Pass variable from shell script to config file

Question

I have to write a shell script to install multiple services dynamically. I don´t know too much about shell scripting or the unix shell general, so I really need some help. This is my shell file.

#!/bin/bash
# Ask the user for their name
echo What is the name of your domain?
read varname

echo You passed the domain name to your domain $varname successfully

This is my nginx.conf file.

server {
  listen                80;
  server_name           $varname;
  rewrite     ^(.*)     https://$server_name$1 permanent;
}

I want to pass varname to the nginx.conf file to set the server name based on the users input. How can I do this?

Bodo · Accepted Answer · 2020-03-04 09:30:07Z

1

You could create the file nginx.conf from a heredoc.

#!/bin/bash
# Ask the user for their name
echo What is the name of your domain?
read varname

cat > nginx.conf <<EOF
server {
  listen                80;
  server_name           $varname;
  rewrite     ^(.*)     https://\$server_name\$1 permanent;
}
EOF

echo You passed the domain name to your domain $varname successfully

Note: In the rewrite line I escaped the $ characters to get literal $ in the output instead of shell variable expansion.

If I enter foobar, this results in a file nginx.conflike this:

server {
  listen                80;
  server_name           foobar;
  rewrite     ^(.*)     https://$server_name$1 permanent;
}

answered Mar 4, 2020 at 9:30

Bodo

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Comments

RavinderSingh13 · Accepted Answer · 2020-03-04 09:26:35Z

1

Could you please try following. This will change value on line which is starting from space and has server_name's last field to provided value by user.

#!/bin/bash
# Ask the user for their name
echo What is the name of your domain?
read varname

awk -v var="$varname" '/^ +server_name/{$NF=var} 1' nginx.conf > temp && mv temp nginx.conf &&\
echo You passed the domain name to your domain $varname successfully

answered Mar 4, 2020 at 9:26

RavinderSingh13

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Comments

Freddy · Accepted Answer · 2020-03-04 10:09:28Z

1

You can use envsubst for this.

Rename your nginx.conf to nginx.conf.template and change your script to:

#!/bin/bash

read -p "What is the name of your domain? " varname

export varname
envsubst '$varname' < nginx.conf.template > nginx.conf

echo "You passed the domain name to your domain $varname successfully"

answered Mar 4, 2020 at 10:09

Freddy

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