`strace` is a powerful command-line tool used to trace and debug system calls and signals made by a running process. It allows you to observe and analyze the interactions between a process and the operating system, providing insights into its behavior and troubleshooting potential issues. Here’s a refresher on using `strace` with an already running script:
ps -ef | grep scriptname
This will display a list of processes that match the name of the script. Identify the correct process and note its PID.
ย Attach `strace` to the Running Script: Once you have the PID, you can attach `strace` to the running script using the `-p` option, followed by the PID. For example:ย ย ย
strace -p <pid></pid>
This will start tracing system calls and signals made by the running script.
Observe the `strace` Output: `strace` will start printing the system calls and signals made by the script in real-time. It provides detailed information, including the call type, arguments, return values, and any errors encountered. This output can help you understand the behavior of the script and identify any issues or unexpected behavior.
Analyze the `strace` Output: Analyze the output of `strace` to gain insights into the script’s behavior. Look for any errors or unusual system calls that might indicate problems. Pay attention to specific system calls like `open`, `read`, `write`, `fork`, `exec`, and others, depending on the script’s functionality. The output can help you diagnose issues, identify performance bottlenecks, or trace the flow of execution within the script.
Detach `strace`: To detach `strace` from the script, use the keyboard shortcut `Ctrl + C`. This will stop tracing the script’s system calls and signals.
strace -p <pid> -o strace_output.txt</pid>