Multline Bash Variable Replacement

I’ve recently needed to append several lines of data to a SAS data step that I collected and built via a shell script. For search-and-replace in bash I typically use sed, but this time I ran into a problem - sed does not like multiline shell variables. Thanks to Stack, I found a way to accomplish this task using awk instead.

Suppose you have a file called data.sas with the following contents:

data person;
   infile datalines delimiter=','; 
   input name :$10. dept :$30.;
   datalines4;                      
John,Sales
Mary,Accounting
Theresa,Management
Stewart,HR
;;;;
run;

Note that I am using a datalines4 statement so that I get an easy to identify target for the substitution. I want to insert a multiline shell variable before the ;;;; to add my data to this data step. Say I have the following variable:

NEWDATA=$(cat <<-END
Will,Compliance
Sidney,Management
END
)

If I try to use sed (sed "s/\;\{4\}/$DATA\n;;;;/" data.sas) I will get an error about an unterminated s command. Instead of sed, I can use awk with a variable to achieve the same goal:

awk -v r="$NEWDATA\n;;;;" '{gsub(/;{4}/, r)}1' data.sas

The one downside is that awk does not have an in-place option like sed, and if I try to redirect to the same file I’m reading from I get an empty file out. So you’ll have to rename the original file in your processing script to achieve a similar effect as with the inplace option in sed.

For additional approaches, see this StackOverflow Question.