Exclude a string using grep -v-CodePudding

I have a requirement to exclude a selected string. I am trying to use 'grep -v' option.

Input:

AM2RGHK

AM2RGHK-JO

AM2RGHK-FN

Output should be:

AM2RGHK-JO

AM2RGHK-FN

From the input list, If I want to exclude only first line, I am using "grep -v AM2RGHK" But I am not getting any output. grep -v excludes all the strings in the same sequence. Any clue?

CodePudding user response：

Think about what you have control over, in this case you can compare against the string in question but instead of just the string we can add a pad character on each end and look for that.

#!/bin/bash
read_file="/tmp/list.txt"
exclude="AM2RGHK"
while IFS= read -r line ;do
   if ! [[ "Z${line}Z" = "Z${exclude}Z" ]] ;then
      echo "$line"
   fi
done < "${read_file}"

This case we are saying if ZAM2RGHKZ != current then print it, the comparison would be as follows:

ZAM2RGHKZ  = ZAM2RGHKZ  do nothing
ZAM2RGHKZ != ZAM2RGHK-JOZ print because they don't match
ZAM2RGHKZ != ZAM2RGHK-FNZ print because they don't match

Hence the output becomes:

AM2RGHK-JO
AM2RGHK-FN

Note: there are more succinct ways to do this but this is a good way as well.

CodePudding user response：

grep -v '^AM2RGHK$' input.txt

input.txt:

AM2RGHK
AM2RGHK-JO
AM2RGHK-FN

standard output:

AM2RGHK-JO
AM2RGHK-FN