header=$(head -n 1 file) (printf "%s\n" "$header"; sed 1d file|grep -v "^$header$" ) > newfile - grab the header line into a variable
- print the header
- print everything except the first line, and omit lines that look like the header
header=$(head -n 1 file) (printf "%s\n" "$header"; sed 1d file|grep -v "^$header$" ) > newfile