# Get current Unix timestamp in seconds
echo "Current timestamp: ${EPOCHSECONDS}"

# Get current Unix timestamp with microsecond precision
echo "High precision timestamp: ${EPOCHREALTIME}"

# Practical example: Simple benchmarking
start="${EPOCHREALTIME}"
# ... some operation ...
sleep 0.5
end="${EPOCHREALTIME}"
duration=$(awk "BEGIN {print ${end} - ${start}}")
echo "Operation took ${duration} seconds"

# Example: Log with precise timestamps
log_message() {
    printf '[%s.%06d] %s\n' \
        "$(date -d "@${EPOCHSECONDS}" '+%Y-%m-%d %H:%M:%S')" \
        "${EPOCHREALTIME#*.}" \
        "$*"
}

log_message "Starting process"

# Generate secure random number (if available)
if [[ -n "${SRANDOM}" ]]; then
    secure_random="${SRANDOM}"
    echo "Secure random: ${secure_random}"
else
    echo "SRANDOM not available (requires getrandom/getentropy)"
fi

# Practical example: Generate temporary file with secure random name
temp_file="/tmp/secure_${SRANDOM}_${EPOCHSECONDS}.tmp"

# Open file descriptor and store in variable
exec {fd}< input.txt
while IFS= read -r -u "${fd}" line; do
    echo "Read: ${line}"
done
exec {fd}<&-  # Close the file descriptor

# Practical example: Multiple file handles
exec {input_fd}< data.txt
exec {output_fd}> results.txt
exec {error_fd}> errors.txt

process_data() {
    while IFS= read -r -u "${input_fd}" line; do
        if validate_line "${line}"; then
            echo "Processed: ${line}" >&"${output_fd}"
        else
            echo "Error: ${line}" >&"${error_fd}"
        fi
    done
}

process_data
exec {input_fd}<&-
exec {output_fd}>&-
exec {error_fd}>&-

# Declare associative array with typeset
declare -A config=(
    [host]="localhost"
    [port]="8080"
    [debug]="true"
)

# Enhanced array expansion
for key in "${!config[@]}"; do
    printf '%s=%s\n' "${key}" "${config[${key}]}"
done

# Practical example: Configuration parser
parse_config() {
    declare -gA app_config
    local line key value

    while IFS='=' read -r key value; do
        [[ "${key}" =~ ^[[:space:]]*# ]] && continue  # Skip comments
        [[ -z "${key}" ]] && continue                  # Skip empty lines

        # Trim whitespace
        key="${key#"${key%%[![:space:]]*}"}"
        key="${key%"${key##*[![:space:]]}"}"
        value="${value#"${value%%[![:space:]]*}"}"
        value="${value%"${value##*[![:space:]]}"}"

        app_config["${key}"]="${value}"
    done < config.ini
}

# Configure readline in ~/.inputrc
# Enable case-insensitive completion
set completion-ignore-case on

# Enable visible stats for completions
set visible-stats on

# Show all completions immediately
set show-all-if-ambiguous on

# Use colors for completion matching
set colored-completion-prefix on

# In your script or .bashrc
# Bind Ctrl+R for reverse incremental search (default, but enhanced in 5.1)
bind '"\C-r": reverse-search-history'

# Bind Ctrl+S for forward incremental search
bind '"\C-s": forward-search-history'

# Improved history handling
shopt -s histappend           # Append to history
shopt -s cmdhist              # Multi-line commands as one entry
HISTCONTROL=ignoreboth        # Ignore duplicates and leading spaces
HISTSIZE=10000
HISTFILESIZE=20000

# Enhanced trap handling in subshells
cleanup() {
    echo "Cleaning up..." >&2
    rm -f "${temp_file}"
    exit 130  # 128 + SIGINT
}

trap cleanup SIGINT SIGTERM

temp_file=$(mktemp)

# Signal properly propagates through pipelines
long_running_task | process_output &
pid=$!

# Wait for background job with proper signal handling
wait "${pid}" 2>/dev/null
exit_code=$?

if [[ ${exit_code} -gt 128 ]]; then
    signal=$((exit_code - 128))
    echo "Process terminated by signal ${signal}" >&2
fi

# More reliable subshell variable inheritance
outer_var="parent"

(
    # Subshell now more reliably inherits parent variables
    echo "In subshell: ${outer_var}"
    inner_var="child"
)

# outer_var still accessible, inner_var is not
echo "After subshell: ${outer_var}"

# More reliable glob matching with special characters
shopt -s nullglob  # Empty expansion for non-matching globs
shopt -s extglob   # Extended pattern matching

# Example: Match files but handle no matches gracefully
files=(*.txt)
if [[ ${#files[@]} -eq 0 ]]; then
    echo "No .txt files found"
else
    printf 'Found: %s\n' "${files[@]}"
fi

# Check Bash version before using 5.1 features
if [[ "${BASH_VERSINFO[0]}" -ge 5 ]] && [[ "${BASH_VERSINFO[1]}" -ge 1 ]]; then
    # Safe to use Bash 5.1 features
    timestamp="${EPOCHSECONDS}"
else
    # Fallback for older versions
    timestamp=$(date +%s)
fi