for loop not working in generate html file via bash script

Question

When I am running following bash script-

#!/bin/bash
items="b.js
   a.js
   c.js"
startScript='<script src="'
endScript='"></script>'
for item in $items
do
  echo $startScript$item$endScript
done

Output:

 <script src="c.js"></script>
 <script src="a.js"></script>
 <script src="b.js"></script>

I want to run this for loop inside generated html file via a bash script. For loop is not working here.

#!/bin/bash
items="b.js
   a.js
   c.js"
startScript='<script src="'
endScript='"></script>'
cat << noEcho
<HTML>
<HEAD>
<TITLE>  Bash Script  </TITLE>
</HEAD>
<BODY>
for item in $items
do
 echo $startScript $item $endScript
done
</BODY>
</HTML>
noEcho

Don't store lists in strings -- use arrays for that. files=( b.js a.js c.js ), then for item in "${files[@]}"; ... — Charles Duffy
– Charles Duffy, Commented Sep 16, 2016 at 23:11
First, /bin/sh isn't always bash. Second, how is this not working? Third, I'd prefer printf to echo. Fourth, why bash instead of perl? — Elliott Frisch
– Elliott Frisch, Commented Sep 16, 2016 at 23:11
And you need to use $() if you want to substitute the output of some code into heredoc body text. — Charles Duffy
– Charles Duffy, Commented Sep 16, 2016 at 23:12
Also, you're never assigning anything to $items, so I don't know why you'd expect for item in $items to do anything useful even if you did properly have it inside of a command substitution. — Charles Duffy
– Charles Duffy, Commented Sep 16, 2016 at 23:13
@CharlesDuffy if I am using array getting Syntax error: "(" unexpected and for this "${files[@]}" -- Bad substitution — user2194838
– user2194838, Commented Sep 16, 2016 at 23:16

Charles Duffy · Accepted Answer · 2016-09-16 23:21:18Z

3

Simple example with the most glaring bugs fixed:

#!/bin/bash
files=( b.js a.js c.js)
startScript='<script src="'
endScript='"></script>'
cat << noEcho
<html><head><title>Bash Script</title></head><body>
$(
for file in "${files[@]}"; do
 echo "${startScript}${file}${endScript}"
done
)
</body></html>
noEcho

You can see the above running, with its output, at http://ideone.com/rSsO9H.

Some notes:

Don't do this. Really. Use a real template language that understands HTML syntax and knows how to escape content properly; you'll find securing this kind of code next to impossible if/when dealing with dynamic data.
Strings are not arrays. If you want an array, use an actual array.
If you want the output of a given piece of code to be substituted into a string (or, in this case, a heredoc), it needs to be in a command substitution: $()

edited Sep 16, 2016 at 23:21

answered Sep 16, 2016 at 23:15

Charles Duffy

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