awk:如果> = = 4行连续以+或 - 开头,则不打印记录

Question

我正在尝试使用awk来读取文件,并且只显示不以+或 - 4行或更多次开头的行.gawk也没关系.每个分组用空行分隔.

下面是该文件的样本,这些都是我行不希望打印:

+Host is up.
+Not shown: 95 closed ports, 3 filtered ports
+PORT     STATE SERVICE   VERSION
+23/tcp   open  telnet
+9100/tcp open  jetdirect

-Host is up.
-Not shown: 99 closed ports
-PORT     STATE SERVICE VERSION
-5900/tcp open  vnc

从该文件的样品,我不(在一行中不4个或更多)要打印:

-Not shown: 76 closed ports, 18 filtered ports
+Not shown: 93 closed ports
PORT    STATE SERVICE VERSION
+514/tcp open  shell

我正在学习如何使用awk,因为我一直在阅读O'Reilly的awk&sed,但我对这个问题感到有点困惑.此外,如果有人关心,我不介意看到使用shell脚本解决此问题的非awk方法.

谢谢!

Answer 1

如果我理解了您的问题,输入文件会将记录作为段落,因此您需要将它们用空行分隔.我认为它适用于下一个脚本:

内容script.awk:

BEGIN {
        ## Separate records by one or more blank lines.
        RS = ""

        ## Each line will be one field. Both for input and output.
        FS = OFS = "\n"
}

## For every paragraph...
{
        ## Flag to check if I will print the paragraph to output.
        ## If 1, print.
        ## If 0, don't print.
        output = 1

        ## Count how many consecutive rows have '+' or '-' as first
        ## character.
        j = 0

        ## Traverse all rows.
        for ( i = 1; i <= NF; i++ ) {
                if ( substr( $i, 1, 1 ) ~ /+|-/ ) {
                        ++j;
                }
                else {
                        j = 0
                }

                if ( j >= 4 ) {
                        output = 0
                        break
                }
        }

        if ( output == 1 ) {
                print $0 "\n"
        }
}

假设以下测试输入文件为infile:

+Host is up. 
+Not shown: 95 closed ports, 3 filtered ports
+PORT     STATE SERVICE   VERSION

+Host is up. 
+Not shown: 95 closed ports, 3 filtered ports
+PORT     STATE SERVICE   VERSION
+23/tcp   open  telnet
+9100/tcp open  jetdirect

-Host is up. 
-Not shown: 99 closed ports
-PORT     STATE SERVICE VERSION
-5900/tcp open  vnc 

-Not shown: 76 closed ports, 18 filtered ports
+Not shown: 93 closed ports
PORT    STATE SERVICE VERSION
+514/tcp open  shell

运行脚本如:

awk -f script.awk infile

使用以下输出(第一个记录,因为它没有达到连续四行,而第二个记录因为它们之间有不同的行):

+Host is up.
+Not shown: 95 closed ports, 3 filtered ports
+PORT     STATE SERVICE   VERSION

-Not shown: 76 closed ports, 18 filtered ports
+Not shown: 93 closed ports
PORT    STATE SERVICE VERSION
+514/tcp open  shell