Linux System Administration Guide

📋 Table of Contents

System Update Automation
External Storage Detection
Formatting Storage for Backup
Auto-mounting Configuration

🔄 System Update Automation

Automate system updates using a bash script and cron jobs. This ensures your system stays up-to-date without manual intervention.

Step 1: Create the Update Script

#!/bin/bash
# System Update Automation Script
# Save as: /usr/local/bin/system-update.sh

# Log file location
LOGFILE="/var/log/system-update.log"

# Function to log messages
log_message() {
    echo "$(date '+%Y-%m-%d %H:%M:%S') - $1" | tee -a "$LOGFILE"
}

log_message "Starting system update"

# Detect the distribution
if [ -f /etc/debian_version ]; then
    # Debian/Ubuntu
    log_message "Detected Debian/Ubuntu system"
    apt-get update >> "$LOGFILE" 2>&1
    DEBIAN_FRONTEND=noninteractive apt-get upgrade -y >> "$LOGFILE" 2>&1
    apt-get autoremove -y >> "$LOGFILE" 2>&1
    apt-get autoclean >> "$LOGFILE" 2>&1
    
elif [ -f /etc/redhat-release ]; then
    # RHEL/CentOS/Fedora
    log_message "Detected RHEL/CentOS/Fedora system"
    yum update -y >> "$LOGFILE" 2>&1 || dnf upgrade -y >> "$LOGFILE" 2>&1
    
elif [ -f /etc/arch-release ]; then
    # Arch Linux
    log_message "Detected Arch Linux system"
    pacman -Syu --noconfirm >> "$LOGFILE" 2>&1
    
else
    log_message "Unknown distribution"
    exit 1
fi

log_message "System update completed"

Step 2: Make the Script Executable

Command:

sudo nano /usr/local/bin/system-update.sh

sudo chmod +x /usr/local/bin/system-update.sh

Step 3: Set Up Cron Job

Edit crontab:

sudo crontab -e

Add one of these schedules:

                        # Run every day at 2 AM
0 2 * * * /usr/local/bin/system-update.sh

# Run every Sunday at 3 AM
0 3 * * 0 /usr/local/bin/system-update.sh

# Run every day at 2 AM and reboot if needed (Debian/Ubuntu)
0 2 * * * /usr/local/bin/system-update.sh && [ -f /var/run/reboot-required ] && /sbin/reboot

ℹ️ Important Notes:

The script runs as root (via sudo crontab)
Updates are logged to /var/log/system-update.log
Test manually first: sudo /usr/local/bin/system-update.sh

💾 External Storage Detection

Learn how to detect and identify external storage devices like SD cards connected to your Linux system.

Quick Check - List All Block Devices

lsblk

Example Output:

NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
loop0         7:0    0     2G  0 loop 
sda           8:0    1 116.6G  0 disk 
├─sda1        8:1    1   512M  0 part /boot/firmware
└─sda2        8:2    1 116.1G  0 part /
mmcblk0     179:0    0  29.7G  0 disk 
├─mmcblk0p1 179:1    0   255M  0 part 
└─mmcblk0p2 179:2    0  29.5G  0 part

Other Detection Methods

Check kernel messages:

dmesg | tail -20
dmesg | grep -i mmc

List disk devices:

sudo fdisk -l

Check USB devices (if using card reader):

lsusb

Check mounted filesystems:

df -h

🔍 Device Naming:

mmcblk0 - SD card (built-in reader)
sdb, sdc - USB card reader
mmcblk0p1, sdb1 - Partitions on the device

🔧 Formatting Storage for Backup

Format an external storage device (SD card) for use as a Linux backup drive.

Step 1: Unmount Existing Partitions

sudo umount /dev/mmcblk0p1
sudo umount /dev/mmcblk0p2

Step 2: Create New Partition Table

sudo fdisk /dev/mmcblk0

Inside fdisk:

Type o (create new DOS partition table) and press Enter
Type n (new partition) and press Enter
Press Enter (primary partition)
Press Enter (partition number 1)
Press Enter (first sector, default)
Press Enter (last sector, use full disk)
Type w (write changes) and press Enter

Step 3: Format the Partition

For ext4 (Linux-only, recommended for backups):

sudo mkfs.ext4 -L BACKUP /dev/mmcblk0p1

For exFAT (Windows/Mac compatibility):

sudo apt-get install exfat-fuse exfat-utils
sudo mkfs.exfat -n BACKUP /dev/mmcblk0p1

Step 4: Mount the Drive

sudo mkdir -p /mnt/backup
sudo mount /dev/mmcblk0p1 /mnt/backup

Step 5: Set Proper Permissions (ext4 only)

sudo chown -R $USER:$USER /mnt/backup

⚠️ Note: If using exFAT, you cannot use chown. Instead, mount with permissions:

sudo mount -o uid=$(id -u),gid=$(id -g),umask=0022 /dev/mmcblk0p1 /mnt/backup

Step 6: Verify

df -h | grep backup
lsblk
touch /mnt/backup/test.txt
ls -l /mnt/backup/

⚙️ Auto-mounting Configuration

Configure your backup drive to automatically mount on system boot using /etc/fstab.

Step 1: Get the PARTUUID

sudo blkid /dev/mmcblk0p1

Example Output:

                        /dev/mmcblk0p1: LABEL="BACKUP" UUID="a1b2c3d4-..." TYPE="ext4" PARTUUID="12345678-01"
                    

Step 2: Edit /etc/fstab

sudo nano /etc/fstab

Step 3: Add Entry to fstab

Using device name (simpler):

/dev/mmcblk0p1 /mnt/backup ext4 defaults 0 2

Using PARTUUID (more reliable):

PARTUUID=12345678-01 /mnt/backup ext4 defaults 0 2

Example complete /etc/fstab:

proc            /proc           proc    defaults          0       0
PARTUUID=4c5e577c-01  /boot/firmware  vfat    defaults          0       2
PARTUUID=4c5e577c-02  /               ext4    defaults,noatime  0       1
PARTUUID=12345678-01  /mnt/backup     ext4    defaults          0       2

Step 4: Test the Configuration

sudo umount /mnt/backup
sudo mount -a
df -h | grep backup

✅ Success! Your backup drive will now automatically mount on every boot at /mnt/backup.

⚠️ Common Issues:

Operation not permitted when using chown - You're using exFAT. Use mount options instead or reformat to ext4.
Device not found - Check device name with lsblk
Wrong filesystem type - Verify with sudo blkid

🎯 Quick Reference Commands

Check available storage:

lsblk
df -h
sudo fdisk -l

Mount/Unmount:

sudo mount /dev/mmcblk0p1 /mnt/backup
sudo umount /mnt/backup

Format drives:

sudo mkfs.ext4 -L LABEL /dev/mmcblk0p1
sudo mkfs.exfat -n LABEL /dev/mmcblk0p1

Check device info:

sudo blkid
sudo parted -l