remote-system-maintenance

What this skill does

# Remote System Maintenance

## Purpose

Structured guidance for diagnosing and maintaining remote Linux systems through SSH/tmux sessions, with emphasis on Ubuntu/Debian platforms.

## Applicable Scenarios

- System maintenance tasks
- Disk space recovery
- Package updates
- Health diagnostics
- Cleanup operations on remote servers

## Three-Phase Approach

### Phase 1: Initial Diagnostics

Capture baseline system state:
- Hostname and system identification
- Resource utilization (disk, memory, CPU)
- Process status and load
- Zombie process detection

### Phase 2: System Log Review

Examine system health indicators:
- Recent error messages in system logs
- Journal disk consumption analysis
- Critical service status
- Authentication and security events

### Phase 3: Package Assessment

Identify maintenance opportunities:
- Upgradable packages
- Orphaned configurations
- Unused dependencies
- Package cache size

## Ubuntu/Debian Cleanup Sequence

Execute these seven stages in order:

1. **Package Cache Refresh** - `apt update` to sync package lists
2. **System Upgrades** - `apt upgrade` for security and bug fixes
3. **Orphan Removal** - `apt autoremove` to clean unused dependencies
4. **Cache Purging** - `apt clean` to reclaim package cache space
5. **Journal Pruning** - `journalctl --vacuum-time=7d` to limit log retention
6. **Snap Revision Cleanup** - Remove disabled snap revisions (see below)
7. **Temporary Directory Assessment** - Review `/tmp` and `/var/tmp` for cleanup opportunities

## Snap Revision Cleanup Technique

Snap keeps old revisions by default. To identify and remove:

```bash
# List all disabled snap revisions
snap list --all | awk '/disabled/{print $1, $3}'

# Remove specific revision
snap remove <package-name> --revision=<revision-number>
```

**Important**: Requires explicit removal by revision number, not simple package uninstallation.

## Documentation Requirements

All maintenance sessions must generate structured logs recording:

1. **System Identification**
   - Hostname
   - OS version
   - Kernel information
   - Operator identity

2. **Resource States**
   - Initial disk/memory/CPU usage
   - Final disk/memory/CPU usage
   - Quantified improvements

3. **Actions Taken**
   - Specific commands executed
   - MB/GB freed per category
   - Packages upgraded/removed

4. **Follow-up Recommendations**
   - Remaining issues
   - Future maintenance needs
   - Monitoring suggestions

## Expected Results

Real-world recovery examples:
- **Journal vacuuming**: 300-600 MB
- **Snap revision cleanup**: 500 MB to 2 GB
- **Package cache purging**: 100-500 MB
- **Total potential**: 2+ GB in comprehensive sessions

## Time Commitment

Typical maintenance session: 15-30 minutes including diagnostics, cleanup, and documentation.