Beginner - Advanced Level Users.
For people who create and modify text files, sed and awk are power tools for editing. Sed, awk and regular expressions allow programmers and system administrators to automate editing tasks that need to be performed on one of more files, to simplify the task of performing the same edits on multiple files, and to write conversion programs.
This book is a companion volume to 'Sed & Awk, 2nd Edition', and 'Unix In A Nutshell'. This small book is a handy reference guide to the information presented in the larger volumes, presenting a concise summary of regular expressions and pattern matching,a and summaries of sed and awk.