How to replace part of header, remove between two characters bash, awk, sed

Using gnu sed you can use a negated bracket expression:

sed 's/_[^\t]*//g' file

_[^\t]* matches underscore followed by zero or more non-tab characters.

bash unix awk sed

try in awk:

awk '{gsub(/_[^\\]*/,"");print}'   Input_file

try in sed:

sed 's/_[^\\]*//g'   Input_file

EDIT: As OP said \t are the TABs in Input_file so adding following solution too now.

awk '{gsub(/_[^\t]*/,"");print}'  Input_file

bash unix awk sed

sed 's/_[^\t]*\t/\t/g'

if you're not worried about the last field.

sed 's/_[^\t]*\t/\t/g;s/_[^\t]*$//'

otherwise.

CodeHunter