here-strings-and-here-documents.md

Here Strings 与 Here Documents

Here Strings

[n]<<< word

Here Documents

[n]<<[-]delimiter
here-document
delimiter

delimiter 可以是 EOF 或者其他任意字符。

例子

cat <<EOF > file.txt
hello
world
$PATH
EOF

<<-

If the redirection operator is ‘<<-’, then all leading tab characters are stripped from input lines and the line containing delimiter. This allows here-documents within shell scripts to be indented in a natural fashion.

避免符号替换

默认 here-document 会执行 $var 和 $() shell 的语法替换，只有在 delimiter 两边加上单括号可以防止替换。

[n]<<[-]'delimiter'
  here-document
delimiter

例子

cat <<'EOF' > file.txt
hello
world
$PATH
EOF

参考 Here Documents 的文档，或者 https://stackoverflow.com/a/22698106/4622308