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从阵列中删除 ssh 失效的主机

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从阵列中删除 ssh 失效的主机

有人可以解释一下为什么“s”和“localhot”保留在最终的主机列表中吗？

“s”仍然存在，尽管它已被删除......

$ HOSTLIST="localhost sdfsd sdfs s fsdf localhost sdfs fsdf sdf 127.0.0.1"
$ for h in ${HOSTLIST};do { timeout 3 bash -c "</dev/tcp/${h}/22" 2>/dev/null; } || { echo removing $h from HOSTLIST;HOSTLIST=${HOSTLIST[@]/${h}}; };done ; echo final HOSTLIST :: ${HOSTLIST}
removing sdfsd from HOSTLIST
removing sdfs from HOSTLIST
removing s from HOSTLIST
removing fsdf from HOSTLIST
removing sdfs from HOSTLIST
removing fsdf from HOSTLIST
removing sdf from HOSTLIST
final HOSTLIST :: localhot s localhost 127.0.0.1
$
$ telnet s 22
telnet: s: Name or service not known
s: Host name lookup failure
$ telnet localhot 22
telnet: localhot: Name or service not known
localhot: Host name lookup failure
$

答案1

删除时，您删除字符串中的s第一个。这可能不是您想要删除的（输出中的通知）。s$HOSTLISTslocalhot

更好地使用数组并构造一个好的主机数组，也许类似

hostlist=( localhost sdfsd sdfs s fsdf localhost sdfs fsdf sdf 127.0.0.1 )

for h in "${hostlist[@]}"; do
    if timeout 3 bash -c "</dev/tcp/$h/22" 2>/dev/null; then
       ok+=( "$h" )
    fi
done

printf 'Ok host: %s\n' "${ok[@]}"

答案2

您还可以通过迭代来完成此操作指数数组 ( ${!hostlist[@]}，注意!) 而不是价值观( ${hostlist[@]})，然后使用unset删除不需要的数组索引。

例如，基于@Kusalananda 的回答：

hostlist=( localhost sdfsd sdfs s fsdf localhost sdfs fsdf sdf 127.0.0.1 )

for h in "${!hostlist[@]}"; do
  if ! timeout 3 bash -c "</dev/tcp/${hostlist[$h]}/22" 2>/dev/null; then
   unset hostlist[$h]
  fi
done

printf 'Ok hosts: %s\n' "${hostlist[@]}"

或者，如果您已netcat安装，则可以使用内置的ncbash 来代替（对于每个主机来说，应该比 fork 快一点）：/dev/tcptimeoutbash

hostlist=( localhost sdfsd sdfs s fsdf localhost sdfs fsdf sdf 127.0.0.1 )

for h in "${!hostlist[@]}"; do
  if ! nc -w 3 "${hostlist[$h]}" 22 >& /dev/null; then
   unset hostlist[$h]
  fi
done

printf 'Ok hosts: %s\n' "${hostlist[@]}"

如果您不需要在if/then语句中执行任何其他操作，则可以进一步缩短它：

hostlist=( localhost sdfsd sdfs s fsdf localhost sdfs fsdf sdf 127.0.0.1 )

for h in "${!hostlist[@]}"; do
  nc -w 3 "${hostlist[$h]}" 22 >& /dev/null || unset hostlist[$h]
done

printf 'Ok hosts: %s\n' "${hostlist[@]}"

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