Unix command to copy last line of file to another file

Please provide a command to append an ex开发者_如何学Goisting file by taking a last line of another file.

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tail -n 1 $file1 >> $file2

Though most systems also support

tail -1 $file1 >> $file2

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tail $file1 -n 1 >> $file2

Or,

tail -1 $file1 >> $file2

If you want it to work with sudo:

tail -1 $file1 | tee -a $file2