Cheat Sheet #day51

`cat` Command Cheatsheet

The cat command in Unix/Linux is used to concatenate and display the contents of files. It stands for "concatenate" and is commonly used to read and output file content. Below are the basic and advanced usages of the cat command along with practical examples.

Basic Usage

Display the contents of a file
```
  cat filename
```
Display the contents of multiple files
```
  cat file1 file2
```
Concatenate multiple files and redirect the output to a new file
```
  cat file1 file2 > newfile
```

Common Options

Number all output lines
```
  cat -n filename
```
Show non-printing characters (except for tabs and the end of line)
```
  cat -v filename
```
Display line ends with a $ sign
```
  cat -E filename
```
Display tabs as ^I
```
  cat -T filename
```
Suppress repeated empty output lines
```
  cat -s filename
```

Examples

Display a single file
```
  cat file.txt
```
Display multiple files
```
  cat file1.txt file2.txt
```

Concatenate files and write to a new file

  cat file1.txt file2.txt > newfile.txt

Number all output lines
```
  cat -n file.txt
```
Show non-printing characters
```
  cat -v file.txt
```
Display line ends
```
  cat -E file.txt
```
Display tabs as ^I
```
  cat -T file.txt
```
Suppress repeated empty lines
```
  cat -s file.txt
```

Advanced Usage

Concatenate files and append to an existing file

  cat file1.txt file2.txt >> existingfile.txt

Create a new file with cat (end input with Ctrl+D)

  cat > newfile.txt
  This is the content of the new file.

Combine cat with other commands using pipes
```
  cat file.txt | grep "search_term"
```

Practical Tips

View Large Files: Use cat to quickly view the contents of large files, but consider using less or more for easier navigation.
Combine Files: Use cat to combine multiple files into a single file.
Create Files: Use cat to create and quickly input content into new files.
Use with Caution: Be careful with output redirection (>) to avoid accidentally overwriting important files.

Quick Reference

Display file contents:
```
  cat filename
```
Number all output lines:
```
  cat -n filename
```
Show non-printing characters:
```
  cat -v filename
```
Display line ends:
```
  cat -E filename
```
Display tabs as ^I:
```
  cat -T filename
```
Suppress repeated empty lines:
```
  cat -s filename
```
Concatenate files:
```
  cat file1 file2 > newfile
```
Append to an existing file:
```
  cat file1 file2 >> existingfile
```
Create a new file:
```
  cat > newfile.txt
```

This cheatsheet covers the essential commands and options for using cat effectively, from displaying file contents to concatenating and creating new files. Adjust the commands according to your specific requirements and environment.

Cheat Sheet #day51 - cat

cat Command Cheatsheet