Question

I need to replace a string between two lines. For example:

"aaa\nfoo\nfoo\naaa\nfoo\nbbb\nfoo\nbbb" ==> "aaa\nfoo\nfoo\naaa\nright\nbbb\nfoo\nbbb"

I want to use perl like following format but failed:

echo -e "aaa\nfoo\nfoo\naaa\nfoo\nbbb\nfoo\nbbb" | perl -pe "code here"

So is there a good way to deal with it?

Both perl and awk is ok.

Answer 1

Perl:

echo -e "aaa\nfoo\nfoo\naaa\nfoo\nbbb\nfoo\nbbb" | perl -p00e 's/aaa\nfoo\nbbb/aaa\nright\nbbb/'

if you need to match a pattern multiline, you must change the record separator. the flags m and s can be useful too.

see also

perl --help         # -0
perldoc perlvar     # $/
perldoc perlre      # /Modifiers
perl -MO=Deparse -p00e 's/aaa\nfoo\nbbb/aaa\nright\nbbb/'

Awk:

echo -e "aaa\nfoo\nfoo\naaa\nfoo\nbbb\nfoo\nbbb" | awk 'BEGIN{RS=""}{sub(/aaa\nfoo\nbbb/,"aaa\nright\nbbb",$0);print}'