Bash Sed replace - bash

Question

I'm working in a Zend CRUD generator and I have to replace the word "test" which is in $targetForm file with the form code of each field.
field[0]="foo"
field[1]="bar"
textareafield='$'"acme_en = new Utils_Form_Element_Textarea('acme_en',array('langblock'=>'en', 'isWysiwyg' => true));
"'$'"this->addElement("'$'"acme_en);
"'$'"this->addElement('textarea','acme_fr', array( 'label'=>__('acme'), 'langblock'=>'fr', 'isWysiwyg' => true, 'altLangElem' => "'$'"acme_en));"
for ((i=0; i<${#field[#]}; i++));
do
formfield[$i]=$textareafield
formfield[$i]=${formfield[$i]//acme/${field[$i]}}
echo ${formfield[$i]}
sed -i "s/test/test\n ${formfield[$i]}/" $targetForm
done
The command line says:
$foo_en = new Utils_Form_Element_Textarea('foo_en', array('langblock'=>'en', 'isWysiwyg' => true)); $this->addElement($foo_en); $this->addElement('textarea','foo_fr', array( 'label'=>__('foo'), 'langblock'=>'fr', 'isWysiwyg' => true, 'altLangElem' => $foo_en));
sed: -e expression #1, char 120: unterminated `s' command
$bar_en = new Utils_Form_Element_Textarea('bar_en', array('langblock'=>'en', 'isWysiwyg' => true)); $this->addElement($bar_en); $this->addElement('textarea','bar_fr', array( 'label'=>__('bar'), 'langblock'=>'fr', 'isWysiwyg' => true, 'altLangElem' => $bar_en));
sed: -e expression #1, char 120: unterminated `s' command
Maybe there's a problem with the specials character but I don't know how to solve it.

Answer 1

This error you get very likely has nothing to do with using \n in sed substitution (especially since you mentioned in the comments that you are using GNU sed version 4.2.1).
The real culprit is textareafield which contains a multi-line string.
What happens is that when ${formfield[$i]} gets expanded, your sed command looks like this
sed -i "s/test/test\n line1
line2
line3/"
This is problematic because without terminating lines with a literal \, sed would interpret each line as a complete command in itself, in this case
s/test/test\n line1
which is missing a / at the end, hence the error "unterminated `s' command".
To fix this, what we want is to insert a \ to the end of every line except the last, i.e.
sed -i "s/test/test\n line1\
line2\
line3/"
I got your example to work by adding two lines
for ((i=0; i<${#field[#]}; i++));
do
formfield[$i]=$textareafield
formfield[$i]=${formfield[$i]//acme/${field[$i]}}
formfield[$i]=${formfield[$i]//\;/\;\\}
formfield[$i]=${formfield[$i]%\\}
echo ${formfield[$i]}
sed -i "s/test/test\n ${formfield[$i]}/" $targetForm
done
Since all the lines in textareafield end in ;, I replaced all ; with ;\, then removed the last \ from the last line.

Answer 2

sed does not support \n in the substitution, but you can use a literal newline if you escape it. Also, you need to quote the ' characters. Here is one way of doing it:
for ((i=0; i<${#field[#]}; i++));
do
formfield[$i]=$textareafield
formfield[$i]=${formfield[$i]//acme/${field[$i]}}
sedexpr="${formfield[$i]}"
sedexpr="${sedexpr//\'/\'}"
sedexpr="${sedexpr//
/\\
}"
sed -i "s/test/test\
${sedexpr}/" $targetForm
done
But at this level of complexity you're probably better off switching to something like Python.