我可以阻止“service foo status”通过“less”对其输出进行分页吗？

Question

你如何阻止命令service <name> status使用less在它的输出？

我有一个脚本可以自动执行一些 sysadmin 操作，在我将服务器升级到 Ubuntu 16.04 后，它中断了，因为检查服务状态的操作被阻塞，因为它使用类似less显示输出的东西，特别是supervisor服务。

我有几个守护进程配置为运行，当运行时sudo service supervisor status，我得到：

* supervisor.service - Supervisor process control system for UNIX
   Loaded: loaded (/lib/systemd/system/supervisor.service; disabled; vendor preset: enabled)
   Active: active (running) since Mon 2017-02-06 20:35:34 EST; 12h ago
     Docs: http://supervisord.org
  Process: 18476 ExecStop=/usr/bin/supervisorctl $OPTIONS shutdown (code=exited, status=0/SUCCESS)
 Main PID: 20228 (supervisord)
   CGroup: /system.slice/supervisor.service
           |- 7387 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7388 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7389 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7390 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7391 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7392 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7393 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7394 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7395 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7396 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7397 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7398 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7678 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7679 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7680 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7681 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7682 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7683 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7684 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7685 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7693 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7694 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7698 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7702 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7703 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7705 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7707 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7709 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7710 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7712 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7713 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7717 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7720 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7723 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7724 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7728 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7730 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7731 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7733 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7734 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7735 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7738 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7743 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7747 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7748 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7750 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7752 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7756 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7758 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7761 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7763 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7764 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7772 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7781 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7785 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7794 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7799 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7801 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
           |- 7805 /usr/local//myproject/.env/bin/python2.7 /usr/local//myproject/.env/bin/celery worker -A /myproject -l info --autoreload
lines 1-66

它不会返回，直到我手动向下滚动或按Q退出。如何禁用此功能？

Answer 1

Ubuntu 是一个 systemd 系统，其中service status命令实际上调​​用systemctl status，并且systemctl有一个--no-pager选项可以完全满足您的要求。因此，您最好systemctl在脚本中使用直接命令。

sudo systemctl --no-pager status supervisor

环境变量 SYSTEMD_PAGER

正如@jwodder 所指出的，另一种方法是设置SYSTEMD_PAGER环境变量。这还有一个额外的好处，即还会影响systemctl被另一个应用程序调用时的输出，例如service.

export SYSTEMD_PAGER=
sudo service supervisor status

将使您达到相同的输出。

Answer 2

如果检测到它的输出不是终端，less 通常会关闭它的寻呼机模式。因此，您可以尝试通过运行以下命令来使命令的输出不是终端：

sudo service supervisor status | cat

Answer 3

来自man systemctl：

ENVIRONMENT
...
   $SYSTEMD_PAGER
       Pager to use when --no-pager is not given; overrides $PAGER.
       Setting this to an empty string or the value "cat" is equivalent to
       passing --no-pager.

   $SYSTEMD_LESS
       Override the default options passed to less ("FRSXMK").

因此，在您的环境初始化中的某处，设置：

SYSTEMD_PAGER=

Answer 4

您还需要修改您的sudoers文件：

 Defaults        env_keep += "SYSTEMD_PAGER"