change-host 🤘

While developing, we are always stuck with the tiresome edit of etc/hosts to map the redirecting dev IP to some.url.com. Using this script below, you can do that using a single command using the CLI and save yourself some time. Something like change-host myFavouriteIp.

Step-by-step guide

1. Go to the directory wherever you store your scripts and create a file to whatever name you want the command to be.

    cd ~/workspace/scripts
    vim change-host

2. (For Mac users) Install gsed the mac alternative for sed which actually does the job for find and replace

   brew install gsed

3. Copy and paste this piece of code to the file created which you can also find in this repository itself change-host.sh.

   NOTE: Replace URL inside the script to actually redirect it to the url you want to redirect to. By default it is some.url.com.

   ETC_HOSTS=/etc/hosts
   ipRegex=^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$
   
   ARG=$1
   ALIAS=$2
   
   # Put the URL here to redirect the specified IP. (ex - redir.dev.com)
   URL=some.url.com
   
   # Prepends every uncommented URL
   comment_redir () { sudo gsed -i "/^[^#].*$URL/s/^/# /g" $ETC_HOSTS; }
   
   if [ -n "$(sudo grep -w $ARG $ETC_HOSTS)" ]
       then
       comment_redir
       if [[ $ARG =~ $ipRegex ]]
           then
           echo "$ARG is now $URL"
           sudo gsed -i "s/# $ARG/$ARG/g" $ETC_HOSTS
       else
           echo "Redirecting to IP marked with $ARG"
           sudo gsed -i "/$ARG/{n;s/# //}" $ETC_HOSTS
       fi
   else
       if ! [[ $ARG =~ $ipRegex ]]
           then
           echo "Cannot find any reference to $ARG"
       elif [ -n "$ALIAS" ]
           then
           comment_redir
           sudo printf "\n# $ALIAS\n$ARG $URL" | sudo tee -a $ETC_HOSTS
       else
           comment_redir
           sudo printf "\n$ARG $URL" | sudo tee -a $ETC_HOSTS
       fi
   fi

4. Make this file an executable.

   chmod +x change-host

5. Add the path to the scripts folder in the PATH variable wherever you are exporting it (.bash_profile/.zshrc etc)

   export PATH=$HOME/workspace/scripts:$PATH
   
   source .bash_profile

6. YOU ARE GOOD TO GO 🤘

How to use

Since everyone must be having a different kind of etc/hosts, I have made the script according to how I manage my etc/hosts. Here is how it looks like for me.

Note the comments above the IPs (Me, aliasName, theOne) which would come in handy later.

# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting.  Do not change this entry.
##
127.0.0.1       localhost
255.255.255.255 broadcasthost
::1             localhost
 
# Me
# 10.2.102.54 redir.dev.com
 
# aliasName
# 10.2.148.86 redir.dev.com
 
# theOne
10.2.200.76 redir.dev.com
 
# 10.2.148.83 redir.dev.com
# 10.2.420.69 redir.dev.com

Note I have set my URL to redir.dev.com inside the change-host file

• Using it with an existing IP (would comment every other except the provided one)

  change-host 10.2.102.54

• Using it with an alias (ex- Me, aliasName, theOne etc..)

  change-host aliasName
  

• Adding a new IP without an alias

  change-host 10.10.10.10

• (Recommended) Adding a new IP with an Alias so that it can be used later.

  change-host 10.10.10.10 newRedirect

  Later you can use it like this. change-host newRedirect

Note: This uses sudo internally cause you know how etc/host is. So you would be asked to enter the password.

TODOs

• Add support for removal
• Add support for passing the redirect url inside the CLI.