System Monitoring Script

This script provides a simple way to monitor your system's CPU, memory, disk usage, and network activity using zsh on macOS. It collects and displays these metrics in a report format.

Script Explanation

Shebang

#!/bin/zsh

The shebang (#!) specifies the path to the zsh interpreter. This tells the system to use zsh to execute the script.

Functions

1. Get CPU Usage

get_cpu_usage() {
    local cpu_usage=$(top -l 1 | grep "CPU usage" | awk '{print $3 + $5}')
    echo "CPU Usage: $cpu_usage%"
}

top -l 1: Runs the top command in batch mode and outputs one iteration of the report.
grep "CPU usage": Filters the output to lines containing "CPU usage".
awk '{print $3 + $5}': Uses awk to sum the user and system CPU usage percentages (assuming top output format).
echo "CPU Usage: $cpu_usage%": Prints the calculated CPU usage.

2. Get Memory Usage

get_memory_usage() {
    local mem_used=$(vm_stat | grep 'Pages active' | awk '{print $3}' | sed 's/\.//')
    local mem_free=$(vm_stat | grep 'Pages free' | awk '{print $3}' | sed 's/\.//')
    local mem_total=$(vm_stat | grep 'Pages wired down' | awk '{print $4}' | sed 's/\.//')
    mem_total=$((mem_total + mem_used + mem_free))
    local mem_usage=$(echo "scale=2; ($mem_used + $mem_total)*4/1024/1024" | bc)
    echo "Memory Usage: $(($mem_used*4/1024)) MB / $((($mem_used + $mem_total)*4/1024)) MB ($mem_usage%)"
}

vm_stat: Provides virtual memory statistics.
grep 'Pages active': Filters output for active memory pages.
awk '{print $3}': Extracts the number of active pages.
sed 's/.//': Removes the trailing period from the number.
Calculations: Adds up memory pages (active, free, wired) and converts to MB.
bc: Basic calculator for floating-point arithmetic. echo: Prints the memory usage.

3. Get Disk Usage

get_disk_usage() {
    local disk_usage=$(df -h / | awk 'NR==2 {print $5}')
    echo "Disk Usage: $disk_usage"
}

df -h /: Displays disk space usage for the root directory in human-readable format.
awk 'NR==2 {print $5}': Extracts the usage percentage from the second line.
echo "Disk Usage: $disk_usage": Prints the disk usage.

4. Get Network Activity

get_network_activity() {
    local net_activity=$(netstat -ib | awk '/en0/{print "In: " $7/1024 " KB, Out: " $10/1024 " KB"}')
    echo "Network Activity: $net_activity"
}

netstat -ib: Displays network statistics including interface information.
awk '/en0/{print "In: " $7/1024 " KB, Out: " $10/1024 " KB"}': Filters for en0 interface and calculates KB from bytes for input and output.
echo "Network Activity: $net_activity": Prints the network activity.

Main Monitoring Function

monitor_system() {
    echo "System Monitoring Report"
    echo "-------------------------"
    get_cpu_usage
    get_memory_usage
    get_disk_usage
    get_network_activity
    echo "-------------------------"
}

echo "System Monitoring Report": Prints the report header.
Function Calls: Executes each function to collect and print system metrics.
echo "-------------------------": Prints a separator.

Execution

Run the monitoring function monitor_system

This calls the monitor_system function to execute the monitoring tasks and print the report.

SKG24/System-Monitoring-Script