How to add filename to end of every line - all files in all subdirectories

With GNU awk:

LC_ALL=C find . -type f -exec gawk -i inplace '
  BEGINFILE {suffix = FILENAME; sub(/.*//, "", suffix)}
  {print $0, suffix}' {} +

Beware that if there are several hard links of the same file, the name for each will be added (in no particular order) to each line of that file.

Try this, using find and sed:

find /path/to/top_directory -type f -execdir sed -i -e "s/$/ {}/" {} ;

Replace /path/to/top_directory with the directory where the files you want to edit are.

With perl and find

find . -type f -exec perl -i -pe 's/$/ $ARGV/' {} +

• s/$/ $ARGV/ add space and filename to end of each line
• -i for inplace editing, use i.bkp if you want to retain a backup of original files
• If your find doesn't support +, use ; instead
• find . -type f will give list of all files in current directory
• -exec allows to use a command to act upon all those files
• Use find . -type f -name '*.txt' if you want to restrict to only files ending with .txt

Thanks @thiagowfx for pointing that above solution will add filename as ./file.txt, ./foo/file2.txt, etc

Use this to add only filename without any ./ etc

find . -type f -exec perl -i -pe 's/$/$ARGV=~s|.*/| |r/e' {} +

• $ARGV=~s|.*/| |r will give filename with all characters upto / removed