SunWorld: Hands-off editing with sed, Part 2

“At the simplest level, sed reads in a line of text, applies
the first transformation rule to it, then the second, then the
third, and so on until all transformation rules are used up.
The resulting changed line is then output. Here are some simple
rules to remember when writing sed scripts:”

“1.All editing commands in a script are applied, in order, to
each line of input.
2.Each command is applied to all the lines unless the line address
limits the affected lines.
3.Original files are unchanged. The output result is written to
standard output.”

“The last rule is perhaps the most calming because sed can be
scary to a new user and appears to be an automated, out of control,
seek-and-destroy utility.”

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