CodeForWar

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sed and awk

Some use notes on using sed and awk.


What is sed

sed is a stream editor.

   A stream editor is used to perform basic text transformations on an input stream (a file, or input from a pipeline). While in some ways similar to an editor which permits scripted edits (such as ed), sed works by making only one pass over the input(s), and is consequently more efficient. But it is sed's ability to filter text in a pipeline which particularly distinguishes it from other types of editors.





What is awk

awk command searches files for text containing a pattern.

   When a line or text matches, awk performs a specific action on that line/text. The Program statement tells awk what operation to do; Program statement consists of a series of "rules" where each rule specifies one pattern to search for, and one action to perform when a particular pattern is found. A regular expression enclosed in slashes (/) is an awk pattern to match every input record whose text belongs to that set.