apen

Append from stdin to a new file.

Apen is 7x faster than anewer which a fast rust version of tomnomnom anew.

Usage:

cat 1.txt
one
two
two
one

cat 2.txt
one
line

cat 1.txt | ./apen 2.txt
two

cat 2.txt
one
line
two

Inspierd by anew.
anewer