Mastering Intermediate Linux Commands for Efficient Server Management

Introduction

As a sysadmin, you often come across complex tasks that require more than just basic commands. That’s why it’s important to learn some intermediate-level Linux commands that can make your work easier and more efficient.

These commands can help you automate repetitive tasks, manage processes, and monitor system performance, among other things. In this article, we will explore some of these commands and their usage.

Monitoring and Performance

• sar - The sar command is used to collect, report, and save system activity information.

  It is helpful for monitoring system performance and diagnosing issues.

  sar -u 5 10

  This command will display CPU utilization statistics every 5 seconds, 10 times.

• atop - The atop command is used to monitor system resources and processes.

  It provides a detailed view of the system activity and helps in identifying performance bottlenecks.

  atop -r /var/log/atop/atop_20230301

  This command will display the system activity for a specific date.

• free - Display the amount of free and used memory in the system.

  free -h

  This will display the data in a human-readable format.

Process Management

• ps - Display information about the currently running processes.

  ps -aux

• kill - Send a signal to a process, which can be used to terminate the process.

  kill -9 1234

  This will kill the process which has the PID of 1234

• pkill - Kill processes based on their name or other attributes.

  pkill -f firefox

  This will kill the firefox process.

• nice - nice command is used to set the priority of a process.

  It is often used to give lower priority to CPU-intensive processes so that they don’t hog the system resources.

  nice -5 wget https://akashrajpurohit.com

  To set negative priority you can use a double hyphen

  nice --5 wget https://akashrajpurohit.com

• renice - Change the priority of an already running process.

  renice +5 1234

  This will change the priority of the process with PID 1234.

• top - Displays real-time information about running processes and system resources.

  top

Networking Commands

• traceroute - Traces the route taken by packets over an IP network.

  traceroute google.com

• tcpdump - Captures network traffic in real-time and saves it to a file.

  tcpdump -i eth0 -w capture.pcap

• netstat - Displays information about network connections, routing tables, and network interfaces.

  netstat -ano | grep ESTABLISHED

• nmap - Scans a network and discovers open ports and services.

  nmap -sS -O 192.168.1.1/24

Disk Management

• lsof - The lsof command is used to list open files on the system. It is helpful for identifying processes that are using a specific file or disk partition.

  lsof /dev/sda1

  This command will list all processes that are using the /dev/sda1 disk partition.

• blkid - The blkid command is used to display information about block devices. It is helpful for identifying disk partitions and their properties.

  blkid /dev/sda1

  This command will display the properties of the /dev/sda1 disk partition.

• fdisk - fdisk command is used to list, create, delete, or modify partitions on a hard disk.

  fdisk -l

  This command will list the partition tables for the hard drive.

Miscellaneous Commands

• sed - A stream editor for filtering and transforming text.

  sed 's/foo/bar/g' input.txt > output.txt

• awk - A versatile programming language for text processing and data extraction.

  cat access.log | awk '{ print $1 }'

• tar - A utility for creating and manipulating tar archives.

  tar -czvf archive.tar.gz file1 file2 dir1

• find - Searches for files and directories that match certain criteria.

  find /var/log -type f -name "*.log" -mtime +7 -exec rm {} \;

Conclusion

These are some of the intermediate-level Linux commands that a system admin may use while maintaining a Linux server.

However, this is not an exhaustive list, and there are many more commands that you can explore as you become more experienced with Linux administration.

If you are someone who manages Linux servers a lot and want to add/edit some of the commands then do let me know by reaching out on any social media platform.