Using the setserial Command (with examples)

The setserial command is a powerful tool for managing and configuring serial ports in Linux. It allows you to read and modify information related to serial devices, such as baud rates, flow control, and interrupt handling. In this article, we will explore four different use cases of the setserial command, along with code examples, motivations, explanations, and example outputs for each.

1: Print all information about a specific serial device

Code:

setserial -a /dev/cuaN

Motivation: Printing all information about a specific serial device can be useful when troubleshooting or verifying the configuration of a particular serial port. It provides a comprehensive overview of the settings and parameters associated with the device.

Explanation: The -a option instructs setserial to display all information about the specified serial device. /dev/cuaN represents the path of the serial device file you want to investigate.

Example Output:

/dev/cuaN, Line 0, UART: 16550A, Port: 0x3f8, IRQ: 4
    Baud_base: 115200, close_delay: 50, divisor: 0
    closing_wait: 3000, dtr: on, flags: sgio

2: Print the configuration summary of a specific serial device

Code:

setserial -b device

Motivation: Printing the configuration summary of a serial device can be useful when you need a concise overview of the device settings during the bootup process or when troubleshooting. It provides a quick snapshot of key parameters related to the serial port.

Explanation: The -b option tells setserial to print the configuration summary of the specified serial device. Replace device with the actual name/path of the device you want to examine.

Example Output:

/dev/ttyS0, UART: 16550A, Port: 0x3f8, IRQ: 4
    Baud_base: 115200, close_delay: 50, divisor: 0
    closing_wait: 3000, dtr: on, flags: sgio

3: Set a specific configuration parameter to a device

Code:

sudo setserial device parameter

Motivation: Setting a specific configuration parameter to a serial device allows you to customize the behavior of the port to meet specific requirements. For example, you may need to adjust the baud rate, flow control, or other settings to establish a reliable communication link.

Explanation: In this command, device refers to the name/path of the serial device you wish to configure, while parameter represents the specific setting or parameter you want to modify. The sudo command is used to run setserial with administrative privileges, as modifying serial device settings typically requires root access.

Example Output:

No output is expected for this command.

4: Print the configuration of a list of devices

Code:

setserial -g device1 device2 ...

Motivation: Printing the configuration of a list of serial devices comes in handy when you want to quickly obtain the settings of multiple serial ports. It saves time by providing a consolidated view of the configurations, allowing you to compare and analyze them efficiently.

Explanation: The -g option tells setserial to print the configuration of multiple serial devices. Replace device1, device2, etc., with the names/paths of the serial devices you want to examine. You can specify as many devices as required, separated by spaces.

Example Output:

/dev/ttyS0, UART: 16550A, Port: 0x3f8, IRQ: 4
    Baud_base: 115200, close_delay: 50, divisor: 0
    closing_wait: 3000, dtr: on, flags: sgio

/dev/ttyS1, UART: unknown, Port: 0x2f8, IRQ: 3
    Baud_base: 9600, close_delay: 50, divisor: 0
    closing_wait: 3000, dtr: on, flags: sgio

Conclusion:

The setserial command provides a wide range of capabilities for managing and configuring serial ports in Linux. By understanding how to use this command and its various options, you can effectively control and troubleshoot your serial devices. Use the examples and explanations provided in this article as a reference to get started with using setserial in your own projects.