How do you append to a variable string in a script?

Question

How do I append a string that has variables in it?

sed 's/MIMG109AL1ARP\t[[:alnum:]]*\t/ /g'

I initially thought sed, but I don't want to replace anything, I want to add something after the intial line.

Some example strings are as follows:

MIMG109AL1ARP     PQHDO0542I7537

MIMG109AL1ARP     PQHDO0372I2435

MIMG109AL1LLL     QRHDO0382I2342

MIMG109AL1LLL     PQHDO362I2345

However I want them to look like this:

MIMG109AL1ARP     PQHDO0542I7537     appendagehere

MIMG109AL1ARP     PQHDO0372I2435     appendagehere

MIMG109AL1LLL     QRHDO0382I2342     appendage2here

MIMG109AL1LLL     PQHDO362I2345      appendage2here

Just edited the file to make my question more clear! I need to append separate lines separately, not every line. Thank you for your input so far. Any help or redirection is appreciated!

Answer 1

In sed, $ represents the end of the line. So you can say

sed -e 's/$/\twhatever/'

If you want to append only to non-empty lines, but leave empty lines empty, then use the following (where & in sed is the matched string, which in this case is one character):

sed -e 's/.$/&\twhatever/'

Or you can also just only do the substitution on non-empty lines:

sed -e '/./s/$/\twhatever/'

Answer 2

With some help from one of my friends, I was able to get it to work using this line!

sed 's/\(MIMG109AL1ARP..*\)\($\)/\1\twhatIwant\2/g'

The solution was to break up the expression into two sub expressions. Instead of changing what I already had, I was able to flank what I wanted between the two sub-expressions.

Thank you both for posting and trying to help me out.

Answer 3

With only 9 different patterns and appendages to deal with, try something like this:

#! /usr/bin/perl

use strict;

my %append = ( # matchregex       => appendstring
               qr/^MIMG109AL1ARP/ => 'appendagehere',
               qr/^MIMG109AL1LLL/ => 'appendage2here',
               # more here
             );

while (<>) {
   chomp;
   foreach my $re (keys %append) {
       if (m/$re/) {
           s/$/\t$append{$re}/;
           last;
       }
   }
   print $_, "\n";
}