The PHP filectime() function returns the last time a file was changed (regular changes or changes to permissions, owner, group or other metadata).

The PHP filegroup() function returns the group ID of a file.

The PHP fileinode() function returns the inode of the specified file.

The PHP filemtime() function returns the last time the file content was modified.

The PHP fileowner() function returns the user ID (owner) of the specified file.

The PHP fileperms() function returns the permissions for a file.

The PHP filesize() function returns the size of a file.

The PHP filetype() function returns the file type of a file.

The PHP flock() function locks or releases a file.

The PHP fnmatch() function checks if a string or filename matches the given shell wildcard pattern.

The PHP fopen() function opens a file or URL.

The PHP fpassthru() function reads from the current position in a file – until EOF, and then writes the result to the output buffer.

The PHP fputcsv() function formats a line as CSV and writes it to an open file.

The PHP fread() reads from an open file and stops at the end of the file or when it reaches the specified length (whichever comes first).

The PHP fscanf() function parses the input from an open file according to the specified format.

The PHP fseek() function seeks in an open file by moving the file pointer from its current position to a new position, forward or backward, in bytes.

The PHP fstat() function returns information about an open file.

The PHP ftell() function returns the current position of the read/write pointer in an open file.

The PHP ftruncate() function truncates an open file to the specified length.

The PHP fwrite() writes to an open file and will stop at the end of the file (EOF) or when it reaches the specified length, whichever comes first.