# LaTeX Splitting the Input

A large document requires a lot of input. Rather than putting the whole input in a single large file, it's more efficient to split it into several smaller ones. Regardless of how many separate files you use, there is one that is the root file; it is the one whose name you type when you run LaTeX.

### \include

```  \include{file}
```
The \include command is used in conjunction with the \includeonly command for selective inclusion of files. The file argument is the first name of a file, denoting FILE.TEX. If file is one the file names in the file list of the \includeonly command or if there is no \includeonly command, the \include command is equivalent to

```  \clearpage \input{file} \clearpage
```
except that if the file FILE.TEX does not exist, then a warning message rather than an error is produced. If the file is not in the file list, the \include command is equivalent to \clearpage.

The \include command may not appear in the preamble or in a file read by another \include command.

### \includeonly

``` \includeonly{file_list}
```
The \includeonly command controls which files will be read in by an \include command. It can only appear in the preamble.

### \input

``` \input{file}
```
The \input command causes the indicated file to be read and processed, exactly as if its contents had been inserted in the current file at that point. The file name may be a complete file name with extension or just a first name, in which case the file FILE.TEX is used.

### \endinput

The \endinput command means no more input from the file. All material after \endinput is discarded.