Question

I tried this:

file="myfile"
while read -r line
do
    [[ $line = \#* ]] && continue
    "address=\$line\127.0.0.1"
done < "$file"

This code doesn’t avoid the lines that begin with comments. Even if I don’t have any comments, dnsmasq tells that there are errors.

Its going to be a dnsmasq conf file, and it will read and insert domain names like so: address=\mydomain.com\127.0.0.1.

---

EDIT:1

Input file:

domain1.com
domain2.com
domain3.com
#domain4.com
domain5.com

Output should be:

address=/domain1.com/127.0.0.1
address=/domain2.com/127.0.0.1
address=/domain3.com/127.0.0.1
address=/domain5.com/127.0.0.1

I will drop the script in /etc/dnsmasq.d/ directory so that dnsmaq.conf can process it when dnsmasq is started.

Answer 1

It’s safer to use [[ "$line" = "\#*" ]]

Btw, address="\\${line}\\127.0.0.1"

UPD:

If I’ve understand you right you need to change every uncommented domains to address=\domain\127.0.0.1. It could be done fast and easy with sed, there is no need in bash-program.

$> cat ./text
domain1.com
domain2.com
domain3.com
#domain4.com
domain5.com

$> sed -r -e 's/(^[^#]*$)/address=\/\1\/127.0.0.1/g' ./text2
address=/domain1.com/127.0.0.1
address=/domain2.com/127.0.0.1
address=/domain3.com/127.0.0.1
#domain4.com
address=/domain5.com/127.0.0.1

If you need to remove commented lines, sed can do it too with /matched_line/d

$> sed -r -e 's/(^[^#]*$)/address=\/\1\/127.0.0.1/g; /^#.*$/d' ./text2 
address=/domain1.com/127.0.0.1
address=/domain2.com/127.0.0.1
address=/domain3.com/127.0.0.1
address=/domain5.com/127.0.0.1

UPD2: if you want to do all that stuff inside the bash script, here is your code modification:

file="./text2"
while read -r line; do
    [[ "$line" =~ ^#.*$ ]] && continue
    echo "address=/${line}/127.0.0.1"
done < "$file"

And it’s output:

address=/domain1.com/127.0.0.1
address=/domain2.com/127.0.0.1
address=/domain3.com/127.0.0.1
address=/domain5.com/127.0.0.1