README.md

chapter 4 : practice

## chapter 4 : practice

Example 1:

Create a Bash script that checks if a specific process (e.g., sshd) is running and prints a message based on its status.

Steps: 1- Create a Bash script that checks if a specified process is running using the pgrep command. 2- Print a message indicating whether the process is running or not.

Note: --pgrep command in Linux is a powerful tool used to find processes based on their name and other attributes.

Script:

#!/bin/bash

# Name of the process to check
PROCESS_NAME="sshd"

# Check if the process is running
if pgrep "$PROCESS_NAME" > /dev/null; then
    echo "$PROCESS_NAME is running."
else
    echo "$PROCESS_NAME is not running."
fi

Example 1 : Execusion process

cd chapter4
chmod +x example1.sh
./example1.sh

---

Example 2: Killing Processes by Name

Create a Bash script that kills all processes with a specified name.

Steps: Prompt the user to enter the name of the process to kill. Use the pkill command to kill all processes with that name. Print a message indicating the result.

Script:

#!/bin/bash

# Prompt the user to enter the name of the process to kill
read -p "Enter the name of the process to kill: " process_name

# Kill all processes with the specified name
if pkill "$process_name"; then
    echo "All processes named '$process_name' have been killed."
else
    echo "Failed to kill processes named '$process_name'. Please check the process name and try again."
fi

Example 2 : Execusion process

cd chapter4
chmod +x example2.sh
./example2.sh

---

Example 3: Logging Background Process Output

Create a Bash script that launches a background process and logs its output to a file.

Steps: 1- Create a Bash script that spawns a background process. 2- The background process should perform a task (e.g., counting to a number) and log its output to a file. 3- The main script should wait for the background process to complete.

#!/bin/bash

# Log file to store the output
LOG_FILE="process.log"
COUNT_TO=10

# Function for background process
background_process() {
    for ((i=1; i<=COUNT_TO; i++)); do
        echo "Process $$: $i" >> "$LOG_FILE"
        sleep 1
    done
}

# Create background process and log its output to a file
background_process &
# Wait for the background process to complete
wait
echo "Background process has completed. Check $LOG_FILE for output."

Example 3 : Execusion process

cd chapter4
chmod +x example3.sh
./example3.sh

---

Example 4: Monitoring Multiple Processes ("sshd" "cron" "nginx")

Create a Bash script that monitors multiple processes and prints a message if any of them are not running. Steps: Create a Bash script that monitors multiple processes by name. Use the pgrep command to check if each process is running. Print a message if any process is not running.

Script:

#!/bin/bash

# List of processes to monitor
PROCESSES=("sshd" "cron" "nginx")

# Monitor each process
for process in "${PROCESSES[@]}"; do
    if pgrep "$process" > /dev/null; then
        echo "$process is running."
    else
        echo "$process is not running."
    fi
done

Example 2 : Execusion process

cd chapter4
chmod +x example4.sh
./example4.sh