When automating package management tasks on Debian-based systems, developers frequently encounter this frustrating warning message:

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

This warning appears on STDERR, making it particularly problematic for:

• Cron job notifications
• System monitoring dashboards
• CI/CD pipelines
• Automated update checks

Here are three reliable methods to handle this warning:

1. Redirecting STDERR

sudo apt update 2>/dev/null | grep packages | cut -d '.' -f 1

2. Using APT Configuration

sudo apt -o APT::Update::Warning-Update-Stale-Cache="false" update | grep packages

3. Filtering with grep

sudo apt update 2>&1 | grep -v "WARNING" | grep packages

Here's a robust implementation for your Discord notification:

#!/bin/bash

updates=$(sudo apt update 2>/dev/null | \
          grep -oP '^\d+ packages? can be upgraded' | \
          head -n 1)

if [[ -z "$updates" ]]; then
  echo "All packages are up to date"
else
  echo "$updates"
fi

For those needing more detailed package information:

apt list --upgradable 2>/dev/null | wc -l

Or using aptitude:

aptitude search "~U" | wc -l

• Always test script changes in a development environment
• Consider using apt-get instead of apt for scripting
• Document your approach as APT behavior may change

---

When writing automation scripts that interface with apt, many developers encounter this frustrating warning message:

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

This warning appears on STDERR and can disrupt script output parsing, especially when:

• Building monitoring tools
• Creating automated update notifications
• Developing CI/CD pipelines

Method 1: Redirecting STDERR

The simplest approach is redirecting error output:

sudo apt update 2>/dev/null | grep packages | cut -d '.' -f 1

Method 2: Using APT Config

For a more permanent solution, modify apt configuration:

echo 'APT::Get::Hide-Warning "true";' | sudo tee /etc/apt/apt.conf.d/00suppress-warning

Method 3: Alternative Package Check

For a more robust solution, consider using aptitude or apt-get:

apt-get -s upgrade | grep "^Inst" | wc -l

Here's a complete bash script that handles updates gracefully:

#!/bin/bash

# Suppress apt warnings
export DEBIAN_FRONTEND=noninteractive

# Check for updates (silently)
updates=$(apt-get -qq upgrade -s | grep "^Inst" | wc -l)

# Format output
if [ "$updates" -eq 0 ]; then
  echo "All packages are up to date"
else
  echo "${updates} packages can be updated"
fi

• For production systems, consider logging the warnings separately while suppressing them in output
• The warning exists for good reason - apt's CLI may change between versions
• Alternative tools like aptitude offer more stable interfaces for scripting