sed is not working for commenting a line in a file using bash script

Question

I have created a bash script that is used to modify the ulimit of open files in the RHEL server.

so i have reading the lines in the file /etc/security/limits.conf and if the soft/hard limit of the open files are less than 10000 for '*' domain i am commenting the line and adding a new line with soft/hard limit as 10000.

The Script is working as designed but the sed command to comment a line in the script is not working.

Please find the full script below :-

#!/bin/sh
#This script would be called by '' to set ulimit values for open files in unix servers.
#
configfile=/etc/security/limits.conf
help(){
echo "usage: $0 <LimitValue>"
echo -e "where\t--LimitValue= No of files you want all the users to open"
exit 1
}
modifyulimit()
{
grep '*\s*hard\s*nofile\s*' $configfile | while read -r line ; do
        firstChar="$(echo $line |  xargs | cut -c1-1)"
        if [ "$firstChar" != "#" ];then
        hardValue="$(echo  $line | rev | cut -d ' ' -f1 | rev)"
            if [[ "$hardValue" -ge "$1" ]]; then
            echo ""
            else
            sed -i -e 's/$line/#$line/g' $configfile 
            echo "*          hard     nofile         $1" >> $configfile
            fi
        else
            echo ""
        fi
    done

grep '*\s*soft\s*nofile\s*' $configfile | while read -r line ; do
        firstChar="$(echo $line |  xargs | cut -c1-1)"
        if [ "$firstChar" != "#" ];then
        hardValue="$(echo  $line | rev | cut -d ' ' -f1 | rev)"
            if [[ "$hardValue" -ge "$1" ]]; then
            echo ""
            else
            sed -i -e 's/$line/#$line/g' $configfile 
            echo "*          hard     nofile         $1" >> $configfile
            fi
        else
            echo ""
        fi
    done
}
deleteEofTag(){
sed -i "/\b\(End of file\)\b/d" $configfile
}
addEofTag()
{
echo "#################End of file###################" >> $configfile
}
#-------------Execution of the script starts here ----------------------
if [ $# -ne 1 ];
then
help
else
modifyulimit $1
deleteEofTag
addEofTag
fi

The command sed -i -e 's/$line/#$line/g' $configfile when executed from the terminal is working absolutely fine and it is commenting the line but it is not working when i am executing it from the unix shell script.

Answer 1

interpolation does not work in single quote use double quote and try

sed -i -e 's/$line/#$line/g'

sed -i -e "s/$line/#$line/g"