sed / awk - remove all but a specific matching pattern from a file

I want to convert a makefile like this:

test.o: var_one.h var_two.h

test2.o: another_header.h var_three.h archive/something_random.h

to this:

test.o: var_one.h var_two.h

test2.o: var_three.h

ie, I want to remove any filename that doesn't 开发者_如何学Pythonstart with the search string "var_"

I can't seem to find a lot of information for sed about pattern matching when not wanting the search string?

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You really need awk for this type of job. With sed, attempting to remove words that don't match a string would be a painful (and probably ugly) script to write.

awk '{for(i=2;i<=NF;i++)$i !~ /var_.*\.h/ && $i=""}1' Makefile

Input

$ cat Makefile
test.o: var_one.h var_two.h

test2.o: another_header.h var_three.h archive/something_random.h

Output

$ awk '{for(i=2;i<=NF;i++)$i !~ /var_.*\.h/ && $i=""}1' Makefile
test.o: var_one.h var_two.h

test2.o:  var_three.h