Insert content into template file using bash

Question

I have a template file I want to copy and then edit from a script, inserting content at specific template points. For example, my template file might be something like,

...
rm -rf SomeDirectory
make install
#{INSERT-CONTENT-HERE}
do-something-else
...

In another script, I want to add content at "#{INSERT-CONTENT-HERE}" within a loop, i.e.

for i in c; do
  # Write content to the template file copy at the correct point.
done

I think sed is the right tool, but I'm not familiar enough to know the syntax, and the man page isn't helping.

Thanks for the update, and good luck. Do you also have a question? — Kerrek SB
– Kerrek SB, Commented Mar 19, 2012 at 20:28
For those with IQDCS (Inferred Question Discernment Challenge Syndrome), the question is, "What would be the correct command to do this?" — Dave Mateer
– Dave Mateer, Commented Mar 19, 2012 at 20:32
what sort of thing are you iterating in the for loop? the content you want to replace? other copies of the templates? — Elias Dorneles
– Elias Dorneles, Commented Mar 19, 2012 at 20:33
@eljunior: Right now, it is a series of RPM spec file commands based on a bunch of files. The loop gets the file names across certain directories meeting certain requirements, applies some transformation logic, and builds the string command. That command needs to be inserted into the template, once for each file. — Dave Mateer
– Dave Mateer, Commented Mar 19, 2012 at 20:36

perreal · Accepted Answer · 2012-03-19 20:45:43Z

1

An example:

echo "Line #{INSERT-CONTENT-HERE}" | sed 's/#{INSERT-CONTENT-HERE}/---/'

To modify a file:

sed -i 's/#{INSERT-CONTENT-HERE}/---#{INSERT-CONTENT-HERE}/' filename

where -i means in-place edit so be warned

if you do:

sed -i.bak 's/#{INSERT-CONTENT-HERE}/---/' filename

it should back up original as filename.bak

also to make multiple substitutions at each line use the g flag:

sed -i.bak 's/#{INSERT-CONTENT-HERE}/---/g' filename

edited Mar 19, 2012 at 20:45

answered Mar 19, 2012 at 20:28

perreal

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3 Comments

Dave Mateer Over a year ago

Am I mistaken, or would that only get me past the first iteration of the loop? (After which the marker is gone.) Also, I don't want to have to regex-escape the replacement text if possible. Would that be necessary in your solution?

perreal Over a year ago

@DaveMateer, this should be enough to do what you want (here filename is the template). You don't need to escape the replacement text (mostly I guess).

perreal Over a year ago

look at the second example, you can move the marker as long as you have additions.

Dave Mateer · Accepted Answer · 2012-03-19 21:04:53Z

1

You can copy the output of all the commands into a temporary file and then copy the contents of that entire file into the template file:

TEMPFILE=`mktemp` && (
  for i in c
    echo "SomeTextBasedOn $i" >> $TEMPFILE
  done
  sed -i '/{INSERT-CONTENT-HERE}/r '$TEMPFILE targetfile
  rm $TEMPFILE
)

answered Mar 19, 2012 at 21:04

Dave Mateer

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