Example: file contains the following:

lebnassvm0a-dr      test1      /vol/test1
lebnassvm0a-dr      test2      /test2
lebnassvm0a-dr      test3      /test3
stgtestsvm1-dr      test21      /test21
stgtestsvm1-dr      test22      /test22
stgtestsvm1-dr      test23      /test23

I want to find the "-dr" and replace with "-drt" and insert the full string in front of the existing, like this:

lebnassvm0a-drt lebnassvm0a-dr      test1      /vol/test1
lebnassvm0a-drt lebnassvm0a-dr      test2      /test2
lebnassvm0a-drt lebnassvm0a-dr      test3      /test3
stgtestsvm1-drt stgtestsvm1-dr      test21      /test21
stgtestsvm1-drt stgtestsvm1-dr      test22      /test22
stgtestsvm1-drt stgtestsvm1-dr      test23      /test23

Example: file contains the following:

lebnassvm0a-dr      test1      /vol/test1
lebnassvm0a-dr      test2      /test2
lebnassvm0a-dr      test3      /test3
stgtestsvm1-dr      test21      /test21
stgtestsvm1-dr      test22      /test22
stgtestsvm1-dr      test23      /test23

I want to find the "-dr" and replace with "-drt" and insert the full string in front of the existing, like this:

lebnassvm0a-drt lebnassvm0a-dr      test1      /vol/test1
lebnassvm0a-drt lebnassvm0a-dr      test2      /test2
lebnassvm0a-drt lebnassvm0a-dr      test3      /test3
stgtestsvm1-drt stgtestsvm1-dr      test21      /test21
stgtestsvm1-drt stgtestsvm1-dr      test22      /test22
stgtestsvm1-drt stgtestsvm1-dr      test23      /test23

• sed

• Do you already know how to replace -dr with -drt? – Ulrich Eckhardt Commented Nov 19, 2024 at 15:24
• Replacing the -dr with -drt is easy. the part i'm not sure about is inserting the replaced full string with the changed substring. – Bob Moore Commented Nov 19, 2024 at 15:27
• If you can ever have a first field that does not end with -dr then you should include that in your sample input/output so we can see how that should be handled. – Ed Morton Commented Nov 21, 2024 at 11:23

3 Answers 3

What I would do:

$ sed -E 's/^([^-]+-dr)/\1t \1/' file
lebnassvm0a-drt lebnassvm0a-dr      test1      /vol/test1
lebnassvm0a-drt lebnassvm0a-dr      test2      /test2
lebnassvm0a-drt lebnassvm0a-dr      test3      /test3
stgtestsvm1-drt stgtestsvm1-dr      test21      /test21
stgtestsvm1-drt stgtestsvm1-dr      test22      /test22
stgtestsvm1-drt stgtestsvm1-dr      test23      /test23

The regular expression matches as follows:

This might work for you (GNU sed):

sed 's/^\S*-dr\>/&t &/' file

Replace the first non-white spaced string ending in -dr with itself followed by a t a space and the original string.

Using any awk:

$ awk '{print $1"t", $0}' file
lebnassvm0a-drt lebnassvm0a-dr      test1      /vol/test1
lebnassvm0a-drt lebnassvm0a-dr      test2      /test2
lebnassvm0a-drt lebnassvm0a-dr      test3      /test3
stgtestsvm1-drt stgtestsvm1-dr      test21      /test21
stgtestsvm1-drt stgtestsvm1-dr      test22      /test22
stgtestsvm1-drt stgtestsvm1-dr      test23      /test23

or GNU sed:

$ sed -E 's/\S+/&t &/' file
lebnassvm0a-drt lebnassvm0a-dr      test1      /vol/test1
lebnassvm0a-drt lebnassvm0a-dr      test2      /test2
lebnassvm0a-drt lebnassvm0a-dr      test3      /test3
stgtestsvm1-drt stgtestsvm1-dr      test21      /test21
stgtestsvm1-drt stgtestsvm1-dr      test22      /test22
stgtestsvm1-drt stgtestsvm1-dr      test23      /test23

The above assume given the example provided in the question that you really just want to duplicate and add t to the first field in the input, the requirement to match on -dr is a red herring.