How can I use sed\awk to look for certain lines within a file, and then match all subsequent lines that match a different pattern?

Question

I have found a similar topic but could not figure out how to implement it for my own use:

grab multiple lines after a matching target line

Here's the issue:

I'm trying to implement it on a project of my own but can't seem to make it work. I am using Linux, can someone break it down?

Basically what I'm trying to do is go through a log bundle and capture specific lines along with their stack\details. Here's an example:

2020-01-20T05:58:19.119Z verbose vpxa[6E21B70] [Originator@6876 sub=PropertyProvider opID=k5cokp1a-928316-auto-jwal-h5:70047736-92-01-84] [CommitChangesAndNotify] Updating cached values
2020-01-20T05:58:19.119Z info vpxa[6E21B70] [Originator@6876 sub=Default opID=k5cokp1a-928316-auto-jwal-h5:70047736-92-01-84] [VpxLRO] -- ERROR task-107599 -- **vm-1178** -- vim.VirtualMachine.reconfigure: vmodl.fault.InvalidArgument:
--> Result:
--> (vmodl.fault.InvalidArgument) {
-->    faultCause = (vmodl.MethodFault) null,
-->    faultMessage = (vmodl.LocalizableMessage) [
-->       (vmodl.LocalizableMessage) {
-->          key = "msg.disk.extendFailure",
-->          arg = (vmodl.KeyAnyValue) [
-->             (vmodl.KeyAnyValue) {

I'll want to capture every line that contains "vm-1178" and all subsequent lines that start with "-->" until the pattern changes, then start looking for vm-1178 until the next time this occurs, etc.

Hope it makes sense. Thanks!

Answer 1

Try this,

awk '!/^-->/{p=0} /vm-1178/{p=1} p'

• !/^-->/{p=0}: Set var p (like print) to 0 whenever line not begins with -->.
• /vm-1178/{p=1}: Set var p = 1 whenever line matches /vm-1178/.
• p: Print the line whenever p is true (here=1)

Answer 2

You could use awk for that purpose:

awk 'index($0,"vm-1178")>0 {in_pat=1; print; next} \
in_pat == 1 && $0 ~ /^-->/ {print; next} \
{in_pat=0}' logfile.txt

It contains three rules:

• The first rule will look for lines containing the pattern and print these, as well as setting an internal flag in_pat to 1.
• The second rule states that all subsequent lines starting with --> will be printed as well.
• The third rule is used to reset that flag upon the very first line not containing the pattern or not starting with a -->, so that nothing is printed until the pattern is found again.

Note that in the first rule, the index function is used rather than a RegExp match. This is so that you can also look for patterns containing characters that have a special meaning in regular expressions.

Answer 3

Using perl, this would work:

 perl -ne ' { $t=0 if ( !/^-->/ ); $t=1 if(/vm-1178/); print if($t); }' <filename>