Regular Expressions and file formatting
A regular expression is used to [Search/replace/delete] one or more strings by arranging special characters in a column. In short, a regular expression is an expression used for string processing.
Common grep commands for Regular Expressions
Grep: searches for strings in the data and retrieves them in an integer unit.
Grep is a powerful string processing tool with many parameter settings and usage,
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The ^ symbol is different from the inside and outside of the character set ([]). In [], it indicates "reverse selection". In [], it indicates the meaning of locating the beginning of a row.
1. Use brackets [] to search for collection characters
2. start and end of a line ^ $
3. Any character. Repeated characters *
4. Limit the continuous re character range {}
Summary of special characters in Regular Expressions:
Sed Tool
Sed: analyzes standard input data and replaces, adds, deletes, and retrieves data.
File formatting and Processing
Printf: easy-to-use data display tool for formatting and Printing
Awk: An easy-to-use data processing tool
File comparison tools: diff, CMP, patch
PR: file Printing
Important Review