tee

Read from stdin and write to stdout and files (or commands). More information: https://www.gnu.org/software/coreutils/manual/html_node/tee-invocation.html.

• Copy stdin to each file, and also to stdout:

echo "example" | tee path/to/file

• Append to the given files, do not overwrite:

echo "example" | tee -a path/to/file

• Print stdin to the terminal, and also pipe it into another program for further processing:

echo "example" | tee /dev/tty | xargs printf "[%s]"

• Create a directory called "example", count the number of characters in "example" and write "example" to the terminal:

echo "example" | tee >(xargs mkdir) >(wc -c)