Replace multiple patterns, but not with the same string

Question

is it possible to change multiply patterns to different values at the same command? lets say I have

A B C D ABC

and I want to change every A to 1 every B to 2 and every C to 3

so the output will be

1 2 3 D 123

since I have 3 patterns to change I would like to avoid substitute them separately. I thought there would be something like

sed -r s/'(A|B|C)'/(1|2|3)/ 

but of course this just replace A or B or C to (1|2|3). I should just mention that my real patterns are more complicated than that...

thank you!

Answer 1

Easy in Perl:

perl -pe '%h = (A => 1, B => 2, C => 3); s/(A|B|C)/$h{$1}/g'

If you use more complex patterns, put the more specific ones before the more general ones in the alternative list. Sorting by length might be enough:

perl -pe 'BEGIN { %h = (A => 1, AA => 2, AAA => 3);
              $re = join "|", sort { length $b <=> length $a } keys %h; }
          s/($re)/$h{$1}/g'

To add word or line boundaries, just change the pattern to

/\b($re)\b/
# or
/^($re)$/
# resp.

Answer 2

Easy in sed:

sed 's/WORD1/NEW_WORD1/g;s/WORD2/NEW_WORD2/g;s/WORD3/NEW_WORD3/g'

You can separate multiple commands on the same line by a ;

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Update

Probably this was too easy. NeronLeVelu pointed out that the above command can lead to unwanted results because the second substitution might even touch results of the first substitution (and so on).

If you care about this you can avoid this side effect with the t command. The t command branches to the end of the script, but only if a substitution did happen:

sed 's/WORD1/NEW_WORD1/g;t;s/WORD2/NEW_WORD2/g;t;s/WORD3/NEW_WORD3/g'