Searching within Text

• grep: Search for a pattern within files.

  • -i: Ignore case.
  • -r or -R: Recursively search in directories.
  • -v: Invert the search (return lines that don't match).

  $ grep "search_term" file.txt
  This line contains the search_term.
  

```bash
$ grep -i "Search_Term" file.txt
This line contains the search_term.
```

Filtering and Transforming Text

• awk: A versatile programming language for working on files.

  $ echo -e "a 1\nb 2\nc 3" | awk '{print $2}'
  1
  2
  3

• sed: Stream editor for filtering and transforming text.

  $ echo "Hello World" | sed 's/World/Universe/'
  Hello Universe

Sorting and Counting

• sort: Sort lines in text files.

  • -r: Reverse the result of comparisons (descending).
  • -n: Compare according to string numerical value.

  $ echo -e "banana\napple\ncherry" | sort
  apple
  banana
  cherry
  

• uniq: Report or omit repeated lines.

  • -c: Prefix lines by the number of occurrences.

  $ echo -e "a\na\nb\nb\nb\nc" | uniq -c
    2 a
    3 b
    1 c
  

wc: Count words, lines, and characters in files.
- -l: Count lines.
- -w: Count words.
- -c: Count bytes.

  ```bash
  $ echo "Hello World" | wc -w
  2
  ```

Text Display

• cat: Concatenate and display the content of files.

  $ cat file.txt
  This is the content of file.txt.

• tac: Display files in reverse.

  $ echo -e "line1\nline2\nline3" | tac
  line3
  line2
  line1

• nl: Number lines of files.

  $ echo -e "line1\nline2\nline3" | nl
  1  line1
  2  line2
  3  line3

• head: Display the beginning of a file.

  • -n: Specify the number of lines to show.

    $ echo -e "line1\nline2\nline3" | head -n 2
    line1
    line2
  

• tail: Display the end of a file.

  • -n: Specify the number of lines to show.
  • -f: Follow the content of a file in real-time.

    $ echo -e "line1\nline2\nline3" | tail -n 2
    line2
    line3