how to use sed to replace a row by regex and modify the original file

Question

I have a nginx config file like this:

server {
    listen       80;
    server_name  localhost;

    location /api/test {
        proxy_connect_timeout 3000;
        proxy_send_timeout 3000;
        proxy_read_timeout 3000;
        send_timeout 3000;
        client_max_body_size 10M;
        client_body_buffer_size 100M;
        proxy_pass http://demo.com/;
    }

    location /api/demo {
        proxy_connect_timeout 3000;
        proxy_send_timeout 3000;
        proxy_read_timeout 3000;
        send_timeout 3000;
        client_max_body_size 10M;
        client_body_buffer_size 100M;
        proxy_pass http://demo2.com/;
    }
}

how I want to using the url1 to replace the first proxy_pass and url2 to replace the second proxy_pass in shell, this is my shell script looks like:

#!/usr/bin/env bash

set -u

set -e

set -x

echo "please input url1:"

read URL1

echo "$URL1"

echo "plase input url2:"

read URL2

echo "$URL2"


sed -E "12s/.*proxy\_pass.*/proxy\_pass:$URL1/" nginx.conf

sed -E "22s/.*proxy\_pass.*/proxy\_pass:$URL2/" nginx.conf

now I am facing a problem that the sed did not modify the original file, and only output the url in terminal, what should I do to make it modify the original config file? what I want like this (input www.google.com; and www.facebook.com;):

server {
    listen       80;
    server_name  localhost;

    location /api/test {
        proxy_connect_timeout 3000;
        proxy_send_timeout 3000;
        proxy_read_timeout 3000;
        send_timeout 3000;
        client_max_body_size 10M;
        client_body_buffer_size 100M;
        proxy_pass www.google.com;
    }

    location /api/demo {
        proxy_connect_timeout 3000;
        proxy_send_timeout 3000;
        proxy_read_timeout 3000;
        send_timeout 3000;
        client_max_body_size 10M;
        client_body_buffer_size 100M;
        proxy_pass www.facebook.com;
    }
}

Answer 1

To make sed modify the original file, you need -i. Also, please don't force your users to manually enter things. That just makes your script harder to use: you cannot re-run easily, you cannot automate, and it is very easy to make a mistake. Instead, make the script read the URLs from the command line:

#!/usr/bin/env bash
set -u
set -e
set -x


sed -i -e "12s/.*proxy_pass.*/proxy_pass:$1;/" \
       -e "22s/.*proxy_pass.*/proxy_pass:$2;/" nginx.conf

You should probably make a backup though, and you want to keep the alignment of the data, and you don't have proxy_pass: in the file, you have proxy_pass , which looks like the right format, so try something like this:

#!/usr/bin/env bash
set -u
set -e
set -x

timestamp=$(date +%s.%N)

sed -Ei."$timestamp".bak -e "12s/(.*proxy_pass ).*/\1$1;/" \
        -e "22s/(proxy_pass ).*/\1$2;/" nginx.conf

You then run this with the IPs as arguments:

$ foo.sh 1.2.3.4 5.6.7.8
++ date +%s.%N
+ timestamp=1663148866.892161961
+ sed -Ei.1663148866.892161961.bak -e '12s/(.*proxy_pass ).*/\11.2.3.4/' -e '22s/(proxy_pass ).*/\15.6.7.8;/' nginx.conf

That will create a file with a name like nginx.conf.1663148416.987587536.bak with the original nginx.conf file, and make the changes in nginx.conf.