Linux User Creation

System » User

System » User » Homeless

---

cat << EXE | sudo bash
SYSTEM_SYS_USERS='activemq artemis hadoop spark keycloak minikube minio wildfly'
for SYS_USER in \${SYSTEM_SYS_USERS};do
  if ! id -g \${SYS_USER} &>/dev/null;then addgroup --quiet --system \${SYS_USER};fi
  if ! id -u \${SYS_USER} &>/dev/null;then
    adduser --quiet --system --ingroup \${SYS_USER} --home /nonexistent --shell /usr/sbin/nologin --disabled-password \${SYS_USER}
  fi
done

echo && cat /etc/passwd|awk -F : '\$3 >= 120 && \$3 < 900 {printf("%-6s » %s\n", \$3, \$1)}'|sort -h
echo && cat /etc/group |awk -F : '\$3 >= 120 && \$3 < 900 {printf("%-6s » %s\n", \$3, \$1)}'|sort -h && echo
EXE

System » User » Resident

---

cat << EXE | sudo bash
mkdir -p /home/system/
SYSTEM_SYS_USERS='activemq artemis hadoop spark keycloak minikube minio wildfly'
for SYS_USER in \${SYSTEM_SYS_USERS};do
  if ! id -g \${SYS_USER} &>/dev/null;then addgroup --quiet --system \${SYS_USER};fi
  if ! id -u \${SYS_USER} &>/dev/null;then
    adduser --quiet --system --ingroup \${SYS_USER} --home /home/system/\${SYS_USER} --shell /bin/bash --disabled-password \${SYS_USER}
    chage -m 99999 -M 99999 -E -1 -I -1  \${SYS_USER}

    mkdir /home/system/\${SYS_USER}/.ssh
    touch /home/system/\${SYS_USER}/.ssh/config
    touch /home/system/\${SYS_USER}/.ssh/authorized_keys

    chown -R \${SYS_USER}:\${SYS_USER} /home/system/\${SYS_USER}/
    chmod 600 /home/system/\${SYS_USER}/.ssh/authorized_keys
    chmod 600 /home/system/\${SYS_USER}/.ssh/config
    chmod 700 /home/system/\${SYS_USER}/.ssh
  fi
done

echo && ls -alh /home/system/*/.ssh/*
echo && cat /etc/passwd|awk -F : '\$3 >= 120 && \$3 < 900 {printf("%-6s » %s\n", \$3, \$1)}'|sort -h
echo && cat /etc/group |awk -F : '\$3 >= 120 && \$3 < 900 {printf("%-6s » %s\n", \$3, \$1)}'|sort -h && echo
EXE

DevOps » User

DevOps » User » Resident

---

cat << EXE | sudo bash
mkdir -p /home/devops/
DEVOPS_EXT_USERS='argo.cd drone.ci tool.tech raiyan.shahed shahed.hossain'
for EXT_USER in \${DEVOPS_EXT_USERS};do
  if ! id -u \${EXT_USER} &>/dev/null;then
    useradd --create-home --home-dir /home/devops/\${EXT_USER} --shell /bin/bash \${EXT_USER}
    chage -m 99999 -M 99999 -E -1 -I -1  \${EXT_USER}

    mkdir /home/devops/\${EXT_USER}/.ssh
    touch /home/devops/\${EXT_USER}/.ssh/config
    touch /home/devops/\${EXT_USER}/.ssh/authorized_keys

    chown -R \${EXT_USER}:\${EXT_USER} /home/devops/\${EXT_USER}/
    chmod 600 /home/devops/\${EXT_USER}/.ssh/authorized_keys
    chmod 600 /home/devops/\${EXT_USER}/.ssh/config
    chmod 700 /home/devops/\${EXT_USER}/.ssh
  fi
done

echo && ls -alh /home/devops/*/.ssh/*
echo && cat /etc/passwd|awk -F : '\$3 >= 1000 && \$3 < 65500 {printf("%-6s » %s\n", \$3, \$1)}'|sort -h
echo && cat /etc/group |awk -F : '\$3 >= 1000 && \$3 < 65500 {printf("%-6s » %s\n", \$3, \$1)}'|sort -h && echo
EXE

DevOps » User » EdDSA Key

---

cat <<'EXT'| sudo bash
DEVOPS_EXT_USERS='argo.cd drone.ci tool.tech raiyan.shahed shahed.hossain'
for EXT_USER in ${DEVOPS_EXT_USERS};do
    if id -u ${EXT_USER} &>/dev/null;then
        cat <<'EXE'| sudo -i -u ${EXT_USER} bash
if [ ! -e "${HOME}/.ssh/id_ed25519" ] && [ ! -e "${HOME}/.ssh/id_ed25519.pub" ];then
    ssh-keygen -t ed25519 -C "${USER}@shahed.biz" -N "" -q  -f ${HOME}/.ssh/id_ed25519
fi
cat ${HOME}/.ssh/id_ed25519.pub
EXE
    fi
done
EXT

DevOps » User » Delete

---

cat << EXE | sudo bash
DEVOPS_EXT_USERS='ibrahim.sardar abdul.hakim shalina.begum'
for EXT_USER in \${DEVOPS_EXT_USERS};do
  if id -u \${EXT_USER} &>/dev/null;then
    userdel \${EXT_USER}
    rm -r /home/devops/\${EXT_USER}
  fi
done

echo && ls -alh /home/devops/
echo && cat /etc/passwd|awk -F : '\$3 >= 1000 && \$3 < 65500 {printf("%-6s » %s\n", \$3, \$1)}'|sort -h
echo && cat /etc/group |awk -F : '\$3 >= 1000 && \$3 < 65500 {printf("%-6s » %s\n", \$3, \$1)}'|sort -h && echo
EXE

