Sstrhsrtj

What is wrong with the sed command on deleting the line which matches the input data?

InputData.txt

123,

1234,

1453,

Datatodelete.txt

1234,hellofirstline

123,hellosecondline

14676,hellothirdline

1453,hellofourthline

expected output in the Datatodelete.txt

14676,hellothirdline

Script:

echo "the script starts now"

while read EachLine

do

  echo $EachLine

  sed "/$EachLine/d" < /home/Datatodelete.txt >/home/dummy

done < /home/InputData.txt

Your sed command doesn't work because during the loop, each time it reads a line, it deletes that line (and only that line) from the full input file, outputting it to /home/dummy. This means that the output file gets overwritten each time. So the first iteration of the loop removes the line starting with 123, but then the second iteration uses the original full file which still includes this line.

Try grep instead:

grep -vFf /home/InputData.txt /home/Datatodelete.txt > /home/dummy

From man grep:

   -F, --fixed-strings

          Interpret PATTERN as a  list  of  fixed  strings,  separated  by

          newlines,  any  of  which is to be matched.  (-F is specified by

          POSIX.)



   -f FILE, --file=FILE

          Obtain  patterns  from  FILE,  one  per  line.   The  empty file

          contains zero patterns, and therefore matches nothing.   (-f  is

          specified by POSIX.)

   -v, --invert-match

          Invert the sense of matching, to select non-matching lines.  (-v

          is specified by POSIX.)

An awk version:

awk -F, 'FNR==NR{a[$1];next} !($1 in a)' InputData.txt Datatodelete.txt

First, you don't want while read in there anywhere - sed will read your file. Next, you need to make sure that you handle greedy matches - sed will pull in as much as it can. So

    echo 1234 | sed -n '/123/p' 

1234

See? It prints it.

So you need, based on what you've shown, something like this:

    </home/InputData.txt 

        sed -n '/1234/s//& hellofirstline/p;

        /123[^4]/s//& hellosecondline/p;

        /14676/s//& hellothirdline/p; 

        /1453/s//& hellofourthline/p' >/home/dummy

If your sed script is in a file:

    </home/InputData.txt 

        sed -nf ./delete.sed >/home/dummy