Command Form: >>

Use

printf 'again\n' >> ~/playground/hi.txt

What It Does

>> sends stdout to the end of a file. It creates the file if needed and preserves existing content.

Practice

printf 'first\n' > ~/playground/hi.txt
printf 'second\n' >> ~/playground/hi.txt
cat ~/playground/hi.txt

Both lines remain because only the first command overwrites.

Watch Out

Appending generated output repeatedly can create duplicates. If output should be idempotent, generate the full file from source instead of appending fragments forever.

Docs Pointers

• Read overwrite redirection, I/O, file descriptors, and stream redirection.