otherwise pass NULL and this will figure
   out an appropriate message for you. */
static void
report_syntax_error (message)
     char *message;
{
...
if (interactive == 0)
print_offending_line ();
...
}

简单测试

root@test:~# ;;
-bash: syntax error near unexpected token `;;'
root@test:~# bash -c ';;'
bash: -c: line 0: syntax error near unexpected token `;;'
bash: -c: line 0: `;;'

命令执行后不打印提示。

/* Issue a prompt, or prepare to issue a prompt when the next character
   is read. */
static void
prompt_again ()
{
  char *temp_prompt;

  if (interactive == 0 || expanding_alias ())   /* XXX */
    return;

命令执行在第一次错误后停止。

  /* Parse error, maybe discard rest of stream if not interactive. */
      if (interactive == 0)
        EOF_Reached = EOF;

Answer