cat

The cat command is used for:

Displaying a text file
```
 cat filename
```
If you would like to display all files in the current directory, use the wildcard * like this:
```
 cat *
```
To view all files or:
```
 cat *.txt
```
To view all .txt files only.
Reading a text file

Sometimes a file will be too large to read since it won't fit on screen and will scroll by at high speed. To bypass this, use the cat command with more or less (however, on some shells the more command is not supported).
```
 cat bigfile | more
```
or
```
 cat bigfile | less
```
Creating a new text file

To create a file named "test.txt":
```
 cat > test.txt
```
Then, type the text you want to save into your file and press Ctrl + D when you are finished.
File concatenation (adding files)

To combine to files and create a new file called "newfile.txt":
```
 cat file1.txt file2.txt > newfile.txt
```
Modifying files

To add data to an existing file named "test.txt":
```
 cat >> test.txt
```
Then type your text, and again, press Ctrl + D when finished.