bash multiple heredocs et al

Question

I have a bash build script that I (well, Jenkins, but that's immaterial, this is a bash question) executes like this:

sudo -u buildmaster bash <<'END'
# do all sorts of crazy stuff here including using variables, like:
ARGS=something
ARGS="$ARGS or other"
# and so forth
END

Now I'd like to pass in a variable (Jenkins parameterized build), say PLATFORM. The trouble is that if I refer to $PLATFORM in my heredoc, it is undefined (I used 'END' to avoid variable substitution). If I turn the 'END' into END, my scripts becomes really unreadable with all the escapes I need to use.

So the question is, is there some (easy, readable) way of passing in two heredocs, one with quotes, and one without, into the same bash invocation? I was looking for something like this

sudo -u buildmaster bash <<PREFIX <<'END'
PLATFORM=$PLATFORM
PREFIX
# previous heredoc goes here
END

in the hope that it would simply concatenate, but I can't get the two heredocs to work (I guess bash is not Perl)

My fallback plan is to create temp files, but I was hoping there's a trick I don't know and that somebody could teach me :-)

Answer 1

In this case you could consider using bash with its -s argument:

sudo -u buildmaster bash -s -- "$PARAMETER" <<'END'
# do all sorts of crazy stuff here including using variables, like:
ARGS=something
ARGS="$ARGS or other"
# and so forth
PARAMETER=$1
END

(note that you have a syntax error, your closing END is quoted and shouldn't be).

---

There's another possibility (so that you have lots of options—and this one might be the simplest, if it applies) is to have your variables exported, and use the -E switch to sudo that exports the environment, e.g.,

export PARAMETER
sudo -E -u buildmaster bash <<'EOF'
# do all sorts of crazy stuff here including using variables, like:
ARGS=something
ARGS="$ARGS or other"
# and so forth
# you can use PARAMETER here, it's fine!
EOF

Along these lines, if you don't want to export everything, you may use env as follows:

sudo -u buildmaster env PARAMETER="$PARAMETER" bash <<'EOF'
# do all sorts of crazy stuff here including using variables, like:
ARGS=something
ARGS="$ARGS or other"
# and so forth
# you can use PARAMETER here, it's fine!
EOF