Creating a User Account with Custom Settings in Linux

This article explains how to create a user account with various custom settings in Linux using a Bash script. The script prompts the user for input, checks for conditions, and executes the necessary commands. Below is the script with explanations for each command.

1. Check for Root User:

   if [[ $(id -u) -ne 0 ]]; then 
     echo "run this script as root user"
     exit 1
   fi        

This checks if the script is being run by the root user (id -u returns the user ID, and 0 is the root user ID). If not, it prints a message and exits.

1. Prompt for Username:

   while [[ -z $username ]]; do 
     read -p "username= " username
   done        

This loop continues to prompt the user for a username until a non-empty value is provided.

1. Prompt for User Alias:

   read -p "user alias= " alias
   if [[ ! -z $alias ]]; then
      alias="-c '$alias'"
   fi        

This prompts the user for an alias and adds it to the user creation command if provided.

1. Prompt for Expiry Date:

   read -p "expiry date= " expirydate
   if [[ ! -z $expirydate ]]; then
     expirydate="-e $expirydate"
   fi        

This prompts the user for an account expiry date and includes it in the command if provided.

1. Prompt for Password Inactive Days:

   read -p "password inactive days= " pwexpiry
   if [[ ! -z $pwexpiry ]]; then
     pwexpiry="-f $pwexpiry"
   fi        

This prompts the user for the number of days after the password expires before the account is disabled.

1. Prompt for Primary Group:

   read -p "primary group= " pgroup
   if [[ -z $pgroup ]]; then
     pgroup=$username  
   fi

   if [[ $(grep -c $pgroup /etc/group) -eq 0 ]]; then
     groupadd $pgroup
   fi        

This checks if the primary group exists, creates it if not, and sets it for the user. If no primary group is provided, it defaults to the username.

1. Prompt for Secondary Group:

   read -p "secondary group= " sgroup
   if [[ ! -z $sgroup ]]; then
     if [[ $(grep -c $sgroup /etc/group) -eq 0 ]]; then
       groupadd $sgroup
     fi  
     sgroup="-G $sgroup"
   fi        

This checks if the secondary group exists, creates it if not, and includes it in the user creation command if provided.

1. Prompt for Home Directory:

   read -p "home dir= " hdir
   if [[ -z $hdir ]]; then  
     hdir="/home/$username"
   fi
   mkdir $hdir        

This prompts for the home directory, defaults to /home/username if not provided, and creates it.

1. Prompt for Default Shell:

   read -p "default shell= " dshell
   if [[ ! -z $dshell ]]; then  
     dshell="-s $dshell"
   fi        

This prompts for the default shell and includes it in the user creation command if provided.

1. Create the User:cmd="useradd $alias $expirydate $pwexpiry -g $pgroup $sgroup -d $hdir $dshell $username"eval $cmdThis constructs and executes the useradd command with all the provided options.
2. Set Ownership and Permissions:bash chown $username:$pgroup $hdirchmod 755 $hdirThis sets the ownership and permissions for the home directory.