Grep Command

By Author: Manish
Total Articles: 4
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1. Grep command works by displaying the name of the file that has been found to have a perfect matching line. This can only be seen if one had specified more than one name. The display will show characters that have special meaning in quotation marks whenever they appear within the pattern parameter. It may be important to have the entire pattern in a single quotation mark if the pattern parameter does not come out as a complicated string. Each character has a role to perform according to the collating sequence put on play at that particular time. The work of the collating sequence in most case is to define other similar elements that can be used as character ranges. In case where there are no files highlighted then the Grep command would make up a standard output.
There are various flags that are used and each has its own meaning and function when the Grep command is in use. These flags are usually in the form of alphabetical characters with quotation marks before each of the characters. The –b flag is used to find block numbers in disk according to context although it can not be put into use with other inputs that ...
... are gotten from pipes. With the –c flag one gets to have only counts that have matching lines displayed. It is also possible to find the –F flag. For this it is used to specify NULL strings patterns that match every line and not regular expressions. There are other types of flags and each has its own use and important function to play.
When using the Grep command for the exit status, it provides exit values also in the form of characters with each having a different action to it. When it displays 0 this means that a match was successfully found, but a 1 means that the command was not successful at getting a perfect match.
There are important factors to consider whenever one is running the Grep command. For one this command is never recommended to be run on particular files because it will not produce accurate results. Furthermore, it is crucial to check that the input lines do not at any one point contain NULL characters and they should always end with characters in the newline. As for the newlines they should never be matched against regular expressions if one is to get excellent results.