sed或perl regex替换文件中的部分

Question

I have a file, and am trying to regex to remove the the lines that has:

flannel:
    interface: $private_ipv4
    etcd_endpoints: {{ .ETCDEndpoints }}

I tried to to use this perl command, it ends up removing everything from #cloud-config till -- name: docker.service

perl -i -00ne 'print unless /(flannel:).*([^ ]+).*([^ ]+).*}}/' file.txt

file.txt:

#cloud-config
coreos:
  update:
    reboot-strategy: "off"
  flannel:
    interface: $private_ipv4
    etcd_endpoints: {{ .ETCDEndpoints }}
  etcd2:
    name: controller
    advertise-client-urls: http://$private_ipv4:2379
    initial-advertise-peer-urls: http://$private_ipv4:2380
    listen-client-urls: http://0.0.0.0:2379
    listen-peer-urls: http://0.0.0.0:2380
    initial-cluster: controller=http://$private_ipv4:2380
  units:
    - name: etcd2.service
      command: start
      runtime: true

    - name: docker.service
      drop-ins:
        - name: 40-flannel.conf
          content: |
            [Unit]
            Requires=flanneld.service
            After=flanneld.service
            [Service]
            EnvironmentFile=/etc/kubernetes/cni/docker_opts_cni.env
            ...

Answer 1

Given the exact text you show

perl -0777 -ne 's/flannel:[^}]+}//; print' file.txt

This works by observation that there is no } inside the text to be removed. It thus uses the negated character class , [^}] which matches any character other than } . So with + it matches all up to the first } . See this in perlretut and in perlrecharclass . Please adjust for other text.

Or use

perl -0777 -ne 's/flannel:.+?(?=etcd2:)+//s; print' file.txt

which uses the positive lookahead (?=...) . It is a zero width assertion , meaning that it matches up to that pattern and does not consume it. It just "looks" (asserts) that it's there. See it in perlretut . In this case we also need the modifier /s , which makes . match the newline, too.

The -0[oct/hex] switch sets the input record separator $/ . The -00 sets it to an empty line thus reading by paragraphs, which isn't what you need. The -0 splits input by null character, which is very unlikely to be in a file so it normally "works" for reading the whole file at once. But a proper way to slurp a file is to specify anything greater than -0400 and -0777 is customary. See Command line switches in perlrun

Here you can use -p instead of -n and then drop print , since -p prints $_ .

Answer 2

In your command line spec -00ne , you are asking for 'paragraph' mode (two zeros). I think you want to slurp the file if I'm understanding your problem correctly. That would use one zero.

I used perl -0777 -pe 's/^\\s+flannel:.+?(?=^\\s+etcd2)//ms' file.txt to get what I think you want:

Note the flags ms . m makes the ^ match at the beginning of a 'line' instead of the default behavior of matching at the beginning of a 'string'. And the s flag allows dot (.) to also match newlines which is needed in the solution I gave.

#cloud-config
coreos:
  update:
    reboot-strategy: "off"
  etcd2:
    name: controller
    advertise-client-urls: http://$private_ipv4:2379
    initial-advertise-peer-urls: http://$private_ipv4:2380
    listen-client-urls: http://0.0.0.0:2379
    listen-peer-urls: http://0.0.0.0:2380
    initial-cluster: controller=http://$private_ipv4:2380
  units:
    - name: etcd2.service
      command: start
      runtime: true

    - name: docker.service
      drop-ins:
        - name: 40-flannel.conf
          content: |
            [Unit]
            Requires=flanneld.service
            After=flanneld.service
            [Service]
            EnvironmentFile=/etc/kubernetes/cni/docker_opts_cni.env

Answer 3

It's YAML so use a YAML parser.

#!/usr/bin/env perl
use strict;
use warnings;

use YAML::XS;
use Data::Dumper;

# <> is the magic file handle, it reads files on command line or STDIN. 
# much like grep/sed/awk do.     
my $conf = Load ( do { local $/; <> } );
#print for debugging. 
print Dumper $conf;

#delete the key you don't want. 
delete $conf->{coreos}{flannel};

#print output to STDOUT. 
#You can hack this into in place editing if you
#want. 
print Dump $conf;