Forwarding from Debian #1037195:
bullseye (0.5.11+git20200708+dd9ef66-5),
sid (0.5.12-2) and
git (b00288fd28c1b39d0f1531b6e6d86de59de4be8d)
dash observe the following:
$ cat -n boment
1 echo "$(head -n1 <<EOF)"
2 # 2
3 # 3
4 EOF
$ sh boment
boment: 4: EOF: not found
$ sh -x boment
+ head -n1
+ echo
+ EOF
boment: 4: EOF: not found
$
This agrees with bullseye bash (5.1-2+deb11u1) but not sid bash
(5.2.15-2+b2), which outputs "# 2" (and a warning);
I believe that bash is correct here (sans the warning).
POSIX Issue 7, XCU, 2. Shell Command Language says
2.7.4 Here-Document
The redirection operators "<<" and "<<-" both allow redirection of subsequent lines read by the shell to the input of a command. The redirected lines are known as a "here-document".
The here-document shall be treated as a single word that begins after the next <newline> and continues until there is a line containing only the delimiter and a <newline>, with no <blank> characters in between. Then the next here-document starts, if there is one. The format is as follows:
and its counterpart in Issue 8 Draft 3
80601 2.7.4 Here-Document
80602 The redirection operators "<<" and "<<-" both allow redirection of subsequent lines read by
80603 the shell to the input of a command. The redirected lines are known as a ``here-document’’.
80604 The here-document shall be treated as a single word that begins after the next NEWLINE token
80605 and continues until there is a line containing only the delimiter and a <newline>, with no
80606 <blank> characters in between. Then the next here-document starts, if there is one. For the
80607 purposes of locating this terminating line, the end of a command_string operand (see sh) shall be
80608 treated as a <newline> character, and the end of the commands string in $(commands) and
80609 `commands` may be treated as a <newline>. If the end of input is reached without finding the
80610 terminating line, the shell should, but need not, treat this as a redirection error. The format is as
80611 follows:
That is, as I understand it:
echo "$(head -n1 <<EOF
abc
def
EOF
)"
and
echo "$(head -n1 <<EOF)"
abc
def
EOF
are always required to work, and Issue 8 allows shells to have
echo "$(head -n1 <<EOF
abc
def
EOF)"
work as well.
Either way, this looks to me like a POSIX violation?
Best,
наб
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