Best way to remove last line-feed in text file

sed '$d' < file1 > file2; mv file2 file1

"$" means the last line with sed. "d" is delete.

sed does have the ability to edit in place with a backup using the -i switch, but it's risky, so I stick with the write and move method.

What is the best way to remove last line-feed in text file? (so that the last line of text is the last line, not a line-feed). The best I can come up with is: echo -n "$(cat file.txt)" > newfile.txt
(as echo -n will remove all trailing newline characters)

According to my experiments, you have removed all line terminators from the file, and replaced those between lines with a space.

That is to say, you have turned a multi-line file into one long line with no line terminator.

If that is what you want, and your files are not very big, then your echo statement might be all you need.

If you need to deal with larger files, you could try using the 'tr' command, and something like

tr ' ' ' ' <file.txt >newfile.txt

The only problem with this is, it will most likely give you a trailing space, as the last newline is going to be converted to a space. If that is not acceptable, then something else will have to be arranged.

However, if you really want to maintain a multi-line file, but remove just the very last line terminator, that gets a bit more complicated. This might work for you:

perl -ne '
 chomp;
 print " " if $n++ != 0;
 print;
' file.txt >newfile.txt

You can use cat -e to see which lines have newlines, and you should see that the last line does not have a newline, but all the others still do.

I guess if you really did mean to remove all newline characters and replace them with a space, except for the last line, then a modification of the above perl script would do that:

perl -ne '
 chomp;
 print " " if $n++ != 0;
 print;
' file.txt >newfile.txt

Am I even close to understanding what you are asking for?

sed '$d' < file1 > file2; mv file2 file1

That actually deletes the last line, and not just the trailing linefeed.

But then again, I'm unclear as to exactly what is desired, so your solution could be right.

How about using dd to get rid of the file's last newline character?

file='/path/to/file'
[[ "$(tail -c 1 "${file}" | tr -dc ' ' | wc -c)" -eq 1 ]] && 
 printf "" | dd of="${file}" seek=$(($(stat -f "%z" "${file}") - 1)) bs=1 count=1
tail -c 10 "${file}"; echo

file='/path/to/file'
[[ "$(tail -c 1 "${file}" | tr -dc ' ' | wc -c)" -eq 1 ]] && 
 printf "" | dd of="${file}" seek=$(($(stat -f "%z" "${file}") - 1)) bs=1 count=1
tail -c 10 "${file}"; echo

While that is extremely convoluted, I did learn something about dd I never realized before. The following is from the dd man page:

... If an initial portion of the output file is
seeked past (see the oseek operand), the output file is trun-
cated at that point.

My hat goes off to you 🙂