我正在执行以下awk
命令:
egrep '^[0-9]' /etc/hosts | grep -v 127.0.0.1
| awk 'NR==1{ips=$1}
NR>1{ips=ips ", " $1}
$2=="namenode"{nn=$1}
END{ printf "/opt/mapr/server/configure.sh -C %s -Z %s -N mycluster --create-user -D /dev/xvdb", ips, nn}'
并返回正确的输出:
/opt/mapr/server/configure.sh -C 10.224.43.50, 10.40.235.23 -Z 10.40.235.23 -N mycluster --create-user -D /dev/xvdb
现在我变得更聪明了,并尝试遵循以下模式:
egrep '^[0-9]' /etc/hosts | grep -v 127.0.0.1
| awk 'NR==1{ips=$1}
NR>1{ips=ips ", " $1}
$2=="namenode"{nn=$1}
END{ printf "/opt/mapr/server/configure.sh -C %s -Z %s -RM %s -HS %s -N mycluster --create-user -D /dev/xvdb", ips, nn, nn, nn}'
就是这样,我又添加了两个具有相同值nn
的条目,但一无所获。为什么?
这是/etc/hosts
:的示例
root@ip-10-40-235-23:~# cat /etc/hosts
127.0.0.1 localhost
# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts
## vagrant-hostmanager-start
10.224.43.50 dgnode dgnode.dg.local
10.40.235.23 namenode namenode.dg.local
## vagrant-hostmanager-end
去掉不必要的grep和管道,并将其写成:
$ cat tst.awk
/^[0-9]/ && !/127.0.0.1/ {
ips = (ips ? ips ", " : "") $1
if ($2=="namenode") {
nn = $1
}
}
END {
printf "/opt/mapr/server/configure.sh -C %s -Z %s -RM %s -HS %s -N mycluster --create-user -D /dev/xvdbn", ips, nn, nn, nn
}
$ awk -f tst.awk file
/opt/mapr/server/configure.sh -C 10.224.43.50, 10.40.235.23 -Z 10.40.235.23 -RM 10.40.235.23 -HS 10.40.235.23 -N mycluster --create-user -D /dev/xvdb
我已经尝试了您的两个命令管道,并在这两个管道中都获得了输出。第二个命令管道也不会像您在问题中提到的那样产生空白输出。
但是,您可以让awk
完成所有工作,并将egrep
完全从您的命令中删除:
awk '/127.0.0.1/ || !/^[0-9]/{next}
!ips{ips=$1; next}
{ips=ips ", " $1}
$2=="namenode"{nn=$1}
END{ printf "/opt/mapr/server/configure.sh -C %s -Z %s -RM %s -HS %s -N mycluster --create-user -D /dev/xvdb", ips, nn, nn, nn
}' /etc/hosts