하나의 리다이렉션 연산자가 나에게 명확하지 않다. <<

Question

<<의 사용법은 분명하지 않다. 간단한 예제로 설명 할 수 있을까? 정말 고맙습니다.

Answer 1

cat <<'EOF' 
hello $$ 
I'm a here document that doesn't interpolate 
any $-variables because of the qutoes around 
the EOF marker 
EOF 

echo ------- 

cat <<EOF 
hello $$ 
I'm a here document that does interpolate 
EOF 

echo ------- 

cat <<x 
It doesn't matter what you use as the end of file marker 
x 

echo ------- 

cat <<'x' 
Quotes prevent $-interpolation 
x 

출력 :

hello $$ 
I'm a here document that doesn't interpolate 
any $-variables because of the qutoes around 
the EOF marker 
------- 
hello 29843 
I'm a here document that does interpolate 
------- 
It doesn't matter what you use as the end of file marker 
------- 
Quotes prevent $-interpolation