Use `sar`to monitor system usage and log it to a file

start_sar.sh

#!/bin/bash
#####################################################
# Script Name: System Usage Monitor for Raspberry Pi
# Description: This script uses the 'sar' command to monitor system usage on a Raspberry Pi over a specified duration.
# Usage: ./start_sar.sh <custom_name> <interval_in_seconds> <count>
#
# Installation: sudo apt install sysstat
# Source: https://github.com/sysstat/sysstat
#
# Arguments:
#   <custom_name>         : A custom name prefix for the output file.
#   <interval_in_seconds> : Interval between each sample in seconds.
#   <count>               : Total number of samples to be taken.
#
# Output:
#   The output will be a file named `<custom_name>_<start_time>_to_<end_time>.dat` 
#   stored in a directory called `sar` within the user's home directory.
#
# Example:
#   ./start_sar.sh my_monitor 5 60
#   This would monitor the system every 5 seconds, for a total of 60 times.
#####################################################


# Check if the correct number of arguments are provided
if [ "$#" -ne 3 ]; then
    echo "Usage: $0 <custom_name> <interval_in_seconds> <count>"
    exit 1
fi

# Extract arguments
CUSTOM_NAME=$1
INTERVAL=$2
COUNT=$3

# Calculate total duration in seconds
DURATION=$((INTERVAL * COUNT))

# Define the start time in the format YYYYMMDD_HHMMSS
START_TIME=$(date +"%Y%m%d_%H%M%S")

# Calculate the end time based on the given duration
END_TIME=$(date -d "+$DURATION seconds" +"%Y%m%d_%H%M%S")

# Define the directory path and ensure it exists
DIR_PATH="${HOME}/sar"
mkdir -p $DIR_PATH

# Generate the filename
OUTPUT_FILE="${DIR_PATH}/${CUSTOM_NAME}_${START_TIME}_to_${END_TIME}.dat"

# Execute sar
sar -A -o $OUTPUT_FILE $INTERVAL $COUNT > /dev/null 2>&1