Delete the first five characters on any line of a text file in Linux with sed
Use cut:
cut -c6-
This prints each line of the input starting at column 6 (the first column is 1).
sed 's/^.....//'
means
replace ("s", substitute) beginning-of-line then 5 characters (".") with nothing.
There are more compact or flexible ways to write this using sed or cut.
sed 's/^.\{,5\}//' file.dat
awk '{print substr($0,6)}' file