How do I get all the text between the last two instances of a token in bash? - bash

Question

I’m using bash and running the following command to get all the file text between two tokens (including the tokens themselves):
cat /usr/java/jboss/standalone/log/server.log | sed -n \
'/Starting deployment of "myproject.war"/,/Registering web context: \/myproject/p'
However, sometimes the tokens occur multiple times in the file. How do I adjust the above so that only the text between the last two occurrences of the tokens (including the tokens themselves) will be returned?

Answer 1

How about some tic-tac-toe.
tac /usr/java/jboss/standalone/log/server.log |
awk '/Registering web context: \/myproject/{p=1;++cnt}/Starting deployment of "myproject.war"/{if(cnt==2){print $0;exit};print $0;p=0}p' |
tac

Answer 2

This solution is not efficient, but easier to understand:
file='/usr/java/jboss/standalone/log/server.log'
s1='Starting deployment of "myproject.war"'
s2='Registering web context: \/myproject'
sed -n '/'"$s1"'/,/'"$s2"'/p' "$file" |
tac |
awk '/'"$s1"'/ {print;exit} 1' |
tac
Lets sed report ALL ranges first.
Reverses the result using tac (on OSX, use tail -r).
Using awk, outputs everything up to and including the first occurrence of the first substring, which - in the reversed result - spans the end of the last range to the start of the last range.
Reverses the output from awk to render the last range in correct order.
Note: For consistency with the variable use in the sed command I've spliced a variable reference directly into the awk program, too, which is otherwise poor practice (use -v to pass variables instead).

Answer 3

You can do this in native bash -- no need for awk, tac, or any other external tool.
token1='Starting deployment of "myproject.war"'
token2='Registering web context: /myproject/'
writing=0
while read -r; do
(( ! writing )) && [[ $REPLY = $token1 ]] && {
# start collecting content, into an empty buffer, when we see token1
writing=1 # set flag to store lines we see
collected_content=() # clear the array of lines found so far
}
(( writing )) && {
# when the flag is set, collect content into an array
collected_content+=( "$REPLY" )
}
[[ $REPLY = $token2 ]] && {
# stop collecting content when we see token2
writing=0
}
done <server.log # redirect from the log into the loop
# print all collected lines
printf '%s\n' "${collected_content[#]}"

Answer 4

This awk can work:
awk '/Starting deployment of "myproject.war"/{i=0; s=1; delete a;}
s{a[++i]=$0}
/Registering web context: \/myproject/{s=0}
END {print i; for (k=1; k<=i; k++) print a[k]}' file

Answer 5

With perl:
perl -0xFF -nE '#x = /WWWW Starting deployment of "myproject.war"(.*?)Registering web context: \/myproject/sg; say $x[-1] ' file