CLI tip 27: reverse text line wise with tac

You can use tac to reverse the input line wise. If you pass multiple input files, each file content will be reversed separately.

$ printf 'apple\nbanana\ncherry\nfig and honey\n' | tac
fig and honey
cherry
banana
apple

You can use the -s option to specify a different string to be used as the line separator (newline is the default separator). When the custom separator occurs before the content of interest, use the -b option to print those separators before the content in the output as well.

$ cat blocks.txt
%=%=
apple
banana
%=%=
1
2
3
%=%=
red
green

$ tac -b -s '%=%=' blocks.txt
%=%=
red
green
%=%=
1
2
3
%=%=
apple
banana

info See CLI tip 8: extract from start of file until matching line for a practical example where reversing input content helps in constructing a solution.

Video demo:

info See also tac section from my Command line text processing with GNU Coreutils ebook for more details and examples.