How to pass variables to a HEREDOC in bash?

16

3

I want to do something like this:

$ NAME=John
$ cat << '==end' > test
My name is $NAME
==end

$ cat test
My name is John

Any ideas?

ChocoDeveloper

Posted 2012-08-02T07:16:32.543

Reputation: 2 327

Answers

24

cat <<EOF > test
My name is $NAME
EOF

or even

cat <<==end > test
My name is $NAME
==end

Worked for me.

Looks like when you take ==end in the ' variable doesn't substitute.

ah, here it is in the man page (look 3.6.6):

The format of here-documents is:

      <<[-]word
              here-document
      delimiter

No parameter expansion, command substitution, arithmetic expansion, or pathname expansion is performed on word. If any characters in word are quoted, the delimiter is the result of quote removal on word, and the lines in the here-document are not expanded. If word is unquoted, all lines of the here-document are subjected to parameter expansion, command substitution, and arithmetic expansion. [...]

rush

Posted 2012-08-02T07:16:32.543

Reputation: 957

You can also use double-quotes (cat << "==end" > test), but hard-quotes prevent substitution indeed. – Mat – 2012-08-02T07:31:03.717