Не могли бы вы попробовать следующее.
awk 'BEGIN{FS=OFS=","} {sub(/^N/,"",$4);sub(/^E/,"",$5)} 1' Input_file
Если OP хочет заменить любую букву (не только N или E), то попробуйте выполнить следующее.
awk 'BEGIN{FS=OFS=","} {sub(/^[[:alpha:]]/,"",$4);sub(/^[[:alpha:]]/,"",$5)} 1' Input_file
ИЛИ
awk 'BEGIN{FS=OFS=","} {sub(/^./,"",$4);sub(/^./,"",$5)} 1' Input_file
Объяснение: Добавление подробного объяснения приведенного выше кода здесь.
awk ' ##Starting awk program from here.
BEGIN{ ##Starting BEGIN section of this awk program from here.
FS=OFS="," ##Setting field separator and output field separator as comma here.
}
{
sub(/^N/,"",$4) ##Using substitute function of awk to substitute starting N in column 4th here.
sub(/^E/,"",$5) ##Using substitute function of awk to substitute starting N in column 5th here.
}
1 ##Mentioning 1 will print edited/non-edited line here.
' Input_file ##Mentioning Input_file name here.