# Cheatsheet & Examples: cat

cat command is used to read, concatenate, and display the content of files in the terminal. It can also be used to create, view, or merge files.

## Display file contents

Example Usage:
`cat filename`

What it does:
Prints the content of the specified file to the terminal.

Command-line Arguments Explained:
- filename: The path to the file being read and displayed.

## Concatenate multiple files

Example Usage:
`cat file1 file2 > combined`

What it does:
Combines the contents of `file1` and `file2` into a new file called `combined`.

Command-line Arguments Explained:
- file1, file2: The files to be concatenated.
- `>`: Shell redirection operator, not a `cat` argument, used to direct output to a file.

## Create or overwrite a file

Example Usage:
`cat > newfile`

What it does:
Creates a new file named `newfile` or overwrites an existing one, allowing input to be entered and saved.

Command-line Arguments Explained:
- `>`: Shell redirection operator, not a `cat` argument, used to redirect input to a file.

## Display file with line numbers

Example Usage:
`cat -n filename`

What it does:
Displays the content of `filename` with line numbers added to each line.

Command-line Arguments Explained:
- `-n`: Enables line numbering for the output.

## Append to a file

Example Usage:
`cat >> existingfile`

What it does:
Adds input from standard input to the end of `existingfile` without overwriting it.

Command-line Arguments Explained:
- `>>`: Shell redirection operator, not a `cat` argument, used to append output to a file.

## Display non-printing characters

Example Usage:
`cat -v filename`

What it does:
Displays non-printing characters in `filename` as visible symbols (e.g., tabs as `^I`, newlines as `$.`).

Command-line Arguments Explained:
- `-v`: Enables visualization of non-printing characters.

## Show help information

Example Usage:
`cat --help`

What it does:
Displays a summary of `cat` command options and usage.

Command-line Arguments Explained:
- `--help`: Shows the help message for the `cat` command.

## Pipe file content to another command

Example Usage:
`cat file | grep "pattern"`

What it does:
Passes the content of `file` to the `grep` command for filtering.

Command-line Arguments Explained:
- `|`: Shell pipe operator, not a `cat` argument, used to connect commands.

## Squeeze multiple blank lines

Example Usage:
`cat -s file1 file2`

What it does:
Removes extra blank lines between files when outputting their content.

Command-line Arguments Explained:
- `-s`: Squeezes multiple consecutive blank lines into one.

## Number non-empty lines

Example Usage:
`cat -b filename`

What it does:
Displays the content of `filename` with line numbers, excluding blank lines.

Command-line Arguments Explained:
- `-b`: Enables line numbering, skipping blank lines.