Question

I have a text file. In case there are more than one consecutive line that starts with @, I want to delete all these lines, except of the last occurrence of of a line with @.

For example, lets say I have input file:

abc

@abc

@def

333

@asd

@poi

@789

The output should be:

abc

@def

333

@789

Answer 1

I saw awk tag. so I add an awk one-liner, which could sovle your problem: (see test below)

kent$  cat a.txt
abc
@abc
@def
333
@asd
@poi
@789

kent$  awk 'BEGIN{FS=""}
        {if(c==$1){l=$0;next;} if(c) print l;c=$1;l=$0;} 
        END{print }' a.txt 
abc
@def
333
@789