When working with apt-get in Debian/Ubuntu systems, the -qq flag is a powerful yet often overlooked option for silent operations. This double quiet flag suppresses almost all output from apt-get, making it particularly useful in automation scripts.

# Basic usage examples:
apt-get update -qq
apt-get install -qq -y package_name

The combination of -qq and output redirection (> /dev/null) serves different purposes:

# -qq alone:
apt-get update -qq  # Only shows critical errors

# With output redirection:
apt-get update > /dev/null  # Redirects all output but still processes messages internally

Here's how you might use these flags in various scenarios:

# In provisioning scripts (like Vagrant):
#!/bin/bash
apt-get update -qq > /dev/null
apt-get install -qq -y apache2 mysql-server > /dev/null

# In CI/CD pipelines:
- name: Install dependencies
  run: sudo apt-get update -qq && sudo apt-get install -qq -y build-essential

While -qq makes operations silent, it doesn't necessarily make them faster. The real performance benefit comes from combining it with -y (auto-confirm) to create completely non-interactive installations:

# Optimal silent installation:
apt-get update -qq && \
apt-get install -qq -y --no-install-recommends \
  package1 \
  package2 \
  package3

For even quieter operations, consider these alternatives:

# Using DEBIAN_FRONTEND (for Debian-based systems):
DEBIAN_FRONTEND=noninteractive apt-get -qq -y install package

# Using apt instead of apt-get (newer systems):
apt -qq -y update && apt -qq -y install package

Since -qq suppresses output, proper error handling becomes crucial:

#!/bin/bash
if ! apt-get update -qq; then
    echo "Update failed" >&2
    exit 1
fi

if ! apt-get install -qq -y package; then
    echo "Installation failed" >&2
    exit 1
fi

Avoid -qq in these situations:

# When debugging installation issues
# When you need to see progress indicators
# When users might need to interact with the process

While reviewing a Vagrantfile provisioning script for an Ubuntu environment, I encountered this pattern:

apt-get update -qq > /dev/null
apt-get -qq -y install apache2 > /dev/null

The -qq flag stands for "very quiet" mode in apt-get. It's actually a doubled -q (quiet) flag, with increasing levels of suppression:

• -q (single): Shows only critical output
• -qq (double): Shows almost nothing (error messages only)

This differs from output redirection (> /dev/null) in several key ways:

# Different suppression techniques comparison:
apt-get install package      # Normal verbose output
apt-get -q install package   # Shows only critical messages
apt-get -qq install package  # Shows only fatal errors
apt-get install package > /dev/null  # Silences ALL output including errors

The combination -qq -y is particularly common in automated deployment scenarios because:

1. It prevents unnecessary output during automated processes
2. It still allows error messages to surface (unlike pure /dev/null redirection)
3. It works well with CI/CD pipelines where excessive output can cause issues

Here's a more complete provisioning example:

#!/bin/bash
# Silent package installation with error handling
if ! apt-get update -qq; then
    echo "Failed to update package lists" >&2
    exit 1
fi

if ! apt-get -qq -y install nginx mysql-server; then
    echo "Package installation failed" >&2
    exit 1
fi

When implementing silent package management:

# Good:
apt-get -qq -y install package || exit 1

# Better (captures stderr separately):
apt-get -qq -y install package 2>error.log || {
    cat error.log >&2
    exit 1
}

# Best (Dockerfile example):
RUN apt-get update -qq \
    && apt-get install -qq -y --no-install-recommends \
        build-essential \
        ca-certificates \
    && rm -rf /var/lib/apt/lists/*