问从左侧提取文件字符串，但从右起跟随第二个分隔符

EN

awk 'BEGIN{FS=OFS="."} {$(NF-1)=$NF="";sub(/\.+$/,"")} 1' Input_file

awk -F'.' '{for(i=(NF-1);i<=NF;i++){$i=""};sub(/\.+$/,"")} 1' OFS="."  Input_file

awk 'BEGIN{FS=OFS="."} {for(i=(NF-1);i<=NF;i++){$i=""};sub(/\.+$/,"")} 1' Input_file

awk '
BEGIN{                     ##Mentioning BEGIN section of awk program here.
  FS=OFS="."               ##Setting FS and OFS variables for awk to DOT here as per OPs sample Input_file.
}                          ##Closing BEGIN section here.
{
  for(i=(NF-1);i<=NF;i++){ ##Starting for loop from i value from (NF-1) to NF for all lines.
    $i=""                  ##Setting value if respective field to NULL.
  }                        ##Closing for loop block here.
  sub(/\.+$/,"")           ##Substituting all DOTs till end of line with NULL in current line.
}
1                          ##Mentioning 1 here to print edited/non-edited current line here.
'  Input_file              ##Mentioning Input_file name here.

$ awk -F. -v OFS=. '{NF-=2} 1' ip.txt
qwertyuiop.abcdefgh
qwertyuiop

$ perl -F'\.' -lane 'print join ".", @F[0..$#F-2]' ip.txt
qwertyuiop.abcdefgh
qwertyuiop

$ sed 's/\.[^.]*\.[^.]*$//' ip.txt
qwertyuiop.abcdefgh
qwertyuiop