use of variables in awk to search for pattern from a file

[Jean John]

Hi,

I need to extract all the content between two strings stored in two variables "startstring" and "endstring"

startstring=Hello
enstring=world
 #not working
awk '/$startstring/, $NF ~ /$endstring/ ' errors.log > /tmp/errorlogs/errorfile2      

The above code is not working with variables. It works when actual string values are used as pattern.

#working
awk '/hello/, $NF ~ /world/ ' errors.log > /tmp/errorlogs/errorfile2

Can someone help me to use these two variables in awk.

Thanks.

Regards,
Jean

[Tim Holloway]

Unix shells have several different "quote" characters, and each one has a special meaning. For example, the backtick "quotes" cause the quoted expression to be run as a shell command.

Unfortunately, the single-quote "quotes" mean "don't expand shell variables". Use the double-quote "quotes" instead. Or, in other words:

awk "/$startstring/, $NF ~ /$endstring/ " errors.log > /tmp/errorlogs/errorfile2     

It's a convention that environment variables should be named all in uppercase, BTW. However, that's just a convention, so using lower-case names won't actually hurt anything.