Search file for pattern and grab some lines before pattern

Shell Programming and Scripting
1

I want to search a file for a string and then if the string is found I need the line that the string is on - but also the previous two lines from the file (that the pattern will not be found in)

This is on solaris

Can you help?

2

There is some option for grep itself for this same purpose like grep -An (for getting n lines above the searched pattern) and grep -Bn (for getting n lines below the searched pattern) ... not sure if this is there for solaris ... i think no ...

meanwhile u can try out this solution as well ...

grep -n pattern filename | cut -d":" -f1 | xargs -i expr {} - 2 | xargs -i sed -n '{},/pattern/ p' filename

3

Awk:

NR>3 { delete a[NR-3] }
/find this/ { print a[NR-2]; print a[NR-1]; print }
{ a[NR] = $0 }