查看系统命令的手册页

man <command>

这将显示指定命令的手册页。

例如，man ping 将显示：

`PING(8)`                   BSD System Manager's Manual                  `PING(8)`

NAME
     ping -- send ICMP ECHO_REQUEST packets to network hosts

SYNOPSIS
     ping [-AaCDdfnoQqRrv] [-b boundif] [-c count] [-G sweepmaxsize]
          [-g sweepminsize] [-h sweepincrsize] [-i wait] [-k trafficclass]
          [-l preload] [-M mask | time] [-m ttl] [-P policy] [-p pattern]
          [-S src_addr] [-s packetsize] [-t timeout] [-W waittime] [-z tos]
          host
     ping [-AaDdfLnoQqRrv] [-b boundif] [-c count] [-I iface] [-i wait]
          [-k trafficclass] [-l preload] [-M mask | time] [-m ttl] [-P policy]
          [-p pattern] [-S src_addr] [-s packetsize] [-T ttl] [-t timeout]
          [-W waittime] [-z tos] mcast-group

DESCRIPTION
     The ping utility uses the ICMP protocol's mandatory ECHO_REQUEST datagram
     to elicit an ICMP ECHO_RESPONSE from a host or gateway.  ECHO_REQUEST
     datagrams (``pings'') have an IP and ICMP header, followed by a ``struct
     timeval'' and then an arbitrary number of ``pad'' bytes used to fill out
     the packet.  The options are as follows:

...

在查看联机帮助页时，可以搜索它。键入斜杠（/）后跟搜索词将跳转到该术语的第一个出现。示例：/ping

之后按 N 将跳到下一次出现。Shift+N 将跳转到上一次发生。