On Unix-like systems block devices are also considered to be regular files
by this function.
Parameters:
filename
The name of the file to check for the existence of.
The name does not support wildcard characters.
On Unix-like systems, if the first character is a ~ (tilde)
character optionally followed by a username, it is replaced by the
current or specified user's home directory.
Returns:
0
The file does not exist.
1
The file exists.
Example 8.25. RexxUtil — SysIsFile
ifSysIsFile(InputFile)thensay"File Exists!"elsesay"File does not exist."