How to make long SED script leaner and more readable as code

Question

Here is the sed part of my script right now:

sed -i -e 's/<Codec>/<inm:Video-codec>/g;s/<Duration_String4>/<inm:D-Duration>/g;s/<Width>/<inm:Width>/g;s/<\/Codec>/<\/inm:Video-codec>/g;s/<\/Duration_String4>/<\/inm:D-Duration>/g;s/<\/Width>/<\/inm:Width>/g;s/<FileExtension>/<inm:Wrapper>/g;s/<\/FileExtension>/<\/inm:Wrapper>/g' "$1"

It's only going to get longer and longer. Is there a way to make this more readable as a piece of code? Can I have a new line for each replacement, or must I start a new sed command in order to do that?

Answer 1

First setup the sedstring in parts:

SEDSTR='s/<Codec>/<inm:Video-codec>/g'
SEDSTR="$SEDSTR;"'s/<Duration_String4>/<inm:D-Duration>/g'
SEDSTR="$SEDSTR;"'s/<Width>/<inm:Width>/g'
SEDSTR="$SEDSTR;"'s/<\/Codec>/<\/inm:Video-codec>/g'
SEDSTR="$SEDSTR;"'s/<\/Duration_String4>/<\/inm:D-Duration>/g'
SEDSTR="$SEDSTR;"'s/<\/Width>/<\/inm:Width>/g'
SEDSTR="$SEDSTR;"'s/<FileExtension>/<inm:Wrapper>/g'
SEDSTR="$SEDSTR;"'s/<\/FileExtension>/<\/inm:Wrapper>/g'

sed -i -e "$SEDSTR" "$1"

EDIT 1: Remark: Using shell-variables in lowercase is better. EDIT 2: Appending can be done with +=

sedstr='s/<Codec>/<inm:Video-codec>/g'
sedstr+=';s/<Duration_String4>/<inm:D-Duration>/g'
sedstr+=';s/<Width>/<inm:Width>/g'
sedstr+=';s/<\/Codec>/<\/inm:Video-codec>/g'
sedstr+=';s/<\/Duration_String4>/<\/inm:D-Duration>/g'
sedstr+=';s/<\/Width>/<\/inm:Width>/g'
sedstr+=';s/<FileExtension>/<inm:Wrapper>/g'
sedstr+=';s/<\/FileExtension>/<\/inm:Wrapper>/g'

sed -i -e "${sedstr}" "$1"

Your next step might be making a function that will parse a configfile.
The configfile could have lines like

<Codec>*<inm:Video-codec>
</Codec>*</inm:Video-codec>

(with * a nice FieldSep) and let your function take care of the backslashes.

Or even better: tell your function is should always add an end-tag replacement, and make a config file like

Codec/inm:Video-codec
Duration_String4/inm:D-Duration
Width/inm:Width
FileExtension/inm:Wrapper