In Bash, you can strip the last consecutive newlines from a string or file using sed or parameter expansion. Here are a few ways:

1. Using sed (for files or strings)

To remove only the trailing newlines at the end of a file or string:

sed -i -e :a -e '/^\n*$/{$d;N;ba' -e '}' file.txt

• -i: Edit the file in-place.
• The command removes only the trailing newlines at the end of the file.

For a string (not a file):

echo -e "hello\n\n\n" | sed -e :a -e '/^\n*$/{$d;N;ba' -e '}'

2. Using Bash Parameter Expansion (for strings)

If you have a string in a variable and want to remove only the trailing newlines:

str="hello

"
str="${str%$'\n'*}"
echo "$str"

• % removes the shortest match of the pattern from the end.
• $'\n'* matches one or more newlines at the end.

3. Using awk (for files)

To remove only the trailing newlines in a file:

awk 'NR>1 && /^$/ {prev=$0; next} {print prev; prev=$0} END {if (prev != "") print prev}' file.txt > temp && mv temp file.txt