20 most used Linux commands to troubleshoot issues

Using the below commands effectively allows for comprehensive troubleshooting and monitoring of a Linux system, helping to quickly identify and resolve issues.

System Performance and Resource Usage

1. top: Provides a dynamic, real-time view of the system’s processes. Useful for checking CPU and memory usage.

   top
   

2. htop: An enhanced version of top, with a more user-friendly interface (if installed).

   htop
   

3. free -m: Displays memory usage, with -m showing the information in megabytes.

   free -m
   

4. vmstat: Reports virtual memory statistics.

   vmstat 5
   

5. iostat: Provides CPU and I/O statistics. Useful for diagnosing disk performance issues.

   iostat
   

Disk Usage and Space

1. df -h: Shows disk space usage in a human-readable format.

   df -h
   

2. du -sh *: Displays the disk usage of files and directories in the current directory, summarized and human-readable.

   du -sh *
   

Network

1. ping: Checks the network connectivity between the host and a target IP or domain.

   ping google.com
   

2. netstat -tuln: Lists all listening ports and their respective services.

   netstat -tuln
   

3. ss -tuln: A modern replacement for netstat, displaying listening sockets.

   ss -tuln
   

4. traceroute: Traces the route packets take to a network host.

   traceroute google.com
   

5. ifconfig or ip addr: Displays network interfaces and their configurations.

   ifconfig
   ip addr
   

Processes and Services

1. ps aux: Lists all running processes with detailed information.

   ps aux
   

2. systemctl status <service>: Checks the status of a specific service.

   systemctl status apache2
   

3. journalctl -xe: Views system logs, particularly useful for diagnosing issues with services managed by systemd.

   journalctl -xe
   

Logs and Files

1. tail -f /var/log/syslog: Monitors the system log file in real-time.

   tail -f /var/log/syslog
   

2. dmesg: Displays kernel-related messages.

   dmesg
   

System Information

1. uname -a: Displays detailed information about the system, including the kernel version.

   uname -a
   

2. uptime: Shows how long the system has been running, along with the load average.

   uptime
   

3. lsof: Lists open files and the processes that opened them. Useful for troubleshooting issues related to files and directories.

   lsof
   

If there are any other commands you use on a regular basis that’s not listed above, please feel free to comment.