I need to remove everything before and after a name in bash script, the following are examples

test_3123_123_testone-2.cpp
abc_3123_12312_a.cpp
johnchase_4123123123_123123123_johnc-1.cpp

I would need them simply change into

testone.cpp
a.cpp
johnc.cpp

But having trouble with regex and trying to get this setup properly, any advice would be great!

CodePudding user response：

the text right before .cpp but ignoring any dashes(-2) if they exist behind it.

Do exactly that. Write it from the end.

• "before .cpp" -> so .cpp must be last
• "ignoring any dashes" - so there is a dash(-2)
  • "if they exist behind it" - the dash is optional
• "the text" - so match the text.

var=test_3123_123_testone-2.cpp
[[ "$var" =~ ([^_-]*)(-[0-9] )?.cpp$ ]]
echo ${BASH_REMATCH[1]}.cpp

CodePudding user response：

If your filename is in a variable called file, then: echo ${${file##*_}/-[0-9]*[.]/.}.

Breaking that down, inside out:

• ${file$$*_} remove everything from start of string to last _
• ${file/-[0-9]*[.]/.} replace "dash number dot" with just a dot

This is not bullet-proof, but it covers the given cases.

$ for file in test_3123_123_testone-2.cpp abc_3123_12312_a.cpp johnchase_4123123123_123123123_johnc-1.cpp
do
  echo ${${file##*_}/-[0-9]*[.]/.}
done
testone.cpp
a.cpp
johnc.cpp