BASH: Ways of Piping/Redirection and Heredoc Demonstration

ways_of_piping_and_redirection.sh

# shells are an orchestration environment
# the language they provide is intended to orchestrate processes
# on the operating system
# if programs are functions, then all of the below are variants of function application

# anonymous pipe
echo "string" | cat

# herestring
cat <<< "string"

# herestring with command substitution
cat <<< $(echo "string")

# redirect stdin from process substitution
cat < <(echo "string")

# heredoc
cat << EOF
string
EOF

# heredoc ignoring leading tabs on each line
cat <<- EOF
	string
EOF

# heredoc literal - ignores interpolation and evaluation
cat << 'EOF'
$string
EOF

heredoc with pipe

cat <<'EOF' |  sed 's/l/e/g'
Hello
World
EOF