POSIX 7 http://pubs.opengroup.org/onlinepubs/9699919799/utilities/tail.html
Opposite of head.
Keep only 2 last lines:
[ "$(printf '1\n2\n3\n4\n5\n' | tail -n2)" = "$(printf '4\n5\n')" ] || exit 1
Same with negative sign:
[ "$(printf '1\n2\n3\n4\n5\n' | tail -n-2)" = "$(printf '4\n5\n')" ] || exit 1
Same without the -n:
[ "$(printf '1\n2\n3\n4\n5\n' | tail -2)" = "$(printf '4\n5\n')" ] || exit 1
Keep all lines starting from the second:
[ "$(printf '1\n2\n3\n4\n5\n' | tail -n+2)" = "$(printf '2\n3\n4\n5\n')" ] || exit 1
Operate on bytes instead of lines:
[ "$(printf '12345' | tail -c2)" = "$(printf '45')" ] || exit 1
Keep only lines from the Nth onwards:
[ "$(printf "1\n2\n3\n4\n" | tail -n +2)" = "$(printf "2\n3\n4\n")" ] || exit 1
[ "$(printf "1\n2\n3\n4\n" | tail -n +3)" = "$(printf "3\n4\n")" ] || exit 1