Try the following ....
But the code is tested with 5 chars as criterion instead of 75.
Change as per your requirement.
Code:
awk '{
if ( length($0) > 5 )
{
str=$0 ;
i=0 ;
while(length(str) > 5)
{
printf("%s\n",substr($0,i+1,5) );
i+=5 ;
str=substr($0,i,length($0) );
}
if( length(str) > 1 )
printf("%s\n", substr(str,2,length(str))) ;
}
else
{
print $0
}
}' file1
