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Issue when doing a loop

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# 1  
Issue when doing a loop


I just have started learning shell scripting (sh). Why do i only get the date?

while read dt
   echo "Date : ${dt}
   sed -n '/${dt}/,/${dt}/p' file1.log | grep -w ERROR
done < date1.dat

INPUT - date1.dat
2019-04-05 04:58:25
2019-04-05 04:58:26
2019-04-05 05:00:56
2019-04-05 05:08:26
2019-04-05 05:14:08
2019-04-05 05:21:26
2019-04-05 05:31:08

Desired Output
Date : 2019-04-05 04:58:25
2019-04-05 04:58:25,696 [Timer-7] ERROR :  421 Exceeded allowable connection time, disconnecting.

Actual Output
Date : 22019-04-05 04:58:25
Date : 22019-04-05 04:58:26
Date : 22019-04-05 05:00:56
Date : 22019-04-05 05:08:26
Date : 22019-04-05 05:14:08
Date : 22019-04-05 05:21:26
Date : 22019-04-05 05:31:08

Moderator's Comments:
Mod Comment
Please wrap all code, file, input & output/errors in CODE tags
It makes it easier to read and preserves spacing for indenting code or fixed-width data

Last edited by rbatte1; 1 Week Ago at 07:09 AM..
# 2  
The sed does not find anything.
Your mistake is the 'ticks' around $dt, but the shell only expands $dt within "quotes".
Further, a /x/,/x/ range is always one line, so you can simply address it with one /x/.
Further, consider searching only at the beginning of the lines, by means of /^x/, here /^$dt/ or /^${dt}/
Further, you can save the invocation of grep.
sed -n "/ERROR/!d; /^$dt/p" file1.log

sed "/ERROR/!d; /^$dt/!d" file1.log

Note: in bash you need to turn off history substitution with comand set +H.
This User Gave Thanks to MadeInGermany For This Post:
# 3  
Thank you MadeInGermany.
Do i always need to turn off history substitution?
# 4  
Only in an interactive bash shell (i.e. the command line), an exclamation mark followed by an alphanumeric character does history substitution.
For example
echo "!1"

prints line 1 from the command history.
Fortunately a bash script never does history substitution; a set +H work-around is not needed there.
This User Gave Thanks to MadeInGermany For This Post:
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