为什么我检查端口占用时命令失败？

Question

我在网上搜索并使用了这个代码：

netstat –apn | grep 8080

它返回了这样的输出：

 [root@myserver ~]# netstat –apn | grep 8080
 usage: netstat [-veenNcCF] [<Af>] -r         netstat {-V|--version|-h|--help}
   netstat [-vnNcaeol] [<Socket> ...]
   netstat { [-veenNac] -I[<Iface>] | [-veenNac] -i | [-cnNe] -M | -s } [del                                                                                                             ay]

    -r, --route                display routing table
    -I, --interfaces=<Iface>   display interface table for <Iface>
    -i, --interfaces           display interface table
    -g, --groups               display multicast group memberships
    -s, --statistics           display networking statistics (like SNMP)
    -M, --masquerade           display masqueraded connections

    -v, --verbose              be verbose
    -n, --numeric              don't resolve names
    --numeric-hosts            don't resolve host names
    --numeric-ports            don't resolve port names
    --numeric-users            don't resolve user names
    -N, --symbolic             resolve hardware names
    -e, --extend               display other/more information
    -p, --programs             display PID/Program name for sockets
    -c, --continuous           continuous listing

    -l, --listening            display listening server sockets
    -a, --all, --listening     display all sockets (default: connected)
    -o, --timers               display timers
    -F, --fib                  display Forwarding Information Base (default)
    -C, --cache                display routing cache instead of FIB
    -T, --notrim               stop trimming long addresses
    -Z, --context              display SELinux security context for sockets

<Iface>: Name of interface to monitor/list.
<Socket>={-t|--tcp} {-u|--udp} {-S|--sctp} {-w|--raw} {-x|--unix} --ax25 --ipx                                                                                                                 --netrom
<AF>=Use '-A <af>' or '--<af>'; default: inet
List of possible address families (which support routing):
inet (DARPA Internet) inet6 (IPv6) ax25 (AMPR AX.25)
netrom (AMPR NET/ROM) ipx (Novell IPX) ddp (Appletalk DDP)
x25 (CCITT X.25)

我的命令有什么问题？

Answer 1

你的连字符实际上是一个破折号，它实际上应该是一个连字符。

你能看出区别：

右：

netstat -apn | grep 8080

错误：

netstat –apn | grep 8080

为什么我检查端口占用时命令失败？

Why does my command fail when I check port occupancy?

linux

bash

centos

centos6.5