sed

Edit text in a scriptable manner. See also: awk, ed. More information: https://manned.org/sed.1posix.

• Replace all apple (basic regex) occurrences with mango (basic regex) in all input lines and print the result to stdout:

command | sed 's/apple/mango/g'

• Execute a specific script [f]ile and print the result to stdout:

command | sed -f path/to/script.sed

• Print just a first line to stdout:

command | sed -n '1p'