Files and Pipelines
Redirects
Writing and Reading Files
Redirection connects command output and input to files. Scripts use it for temporary data, reports, and logs.
Program
Play the script to watch text move into a file and a line count come back out.
redirects.sh
#!/usr/bin/env bash
file="$(mktemp)"
printf 'alpha\nbeta\n' > "$file"
lines="$(wc -l < "$file")"
rm "$file"
echo "lines=$lines"
redirection
`>` writes stdout to a file and `<` reads stdin from a file.
temporary file
`mktemp` creates a unique path for short-lived script data.