2021
https://www.reddit.com/r/commandline/comments/ra4dg7/extremely_useful_alias_i_just_came_up_with/
    alias linedo="xargs -d '\n' -I {}" 

xargs -t kill
	print the command line on stderr before executing

-a, --arg-file
    read args from the file

-0, --null
    items are separated by a null, not whitespace;
    disables quote and backslash processing and logical EOF processing

-I R
    same as --replace=R
-i, --replace[=R]
    replace R in INITIAL-ARGS with names read from standard input;
    if R is unspecified, assume {}
-P, --max-procs 40
    use 40 threads
-t, --verbose


the same:
xargs -0 -a 1.txt echo
xargs -0 -I{} -a 1.txt echo {} 
xargs -0 -i -a 1.txt echo {}

samples
cat lines.txt | xargs -0 -n 1 echo
    ???
cat lines.txt | xargs -n 1 echo
find *.txt | xargs -i sh -c "cat {}; echo ''" > finalfile.txt
xargs -0 -i -P 4 -a ~/Downloads/1.txt echo {}