Join multiple sed commands in one script for processing CSV file

First of all, as Michael showed, you can just combine all of these into a single command:

sed '/^FOOTER/d; s/^\"//; s/\"$//; s/\"|\"/|/g' csv > csv1

I think some sed implementations can't cope with that and might need:

  sed -e '/^FOOTER/d' -e 's/^\"//' -e 's/\"$//' -e 's/\"|\"/|/g' csv > csv1

That said, it looks like your fields are defined by | and you just want to remove " around the entire field, leaving those that are within the field. In that case, you could do:

$ sed '/FOOTER/d; s/\(^\||\)"/\1/g; s/"\($\||\)/\1/g' csv 
HEADER
first, column|second "some random quotes" column|third ol' column

Or, with GNU sed:

sed -r '/FOOTER/d; s/(^|\|)"/\1/g; s/"($|\|)/\1/g' csv 

You could also use Perl:

$ perl -F"|" -lane 'next if /FOOTER/; s/^"|"$// for @F; print @F' csv 
HEADER
first, column|second some random quotes column|third ol' column

This would also work:

sed 's/^"//; s/"|"/|/g; s/""$/"/'

Example:

$ echo '"this"|" and "ths""|" and "|" this 2"|" also "this", "thi", "and th""' | 
sed 's/^"//; s/"|"/|/g; s/""$/"/'
this| and "ths"| and | this 2| also "this", "thi", "and th"

pretty version

sed '
s/^"//
s/"|"/|/g
s/""$/"/
$d
'