Related: remove left columns from text file
Old Fortran or COBOL programs may have columns 73-80 filled with vestigial card sequence numbers. Remove them or any other text more than N columns long by:
Trim right columns
This example keeps the first 72 columns of text from “ancient.for” on each row, resaving as “ancient.f”.
cut -c-72 > ancient.f < ancient.for
Any trailing whitespace (up to 72 characters for this example) remains.