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#print You can now change a line of a file by a slow procedure: delete the old version and insert the new one. For example, you could replace line 4 of a file with 4d 3a new version of line

#print So far you only know how to copy and print existing files in the editor, and not how to get started from scratch. The 'a' (append) command lets you type in new text. For example, the sequence

#print Using the "^" character, you can easily put things at the beginnings of lines. For example s/^/***/ puts "***" at the beginning of the line. Now edit the file "text" and put the symbol '='

#print You can also use relative addresses of the +1 or -1 sort with context searches. For example, to print the line after the line containing "cat", you could say /cat/+1p Here is a file "text"

#print A very useful command in the UNIX editor is the 'm' command, which moves a lot of lines from one place to another in a file. For example, 5,10m20 picks up lines 5 through 10 and moves them a

#print A convenient abbreviation for the command '1,$p' is simply '%', which just prints the contents of a file. In this directory there is a file named 'tree'. Print the contents with the command ab

#print How does the editor choose a line to print? It always remembers a 'current line', which is the last line of the file originally, but you can choose any line you want. The command 3p prints t

#print There is one last class of substitutions that you should know about: converting one line into two or more by substituting a newline into the middle. Suppose you want to split the line Now

#print Note that there is quite a list of special characters recognized by the editor: . [ * ^ $ & / What do you do when you want to specifically use one of these characters as itself, rather than fo

#print By now you are probably wondering how you get into the editor if someone else doesn't put you there. The main command interpreter (the shell) recognizes ex as the name of the editor. You can