40 lines
2 KiB
Bash
40 lines
2 KiB
Bash
# Set up the terminal to read input immediately, without waiting for Enter.
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# This is done using the `stty` command.
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# `stty` controls terminal settings.
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# `-icanon` disables canonical mode. In canonical mode, the terminal buffers input until a newline is received. Disabling it makes input available immediately.
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# `min 1` specifies that at least 1 character should be read.
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# `time 0` specifies that the read should return immediately if a character is available.
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stty -icanon min 1 time 0
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# Prompt the user to enter 'y' or 'n' to confirm or cancel the poweroff.
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# `echo -n` prints the prompt without a trailing newline, so the input will appear on the same line.
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echo -n "Poweroff system? (y/n) [n]: "
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# Read a single character from the input and store it in the 'answer' variable.
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# `read -n 1 answer` reads only 1 character.
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read -n 1 answer
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# Print a newline character after the input has been read.
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# This makes the output more readable, as the subsequent messages will appear on a new line.
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echo
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# Restore the terminal settings to their default values.
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# This is important, as leaving the terminal in non-canonical mode can cause unexpected behavior.
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# `stty icanon` re-enables canonical mode.
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stty icanon
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# Check the value of the 'answer' variable.
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# `[[ ... ]]` is a more robust and feature-rich way to perform conditional tests than `[ ... ]`.
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# `"y"` matches only the lowercase "y". If you want case-insensitive matching, consider using `[[ ${answer,,} == "y" ]]` (converts answer to lowercase).
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if [[ "$answer" == "y" ]]; then
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# If the user entered 'y', proceed with the poweroff.
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echo "Powering off..."
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# Execute the systemctl poweroff command with root privileges using sudo.
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# `sudo` allows you to run commands as the superuser (root).
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# `systemctl poweroff` sends the command to the systemd init system to shut down the machine.
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sudo systemctl poweroff
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else
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# If the user entered anything other than 'y', cancel the poweroff.
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echo "Poweroff cancelled."
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fi
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