| basename() | Return the base name of a file if the path of the file is provided as a parameter to the basename() function. | 
| chgrp() | Change the user group of the specified file. | 
| chmod() | Change the mode of a specified file to a specific mode given by the user. | 
| chown() | Change the owner of the specified file. | 
| copy() | It is used to make a copy of a specified file. | 
| dirname() | Return the directory name of a given path. | 
| disk_free_space() | Return the amount of free space in a specified directory. | 
| disk_total_space() | Return the total space of a specified directory. | 
| fclose() | Close a file pointed by an open file pointer. | 
| feof() | Test for the end-of-file on a file pointer. | 
| fflush() | Write all the buffered output to an open file. | 
| fgetc() | Return a single character from an open file. | 
| fgets() | Return a line from a file pointer and it stops returning at a specified length. | 
| fgetss() | Return a line from an open file after removing HTML and PHP tags from the respective file. | 
| file_exists() | Check whether a file or directory exists or not. | 
| file_get_contents() | It is used to read a file into a string. | 
| file_put_contents() | It is used to write a string to a file. | 
| fileatime() | Return the last access time of a specified file. | 
| filectime() | Return the last time the specified file was changed. | 
| filemtime() | Return the last time of a specified file when its content was modified. | 
| fileperms() | Return the permissions given to a file or a directory. | 
| filesize() | Return the size of a specified file | 
| filetype() | Return the file type of a specified file or a directory. | 
| SplFileObject flock() | It is used to apply portable lock on the file. | 
| fnmatch() | Match a filename or string against a specified pattern. | 
| fopen() (Function open file or URL) | It is used to open a file or an URL. | 
| fpassthru() | Read data from a current position from a specified file until end of file . | 
| fputcsv() | Format a line as CSV(comma separated values) file and writes it to an open file | 
| fputs() | It is used to write to an open file. | 
| fread() | Reads up to length bytes from the file pointer referenced by file from an open file. | 
| fseek() | It is used to seek in an open file. | 
| fstat() | Return information about an open file. | 
| ftell() | Return the current position in an open file. | 
| ftruncate() | It is used to truncate(shorten) an open file to the specified length. | 
| fwrite() | It is used to write to an open file. | 
| is_dir() | Check whether the specified file is a directory or not. | 
| is_executable() | Check whether the specified file is an executable file or not. | 
| is_file() | Check whether the specified file is a regular file or not. | 
| is_link() | Check whether the specified file is a symbolic link or not. | 
| is_readable() | Check whether the specified file exists and is readable or not. | 
| is_uploaded_file() | Check whether the specified file uploaded via HTTP POST or not. | 
| is_writable() | Check whether the specified file is writable or not. | 
| link() | The link() creates a hard link for a specified target. | 
| lstat() | Return information about a file or a symbolic link. | 
| mkdir() | Creates a new directory with the specified pathname | 
| pathinfo() | Return information about a path using an associative array or a string. | 
| pclose() | The pclose() closes a pipe opened by the popen() function. | 
| popen() | Open a pipe to the program specified by the user using the command parameter. | 
| readfile() | Read a file and write it to the output buffer. | 
| realpath() | Return the canonicalized absolute pathname. | 
| rename() | It is used to rename a file or directory. | 
| rewind() | Set the position of the file pointer to the beginning of the file. | 
| rmdir() | It is used to remove an empty directory. | 
| stat() | It  is used to return information of a file | 
| symlink() | Create a symbolic link for a target that already exists. | 
| tmpfile() | Create a temporary file with a unique name in read-write (w+) mode. | 
| touch() | It is used setting the access and modification time of a specified file. | 
| unlink() | It is used to delete files. It is similar to UNIX unlink() function. |