Reading logs with the word 'ERROR' between 2 dates

Question

The logs are in the format:

2018-06-25 00:00:20,073 DEBUG SAMPLE TEXT CONTENT
2018-06-26 00:00:20,073 ERROR SAMPLE TEXT CONTENT
2018-06-26 17:37:20,073 ERROR SAMPLE TEXT CONTENT
2018-06-26 19:00:20,073 DEBUG SAMPLE TEXT CONTENT
2018-06-27 00:00:20,073 DEBUG SAMPLE TEXT CONTENT
2018-06-28 00:00:20,073 ERROR SAMPLE TEXT CONTENT
2018-06-29 00:00:20,073 ERROR SAMPLE TEXT CONTENT
2018-06-30 00:00:20,073 DEBUG SAMPLE TEXT CONTENT
2018-07-01 11:00:20,073 ERROR SAMPLE TEXT CONTENT
2018-07-02 02:00:20,073 DEBUG SAMPLE TEXT CONTENT
2018-07-02 00:00:20,073 ERROR SAMPLE TEXT CONTENT
2018-07-03 20:00:20,073 ERROR SAMPLE TEXT CONTENT

I want to find and display all the logs between 2 dates (suppose 2018-06-26 to 2018-07-02) which have the word ERROR in it. I am gonna take the dates in dynamically so they will be variables $FROM and $TO.

Any grep, awk or sed implementation will do

EDIT: Both the $TO and $FROM dates should be inclusive and might need to access multiple log files so the logs may not be sorted

Answer 1

awk, using -v option to pass shell variables into awk variables:

$ awk -v from="$FROM" -v to="$TO" 'from <= $1 && $1 <= to && /ERROR/' log.txt
2018-06-26 00:00:20,073 ERROR SAMPLE TEXT CONTENT
2018-06-26 17:37:20,073 ERROR SAMPLE TEXT CONTENT
2018-06-28 00:00:20,073 ERROR SAMPLE TEXT CONTENT
2018-06-29 00:00:20,073 ERROR SAMPLE TEXT CONTENT
2018-07-01 11:00:20,073 ERROR SAMPLE TEXT CONTENT
2018-07-02 00:00:20,073 ERROR SAMPLE TEXT CONTENT

Answer 2

Using AWK:

awk '/'$FROM'/,/'$TO'/ {print $0}' log.txt | grep ERROR

Using sed:

sed -n '/'$FROM'/,/'$TO'/p' log.txt | grep ERROR

Answer 3

Simple yet effective;

egrep '2018-06-26|2018-07-02' log file | grep "ERROR"

Answer 4

Loop the dates (via):

FROM=2018-06-26
TO=2018-07-02
d=$FROM
while [ $d != $TO ]; do 
  grep "^${d}.*ERROR" logfile
  d=$(date -I -d "$d + 1 day")
done