I needed to reverse the order of blank-separated words. GNU tac comes to mind and has an -s-option which lets you set the separator: -s, --separator=STRING use STRING as the separator instead of newline So I tried: $ echo -e A B C D E F | tac -s' ';echo F E D C B A $ echo -e A B C D E F | tac -s' ' | tr ' ' '-';echo F E-D-C-B-A- $ where the final echo is to have the next prompt on a separate line and the tr ' ' '-' is to see any invisible blanks at the end of the output lines. What irritates me is the newline after the "F" in the output. Looks like a bug to me, is it? While writing this question and looking at the suggestions for similar questions (a **very good** feature), I saw https://unix.stackexchange.com/q/598611/268339 and learned about rev, which is exactly what I wanted. Still, for tac, is it a bug or a feature?

Input:

hello
enrico

output:

ocirne
olleh

To do this, I can simply tac a file and pipe the output to rev (or the other way around), so one function that does the job is just this:

revtac() { tac "$@" | rev; }

Is there a built-in function for the job? I suspect that this could potentially break something, as it would reverse ` and ` on Windows-generated files, but I'm still interested.

I am looking to concatenate a list of files in a directory in the reverse order that they appear in the list. This is different from tac as tac will concatenate the files with reversed line order. Basically I have a folder with 3 files, file1, file2 and file3. cat f* > newfile will merge these files like so: file1 file2 file3 However, I want to merge the files like this file3 file2 file1 whilst maintaining the correct line order.

I want to use the tacto reverse a text file character by character. On the info page for coreutils I found an example saying: #Reverse a file character by character tac -r -s 'x\|[^x]' However running tac -r -s seems to open standard input instead of printing the file. What does 'x\|[^x]' mean and what should I be doing? I also noted that the output for tac [file] and tac -r [file] are same and they're the same as cat [file]. Still can't figure out char by char reverse.

> -b, --before > > The separator is attached to the beginning of the record that it > precedes in the file. And I can't understand the following output: $ echo -e "Hello\nNew\nWorld\n!" > file $ tac file ! World New Hello $ tac -b file ! World NewHello Why there is no newline between New and Hello?

I have a file containing "lines" of text, for now only two lines. I need to create a reversed array of these lines - FIFO style. Using "readarray" in this fashion works fine: readarray -t FileArray < "$PWD$DEBUG_DIR$DEBUG_MENU" When I attempt to "reverse" the file I get gibberish: readarray -t FileArray < tac "$PWD$DEBUG_DIR$DEBUG_MENU" I am still learning about substitution and it is obvious I am not using the tac command correctly. I did try different "syntax" without success.