centos 7.0 ln命令 和chkconfig 命令介绍 开机自动启 服务

[root@localhost ~]# ln --help
用法：ln [选项]... [-T] 目标 链接名     (第一种格式)
　或：ln [选项]... 目标         (第二种格式)
　或：ln [选项]... 目标... 目录 (第三种格式)
　或：ln [选项]... -t 目录 目标...      (第四种格式)
In the 1st form, create a link to TARGET with the name LINK_NAME.
In the 2nd form, create a link to TARGET in the current directory.
In the 3rd and 4th forms, create links to each TARGET in DIRECTORY.
Create hard links by default, symbolic links with --symbolic.
By default, each destination (name of new link) should not already exist.
When creating hard links, each TARGET must exist.  Symbolic links
can hold arbitrary text; if later resolved, a relative link is
interpreted in relation to its parent directory.

Mandatory arguments to long options are mandatory for short options too.
      --backup[=CONTROL]        为每个已存在的目标文件创建备份文件
  -b                            类似--backup，但不接受任何参数
  -d, -F, --directory           创建指向目录的硬链接(只适用于超级用户)
  -f, --force                   强行删除任何已存在的目标文件
  -i, --interactive           prompt whether to remove destinations
  -L, --logical               dereference TARGETs that are symbolic links
  -n, --no-dereference        treat LINK_NAME as a normal file if
                                it is a symbolic link to a directory
  -P, --physical              make hard links directly to symbolic links
  -r, --relative              create symbolic links relative to link location
  -s, --symbolic              make symbolic links instead of hard links
  -S, --suffix=SUFFIX         override the usual backup suffix
  -t, --target-directory=DIRECTORY  specify the DIRECTORY in which to create
                                the links
  -T, --no-target-directory   treat LINK_NAME as a normal file always
  -v, --verbose               print name of each linked file
      --help            显示此帮助信息并退出
      --version         显示版本信息并退出

The backup suffix is ‘~‘, unless set with --suffix or SIMPLE_BACKUP_SUFFIX.
The version control method may be selected via the --backup option or through
the VERSION_CONTROL environment variable.  Here are the values:

  none, off       不进行备份(即使使用了--backup 选项)
  numbered, t     备份文件加上数字进行排序
  existing, nil   若有数字的备份文件已经存在则使用数字，否则使用普通方式备份
  simple, never   永远使用普通方式备份

Using -s ignores -L and -P.  Otherwise, the last option specified controls
behavior when a TARGET is a symbolic link, defaulting to -P.

GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
请向<http://translationproject.org/team/zh_CN.html> 报告ln 的翻译错误
要获取完整文档，请运行：info coreutils ‘ln invocation‘
[root@localhost ~]#

[root@localhost ~]# chkconfig --list denyhosts

注意：该输出结果只显示 SysV 服务，并不包含原生 systemd 服务。SysV 配置数据可能被原生 systemd 配置覆盖。
      如果您想列出 systemd 服务,请执行 ‘systemctl list-unit-files‘。
      欲查看对特定 target 启用的服务请执行
      ‘systemctl list-dependencies [target]‘。

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