User » Home » Change

cat <<'EXE'| sudo bash rsync -a /home/artemis /home/system/ usermod -d /home/system/artemis artemis chown artemis:artemis -R /home/system/artemis rm -rf /home/artemis EXE	cat <<'EXE'| sudo bash rsync -a /home/minikube /home/system/ usermod -d /home/system/minikube minikube chown minikube:minikube -R /home/system/minikube rm -rf /home/minikube EXE	cat <<'EXE'| sudo bash rsync -a /home/minio /home/system/ usermod -d /home/system/minio minio chown minio:minio -R /home/system/minio rm -rf /home/minio EXE
cat <<'EXE'| sudo bash rsync -a /home/hadoop /home/system/ usermod -d /home/system/hadoop hadoop chown hadoop:hadoop -R /home/system/hadoop rm -rf /home/hadoop EXE	cat <<'EXE'| sudo bash rsync -a /home/spark /home/system/ usermod -d /home/system/spark spark chown spark:spark -R /home/system/spark rm -rf /home/spark EXE

User » Name » Change

sudo usermod -l chorke deploy
sudo usermod -d /home/chorke -m chorke
sudo groupmod -n chorke deploy

User » Sudo » Privilege

sudo visudo

# User privilege specification root ALL=(ALL:ALL) ALL academia ALL=(ALL:ALL) ALL # Members of the admin group may gain root privileges %admin ALL=(ALL) ALL academia ALL=(ALL) NOPASSWD: /usr/local/bin/supervisorctl # Allow members of group sudo to execute any command %sudo ALL=(ALL:ALL) ALL academia ALL=(ALL) NOPASSWD: /usr/local/bin/supervisorctl # See sudoers(5) for more information on "@include" directives: @includedir /etc/sudoers.d

User » Prevent » Password

Linux » Create » Password less » User
Create Resident User	Delete Password From User	Prevent Password To Set
sudo useradd -m academia sudo chsh -s /bin/bash academia cat /etc/shadow|grep academia cat /etc/passwd|grep academia	sudo passwd -d academia cat /etc/shadow|grep academia cat /etc/passwd|grep academia cat /etc/group |grep academia	sudo passwd -l academia cat /etc/shadow|grep academia cat /etc/passwd|grep academia cat /etc/group |grep academia

User » Immutable » Authorization » Key

Linux » Immutable » authorized_keys
sudo chattr +i /home/academia/.ssh/authorized_keys #Immutable sudo chattr -i /home/academia/.ssh/authorized_keys # Mutable

Playground

lxc image list images:ubuntu/noble/desktop lxc launch --vm images:ffa5fc9dfb84 cloudflare lxc launch --vm images:ubuntu/noble/desktop cloudflare	lxc list status=running name=cloudflare --format=json |jq -r '.[].state.network.[].addresses' lxc list status=running name=cloudflare --format=yaml |yq -r '.[].state.network.[].addresses' lxc info cloudflare|yq '.Resources.["Network usage"][]["IP addresses"].inet'
ls -lah /usr/local/etc/cloudflared/ ls -lah /etc/cloudflared/ ls -lah ~/.cloudflared/	lxc snapshot cloudflare argo:24.04 lxc publish cloudflare/argo:24.04 --alias cloudflare/argo:24.04 lxc restore cloudflare argo:24.04
apt list --installed|grep linux-image	systemd-analyze blame	dpkg -l | grep "gnome-shell-extension"
systemctl list-dependencies graphical.target cat /proc/acpi/wakeup	sudo apt list --installed|grep desktop-icons sudo dpkg-query -l|grep desktop-icons	sudo apt install gnome-shell-extension-manager apt info gnome-shell-extension-manager -a
cat <<-'EXE'|sudo bash umount /var/snap/firefox/common/host-hunspell snap remove firefox EXE	cat <<-'EXE'|sudo bash snap disable remmina snap remove --purge remmina EXE	systemctl list-dependencies --type=service --state=running systemctl list-dependencies --type=service --state=active systemctl list-dependencies docker.service systemctl list-dependencies --all
cat /etc/passwd cat /etc/group	cat /etc/passwd|\ awk -F : '$3 >= 1000 {printf("%-6s » %s\n", $3, $1)}'|sort -h	useradd -m -d /home/chorke -s /bin/bash chorke useradd -m -d /home/chorke -s /bin/bash chorke
adduser --quiet --system --ingroup chorke --no-create-home --shell /usr/sbin/nologin --disabled-password chorke adduser --quiet --system --ingroup chorke --home /nonexistent --shell /usr/sbin/nologin --disabled-password chorke		chsh -s /bin/bash chorke chsh -s /usr/sbin/nologin chorke

References

Linux » AWK » Pad a field with spaces Linux » Add a user without password Linux » Get users with UID >= 1000 Linux » Add User
Ubuntu/Raspberry Pi Ubuntu Upgrade ActiveMQ Minikube Keycloak Hadoop Jenkins WildFly Spark MinIO
Alpine/Morefine Ruby on Rails TensorFlow Homebrew Linuxbrew PyEnv TMux 7Zip Zip Tar	Linux » POSIX » Shell » Environment Variables Linux » Kernel » Microsoft Surface Devices ArchLinux » Network Manager Dispatcher Linux » Disk Encryption Slow Down Ubuntu » 24.04 » Sound Controller SSH Connection Hang Forever Linux » Security » Jail Shell ArchLinux » Installation CIDR UFW	Linux Service Creation Bash/Port/Forward Linux Mount Drive YouTube/Channel Bash/Network Bash/RAM Bash/CPU Bash/Port Bash Port