Exercises

1:	Write a sed command that copies a file to standard output, removing all lines that begin with the word Today.
2:	Write a sed command that copies only those lines of a file that begin with the word Today to standard output.
3:	Write a sed command that copies a file to standard output, removing all blank lines (lines with no characters on them).
4:	Write a sed program named ins that copies a file to standard output, changing all occurrences of cat to dog and preceding each modified line with a line that says following line is modified.
5:	Write a sed program named div that copies a file to standard output, copies the first five lines to a file named first, and copies the rest of the file to a file named last.
6:	Write a sed command that copies a file to standard output, replacing a single SPACE as the first character on a line with a 0 (zero) only if the SPACE is immediately followed by a number (0 9). For example: abc abc abc abc 85c 085c 55b 55b 000 0000
7:	How can you use sed to triple-space (i.e., add two blank lines after each line in) a file?