A complete file specification consists of a file name optionally preceded by a pathname that specifies a directory. The pathname can be in one of two forms:
An absolute pathname, where the directory is specified relative to the root directory. The first character is a slash (/). For example, the following directory and file name refer to the file named testdata in the /usr/users/gdata directory: /usr/users/gdata/testdata
A relative pathname, where the specified directory is relative to the current directory. Relative pathnames do not begin with a slash (/). The following example uses a relative pathname from the current directory /usr/users to refer to the same file testdata in the gdata/ subdirectory: gdata/testdata
Directory names and file names should not contain any operating system wildcard characters (such as *, ?, and the [ ] construct). You can use the tilde (~) character as the first character in a pathname to refer to a top-level directory as in the C shell.
When specifying files, keep in mind that trailing and leading blanks are removed from character expression names, but not from Hollerith (numeric array) names.
File names are case-sensitive and can consist of uppercase and lowercase letters. For example, the following file names represent three different files: