create users with keys

create_users.sh

# Usage: 
#    bash create_users.sh users.txt
# each line in users.txt is a username
# 
# Requires:
#   apt install pwgen 


user_exists(){ id $1 &>/dev/null; }

has_pwgen=`which pwgen`
if [ -z $has_pwgen ]
then
    echo "install pwgen firstly: apt install pwgen"
    exit -1
fi

if [ -d keys ]
then
    echo "keys dir exists, you must del it"
    exit -1
fi

mkdir keys
for name in `cat $1`
do
    echo "==========================================================="
    echo "creating user $name ... "
    if user_exists $name
    then
        echo "user $name exists, skip it ...."
        echo ""
        echo ""
        continue
    fi
    adduser --disabled-password --gecos "" $name
    # generate key
    phrase=`pwgen 16 1`
    echo "passphrase: $phrase"
    ssh-keygen -b 2048 -t rsa -N $phrase -f ./keys/id_rsa_$name
    cp ./keys/id_rsa_$name ./keys/id_rsa_$name.copy
    cp ./keys/id_rsa_$name.pub ./keys/id_rsa_$name.pub.copy

    # register key
    mkdir /home/$name/.ssh
    mv ./keys/id_rsa_$name /home/$name/.ssh/id_rsa
    mv ./keys/id_rsa_${name}.pub /home/$name/.ssh/id_rsa.pub
    cat /home/$name/.ssh/id_rsa.pub > /home/$name/.ssh/authorized_keys
    chown -R $name:$name /home/$name/.ssh/
    chmod 700 /home/$name/.ssh
    chmod 600 /home/$name/.ssh/authorized_keys

    echo "$name $phrase" >> keys/passphrase
    echo ""
    echo ""
done