search for pattern and print previous lines?

[ZorbasE]

Hello, im new to the forum and to AWK...

is it pls possible to search for a pattern and print a previous line? I tried to do that by decrementing NR but
it didnt work of course. To be more specific, say that i
find a pattern on line X and if that happens i need to
print or store a field of line X-3 etc.

thank you in advance

Yannis

 

[feherke]

Hi

You can not step back. Must store the data temporary, until you reach the condition line :

awk '/[green][i]condition[/i][/green]/{print p[(NR+1)%3]}{p[(NR+1)%3]=$0}' /input/file

Feherke.

http://rootshell.be/~feherke/

 

[Annihilannic]

Off topic I know, but if you have GNU grep you can use grep -Bn pattern inputfile | grep -v pattern where n is the number of lines of context you want.

Annihilannic.