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Shell Programming and Scripting

Modify capture group

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# 1  
Old 07-21-2016
Modify capture group
Hi, is it possible to modify captured group in substitution, e.g. to output \1 in 2 columns, first one unchanged and 2nd one change to upper case + replace - with underscore. I only did the first part:

Code:
s/\(a.*\)/\1 \L\1/g

Can i do the replacement in the same command?

Thanks a lot.

Moderator's Comments:
Mod Comment Please use code tags
Last edited by jim mcnamara; 07-21-2016 at 01:27 PM..
# 2  
Old 07-21-2016
The & character references the unchanged text that matches the pattern.

so If I get what you want:
Code:
s/\(a.*\)/\1 \L\1/g -> s/\(a.*\)/\1 \L\1/_&/g

But I'm not clear on what you mean by the second one versus the first one. So the example could be wrong.

Please give an example of sample input and expected output. Thanks.
# 3  
Old 07-21-2016
I'm afraid that can't be done, not even with a second substituition, as the start of the upper case replacement string can't be retrieved reliably and consistently.
# 4  
Old 07-21-2016
That is what I wondered, but I though he wanted the original with a prepended '_'
character.
e.g.:
Code:
a.foo -> A.FOO _a.foo

Since we have no answer we cannot know.
# 5  
Old 07-22-2016
Thanks to all of you. I intend to do something like:

abc-efg -> abc-efg ABC_EFG

Just wonder if this can be done in the same sed script.

Thanks again.



Moderator's Comments:
Mod Comment Please use (i)code tags as required by forum rules!
Last edited by RudiC; 07-22-2016 at 12:35 PM.. Reason: Added icode tags.
# 6  
Old 07-22-2016
This cannot be generalised; it won't handle multiple dashes, it will fail on input with different structure, it's ugly:
Code:
echo abc-efg | sed 's/\([a-z]\+\)\(-*\)\([a-z]\+\)/\1\2\3 \U\1_\3/g'
abc-efg ABC_EFG

# 7  
Old 07-25-2016
There will be multiple dashes at various locations... Seems i've to do one more pipe.

Thanks a lot.
Rgds
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