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Please explain GREP

? What the command does, how it could be used
? Important options or switches
? 3 Examples I can use in a UNIX machine

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see the attachment

Finds text within a file.
grep is not only one of the most useful commands, but also, mastery of grep opens the gates to mastery of other tools such as awk , sed and perl .
grep [-b] [-c] [-h] [-i] [-l] [-n] [-s] [-v] [-w] text filenames
-b Precede each line by the block number on which it was found. This can be useful in locating block
-c Print only a count of the lines that contain the pattern.
-h Prevents the name of the file containing the matching line from being appended to that line. Used when searching multiple files.
-i Ignores case.
-l Displays the files that have the text not the text within the file.
-n Precede each line by its line number in the file (first line is 1).
-s Suppress error messages about nonexistent or unreadable files.
-v Specifies you are looking for files that don't contain the text.
-w Search for the expression as a word as if surrounded by < and >.
text The text that you are searching / not searching for. See also below patterns.
filenames the name of the file that you are searching in.
Kinds of Patterns for searching.
. Matches single character.
* Wild character Example C* if found would pull up CC or CAT...
{} Matches any character contained within the bracket.
^ Represents the beginning of the line, so if you did ^T it would search for any sentence starting with a T.
$ Represents the end of the line, so if you did $. then it would pull up any lines that ended with .
Means to take the next ...

Solution Summary

UNIX COMMANDS are assessed. The command which could not be used is determined. Important options or switches are determined.