To append text to a file when using the sudo command on a Linux or Unix system, you can use the echo command and the sudo tee command. Here's an example of the command you can use:
echo "Some text to append" | sudo tee -a /path/to/file
This command will append the text "Some text to append" to the file located at /path/to/file. The echo command is used to print the text to be appended, and the tee command is used to redirect the output of the echo command to the file. The -a option is used to tell tee to append the output to the file, rather than overwriting it.
It's worth noting that you will need to use the sudo command to run the tee command with the necessary privileges to write to the file, since the file is likely to be owned by the root user or another user with higher privileges.
You can also use this same technique to append the output of other commands to a file. For example, you could use the following command to append the output of the ls command to a file:
ls | sudo tee -a /path/to/file
This will append the output of the ls command (i.e., a list of the files in the current directory) to the file located at /path/to/file.
It's worth noting that the tee command has many other options and features that can be used to control how it handles the output it receives. You can use the man tee command to learn more about these options and how to use the tee command.