Search Log Files for Patterns with Context

#!/bin/bash

# Configuration
DEFAULT_LOG_DIR="/var/log" # Default directory to search
CONTEXT_LINES=5 # Number of lines before and after the match
SEARCH_OPTIONS="-E -i -C $CONTEXT_LINES" # grep options (Extended regex, case-insensitive, Context)

# Function to display usage
usage() {
  echo "Usage: $0 <pattern> [log_directory]"
  echo "  <pattern>: The regular expression to search for."
  echo "  [log_directory]: Optional. The directory to search logs in. Defaults to $DEFAULT_LOG_DIR."
  exit 1
}

# Check for required argument
if [ -z "$1" ]; then
  usage
fi

SEARCH_PATTERN="$1"
LOG_DIR=${2:-$DEFAULT_LOG_DIR} # Use provided directory or default

if [ ! -d "$LOG_DIR" ]; then
  echo "Error: Log directory '$LOG_DIR' not found."
  exit 1
fi

echo "Searching for pattern '$SEARCH_PATTERN' in '*.log*' files under '$LOG_DIR' (with $CONTEXT_LINES lines of context)..."

# Find all .log files (including compressed .log.gz, .log.1, etc.) and grep them
# -print0 and xargs -0 handle filenames with spaces correctly
find "$LOG_DIR" -type f \( -name "*.log" -o -name "*.log.*" -o -name "*.gz" \) -print0 | xargs -0 zgrep $SEARCH_OPTIONS "$SEARCH_PATTERN" 2>/dev/null

# Check grep exit status
if [ $? -eq 0 ]; then
  echo "
Search complete: Matches found."
elif [ $? -eq 1 ]; then
  echo "
Search complete: No matches found for '$SEARCH_PATTERN'."
else
  echo "
Search completed with errors (e.g., inaccessible files)."
  exit 1
fi