Fix "sudo: command not found"

Understanding the Error

sudo is not installed or not in PATH.

Fix 1: Install sudo (as root)

# For Debian/Ubuntu (as root)
apt update && apt install sudo -y

# For CentOS/RHEL (as root)
yum install sudo -y

# For Alpine (as root)
apk add sudo

Fix 2: Add User to sudoers

# As root
usermod -aG sudo username      # Debian/Ubuntu
usermod -aG wheel username     # CentOS/RHEL

# Verify
groups username

Fix 3: Fix PATH Environment

# Temporarily use full path
/usr/bin/sudo command

# Add to ~/.bashrc
export PATH=$PATH:/usr/bin:/usr/sbin
source ~/.bashrc

Fix 4: Run as Root Instead

If sudo not available:

su -
# Enter root password
# Then run commands without sudo

Fix 5: Minimal Docker Containers

Run as root inside container or use USER root in Dockerfile.

Fix 6: Check sudo Exists

which sudo
whereis sudo
find / -name sudo -type f 2>/dev/null

If not found, install from your distribution's package manager.