I've got a longish log file with content such as

Uplink traffic:
Downlink traffic:

I want to parse the log file and remove any line that contains the string "Uplink traffic:" at the beginning of the line, but only if the line following it beginnings with the string "Downlink traffic:" (in other words a grep -v won't work)

put sample of the file and the desired o/p

In cases where successive lines are of the form

Uplink traffic:
Downlink traffic:

I want the "Uplink traffic:" line removed

In cases where successive lines are of the form

Uplink traffic:
Dropped packets: 40
Downlink traffic:

I don't want the "Uplink traffic:" line removed

Something like this :

awk '/Uplink traffic:/ {p=NR;st=$0;q=1;next} /Downlink traffic:/ {print (NR==p+1)?$0:$0;q=0;next} { if(q==1){q=0;print st} print}' file_name.txt

Cheers Panyam.. that worked. No idea how though.. Must have a read of an Awk tutorial and figure it out.

code

nawk '
/Uplink/{getline a;getline b; if (a !~ /^Down/){printf"%s\n%s\n%s\n\n",$0,a,b} else {printf"%s \n\n",a} }
' up

Check the script , I guess it wont give the desired result as "yorkie99" expected.