使 awk 打印单行的特定段

Question

我有一个名为 LogsDocker 的文件，其中包含

export DOCKER_TLS_VERIFY="1"
export DOCKER_HOST="tcp://192.168.99.100:2376"
export DOCKER_CERT_PATH="/root/.docker/machine/machines/Main-hola"
export DOCKER_MACHINE_NAME="Main-hola"
# Run this command to configure your shell: 
# eval $(docker-machine env Main-hola)

我只想打印ip

192.168.99.100

刚刚发现了 awk 和命令

 awk 'BEGIN { FS = "//"} ; { print $2}' LogsDocker

使它打印（带有一堆空行）

192.168.99.100:2376"

只打印没有空行的 ip 的正确方法是什么

Answer 1

你能不能试试以下。

awk '/DOCKER_HOST/ && match($0,/[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/){print substr($0,RSTART,RLENGTH)}' Input_file

说明：为上述代码添加说明。

awk '                                                             ##Starting awk program from here.
/DOCKER_HOST/ && match($0,/[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/){      ##Checking condition if string DOCKER_HOST is found in line AND match is having a mentioned regex matched in it.
  print substr($0,RSTART,RLENGTH)                                 ##If above conditions are TRUE then printing substring whose starting index is RSTART and ending index is RLENGTH.
}
' Input_file                                                      ##Mentioning Input_file name here.

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第二种解决方案：考虑到您的 Input_file 将始终相同，然后尝试遵循。

awk -F'[/:]' '/DOCKER_HOST/{print $4}' Input_file

说明：为上述代码添加说明。

awk -F'[/:]' '      ##Starting awk program from here and setting field separator as /or colon here.
/DOCKER_HOST/{      ##Checking condition if a line has string DOCKER_HOST then do following.
  print $4          ##Printing 4th field of current line.
}
' Input_file        ##Mentioning Input_file name here.

---

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第三种解决方案： sed解决方案。

sed -n '/DOCKER_HOST/s/.*\///;s/:.*//p'  Input_file

说明：以下仅作说明之用。

sed -n '          ##Starting sed program from here and making printing off for all lines until specifically mentioned.
/DOCKER_HOST/     ##Searching string DOCKER_HOST in lines if present then do following.
s/                ##s means perform substitution operation here.
.*\/              ##mentioning regex which covers everything till / in line, if matched this regex
//                ##Then substitute it with NULL here.
;                 ##semi colon denotes to segregate another substitute operation after this one.
s/                ##Doing substitution from here.
:.*               ##Match everything from : to till last of line.
//                ##Substitute above matched values with NULL in current line.
p                 ##p means only print this line.
'  Input_file     ##Mentioning Input_file name here.

Answer 2

假设给定您现有的代码，IP 地址是您拥有的唯一位置// ：

$ awk 'sub(/.*\/\//,""){sub(/:.*/,""); print}' file
192.168.99.100

或做出其他假设...：

$ awk -F'//|:' 'NF>2{print $3}' file
192.168.99.100

或者：

$ awk -F'//|:' '/DOCKER_HOST=/{print $3}' file
192.168.99.100

或者 ....

这实际上只取决于该文件中还有什么内容以及您希望它有多健壮。