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I have this a script containing a function and a function call. Inside the function there's an heredocument:

#!/bin/bash

DWA() {
    ......
    mysql -u root -p <<-MYSQL
        ......
    MYSQL
}
DWA

The problem

The execution breaks with an error regarding heredocument delimiter (likely, due to the delimiter MYSQL being indented).

The problem didn't happen when I removed all leads (whitespaces/tabs).

My question

Given functions strip all leading tabs (I don't know about other types of leads, like whitespaces), why do I encounter this problem and what, if at all, can be done against that?

  • 2
    Functions strip all leads? – Jesse_b Dec 2 '17 at 23:35
  • I've read in the past that they are, or I was confused with something else. – Arcticooling Dec 2 '17 at 23:39
  • 2
    Are you sure you're indenting with tabs and not with spaces? – igal Dec 2 '17 at 23:40
  • @Arcticooling, I don't think I have ever heard anything like that however there is a lot I haven't heard about. I think it's likely whatever you read does not apply in this case. Here docs are sort of a special block of it's own, and as far as I know they require your ending delimiter to be at the beginning of the line with no leading whitespace. – Jesse_b Dec 2 '17 at 23:45
  • I don't understand. I didn't ask why you're indenting. I just asked if you're sure that you're using tabs. – igal Dec 2 '17 at 23:57
2

You're probably not indenting your heredoc with tabs. Every line of the heredoc must be indented with a tab, including the first line (where the delimiter is introduced). Here is a test case for you:

echo -e 'function heredoc() {\n\tcat <<-HEREDOC\n\t\tThis is a test\tHEREDOC\n} heredoc' > heredoc.sh

Try running that command and then running heredoc.sh. You should get the following output:

This is a test.

Alternatively, here is the same script but with the first line indented with spaces instead of a tab:

    echo -e 'function heredoc() {\n    cat <<-HEREDOC\n\t\tThis is a test\tHEREDOC\n} heredoc' > heredoc2.sh

If we run heredoc2.sh we get the following error output:

bash heredoc2.sh 
heredoc2.sh: line 4: warning: here-document at line 2 delimited by end-of-file (wanted `HEREDOC')
heredoc2.sh: line 5: syntax error: unexpected end of file

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