sed

Edit text in a scriptable manner. See also: awk, ed. More information: https://keith.github.io/xcode-man-pages/sed.1.html.

• 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_file.sed

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

command | sed -E 's/(apple)/\U\1/g'

• Print just a first line to stdout:

command | sed -n '1p'

• Replace all apple (basic regex) occurrences with mango (basic regex) in a file and save a backup of the original to file.bak:

sed -i bak 's/apple/mango/g' path/to/file