I want to write a program to change systems ip address from dhcp/static to static only. my original file’s contents will be either this
some initial text[ipv6]method=auto[ipv4]method=staticdns=8.8.8.8;addresses1=192.168.1.10;24;192.168.1.1;or it may be like this,
some initial text[ipv6]method=auto[ipv4]method=autoNow, i want to change after [ipv4] pattern, so that after editing my file should looks like this
some initial text[ipv6]method=auto[ipv4]method=staticdns=8.8.8.8;4.4.4.4;addresses1=192.168.1.20;24;192.168.1.1;Advertisement
Answer
Here’s a Perl solution. It sets the record delimiter to 2 newlines, so paragraphs are read. If the paragraph contains [ipv4], replace the input with the replacement. Replace data with the name of your file, or with "$@" and make it into a shell script. Add -i as an option to Perl if you want to overwrite files (don’t do that until you’ve tested it).
perl -pe 'my $replacement = qq"[ipv4]n" . "method=staticn" . "dns=8.8.8.8;4.4.4.4;n" . "addresses1=192.168.1.20;24;192.168.1.1;nn";$/ = "nn";$_ = $replacement if (m/^[ipv4]$/m);' dataThere are many alternative ways of writing that code; I make no claims other than “it works for me”.
Given the text of your question as the input, the output is:
I want to write a program to change systems ip address from dhcp/static to static only. my original file's contents will be either thissome initial text[ipv6]method=auto[ipv4]method=staticdns=8.8.8.8;4.4.4.4;addresses1=192.168.1.20;24;192.168.1.1;or it may be like this,some initial text[ipv6]method=auto[ipv4]method=staticdns=8.8.8.8;4.4.4.4;addresses1=192.168.1.20;24;192.168.1.1;Now, i want to change after [ipv4] pattern, so that after editing my file should looks like thissome initial text[ipv6]method=auto[ipv4]method=staticdns=8.8.8.8;4.4.4.4;addresses1=192.168.1.20;24;192.168.1.1;