Question

How do I change a portion of a line after a regexp?

I have a file where I need to modify the line (on the fly) with name = in it but only the one that comes after line with cluster { in it. The file is like this:

cluster {
  name = "Some _ Name"
  owner = "Cavendish Laboratory"
  .....
  .....
}
module {
    name = "core_metrics"
}
service {
    name = "ssh_check"
}
......
......

I can perform this two task separately, like:

sed -n '/cluster\ {/{n;p;}'               # next line after cluster
sed -ic "/name\ =\ /{s:OLD:NEW:g}"        # replace OLD with NEW on the fly

But how do I combine that two to get the end result like: ?

cluster {
  name = "Worker Nodes"
  owner = "Cavendish Laboratory"
  .....
  .....
}

How do I do that? Cheers!

Answer 1

This might work for you:

old="Some _ Name" new="Worker Nodes"

sed '/cluster {/,/}/s/name = "'"$old"'"/name = "'"$new"'"/' file
cluster {
  name = "Worker Nodes"
  owner = "Cavendish Laboratory"
  .....
  .....
}
module {
    name = "core_metrics"
}
    service {
    name = "ssh_check"
}
......
......

• Focus on lines between cluster { and }. /cluster {/,/}/
• Substitute new for old s/name = "'"$old"'"/name = "'"$new"'"/