bash: How to modify a string within a field

Question

I have the following lines:

field1    1-23_4_5    field3
field1    2-40_5_7    field3
field1    3-43_7_9    field3
             .
             .
             .  

I would like to modify the second field so that

1-23_4_5 becomes 1-23

I am thinking the combination of awk and cut would do the trick. Is there a simple way to go about this?

Thank you so much for your help in advance.

Answer 1

Through awk,

$ awk 'sub(/_[^_]*_[^_]*$/,"",$2)1' file
field1 1-23 field3
field1 2-40 field3
field1 3-43 field3

Through sed,

$ sed 's/^\([^ ]\+\ *[^_]\+\)[^ ]\+/\1/g' file
field1    1-23    field3
field1    2-40    field3
field1    3-43    field3