python - How to properly redirect stdout/stderr from a systemd service on Raspbian?

Python - How to properly redirect stdout/stderr from a systemd service on Raspbian?

Redirecting stdout and stderr from a systemd service on Raspbian involves modifying the service unit file to control where the output is logged. Here are the steps:

  1. Edit the Service Unit File: Open or create the systemd service unit file for your service. This file is typically located in the /etc/systemd/system/ directory and has a .service extension.

    sudo nano /etc/systemd/system/your_service_name.service

  2. Configure Standard Output and Standard Error: In the service unit file, add or modify the StandardOutput and StandardError options to control where the output is directed.

    For example, to redirect both stdout and stderr to a file:

    [Service] ExecStart=/path/to/your_executable StandardOutput=file:/path/to/your_log_file.log StandardError=file:/path/to/your_error_log_file.log

    To redirect both stdout and stderr to the systemd journal:

    [Service] ExecStart=/path/to/your_executable StandardOutput=journal StandardError=journal

    To redirect both stdout and stderr to the null device (discard output):

    [Service] ExecStart=/path/to/your_executable StandardOutput=null StandardError=null

  3. Reload and Restart systemd: After modifying the service unit file, reload the systemd configuration and restart your service:

    sudo systemctl daemon-reload sudo systemctl restart your_service_name

    Make sure to replace your_service_name with the actual name of your service.

  4. View the Logs: Depending on your configuration, you can view the logs using the journalctl command. For example:

    journalctl -u your_service_name

    Replace your_service_name with the actual name of your service.

    If you redirected the output to a file, you can view the content of the log file:

    cat /path/to/your_log_file.log

    Replace /path/to/your_log_file.log with the actual path to your log file.

These steps should help you properly redirect stdout and stderr from your systemd service on Raspbian. Choose the redirection option that best fits your needs, whether it's redirecting to a file, the systemd journal, or discarding the output.

Examples

  1. "Systemd service redirect stdout stderr Python"

    • Code:
      [Service] Type=simple ExecStart=/path/to/your/python/script.py > /path/to/log/output.log 2>&1
    • Description: Redirecting both stdout and stderr to a log file using the > and 2>&1 syntax in the systemd service configuration.

  2. "Python systemd service redirect stdout to file"

    • Code:
      [Service] Type=simple StandardOutput=file:/path/to/log/output.log ExecStart=/path/to/your/python/script.py
    • Description: Using StandardOutput to directly specify redirecting stdout to a file in the systemd service configuration.

  3. "Redirect Python script output to journal with systemd"

    • Code:
      [Service] Type=simple ExecStart=/path/to/your/python/script.py StandardOutput=journal StandardError=journal
    • Description: Redirecting both stdout and stderr to the systemd journal for logging.

  4. "Systemd service redirect stdout to syslog Python"

    • Code:
      [Service] Type=simple ExecStart=/path/to/your/python/script.py StandardOutput=syslog StandardError=syslog
    • Description: Redirecting both stdout and stderr to the system log (syslog) using systemd configuration.

  5. "Redirect Python script output to file with timestamp"

    • Code:
      [Service] Type=simple ExecStart=/bin/bash -c "/path/to/your/python/script.py > /path/to/log/output_$(date +\%Y\%m\%d_\%H\%M\%S).log 2>&1"
    • Description: Redirecting stdout and stderr to a log file with a timestamp in the filename using the date command.

  6. "Systemd redirect stdout to journal and stderr to file"

    • Code:
      [Service] Type=simple ExecStart=/path/to/your/python/script.py StandardOutput=journal StandardError=file:/path/to/log/error.log
    • Description: Redirecting stdout to the systemd journal and stderr to a file in the systemd service configuration.

  7. "Python systemd service custom log file rotation"

    • Code:
      [Service] Type=simple ExecStart=/path/to/your/python/script.py StandardOutput=file:/path/to/log/output.log StandardError=file:/path/to/log/error.log
    • Description: Configuring custom log file paths for both stdout and stderr in the systemd service configuration.

  8. "Systemd service redirect stdout stderr to null"

    • Code:
      [Service] Type=simple ExecStart=/path/to/your/python/script.py > /dev/null 2>&1
    • Description: Redirecting both stdout and stderr to /dev/null to discard the output.

  9. "Systemd service redirect stdout stderr to FIFO file"

    • Code:
      [Service] Type=simple ExecStart=/bin/bash -c "/path/to/your/python/script.py > /path/to/fifo 2>&1"
    • Description: Redirecting both stdout and stderr to a FIFO (named pipe) file.

  10. "Python systemd service tee stdout to file"

    • Code:
      [Service] Type=simple ExecStart=/bin/bash -c "/path/to/your/python/script.py 2>&1 | tee /path/to/log/output.log"
    • Description: Using tee to duplicate stdout to both the terminal and a log file in the systemd service configuration.

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