bash nested EOF

[drwg]

I need to write a script with nested EOF's to avoid generating potentially very large numbers of intermediate files and cannot work out how to do this, rough code follows; any ideas greatly appreciated

#!/bin/sh

outer_command <<OUTER_EOF
#!/bin/sh
inner_command <<INNER_EOF
start of inner_script contents
.
.
.
end of inner_script contents
INNER_EOF
OUTER_EOF

[ramin.honary]

First, my opinion is, if you need nested "Here Files", you are almost certainly going about solving your problem the wrong way. Or if you are sure this is the ONLY way to solve the problem, you are better of NOT using bash. Try Perl or Python instead.

However, to answer your question, I would do it like this

#!/bin/bash

cat <<-__SUB_COMMAND0__
Executed within level 0
__SUB_COMMAND0__

bash <<-__LEVEL1__

cat <<-__SUB_COMMAND1__
Executed within level 1
__SUB_COMMAND1__

bash <<-__LEVEL2__

cat <<-__SUB_COMMAND2__
Executed within level 2
__SUB_COMMAND2__

__LEVEL2__
__LEVEL1__

What this does is creates a child bash process with the input of the child process coming from the "Here File". Once you have established the bash sub-process, you can "cat" information to sub-sub-processes like grep or whatever.

However, as you can see, this quickly turns into spaghetti code and is very difficult to read and debug.