Deleting Files
==============
You can delete a file with `unlink' or `remove'.
Deletion actually deletes a file name. If this is the file's only
name, then the file is deleted as well. If the file has other
remaining names (Note:Hard Links), it remains accessible under those
names.
- Function: int unlink (const char *FILENAME)
The `unlink' function deletes the file name FILENAME. If this is
a file's sole name, the file itself is also deleted. (Actually,
if any process has the file open when this happens, deletion is
postponed until all processes have closed the file.)
The function `unlink' is declared in the header file `unistd.h'.
This function returns `0' on successful completion, and `-1' on
error. In addition to the usual file name errors (Note:File Name
Errors), the following `errno' error conditions are defined for
this function:
`EACCES'
Write permission is denied for the directory from which the
file is to be removed, or the directory has the sticky bit
set and you do not own the file.
`EBUSY'
This error indicates that the file is being used by the
system in such a way that it can't be unlinked. For example,
you might see this error if the file name specifies the root
directory or a mount point for a file system.
`ENOENT'
The file name to be deleted doesn't exist.
`EPERM'
On some systems `unlink' cannot be used to delete the name of
a directory, or at least can only be used this way by a
privileged user. To avoid such problems, use `rmdir' to
delete directories. (In the GNU system `unlink' can never
delete the name of a directory.)
`EROFS'
The directory containing the file name to be deleted is on a
read-only file system and can't be modified.
- Function: int rmdir (const char *FILENAME)
The `rmdir' function deletes a directory. The directory must be
empty before it can be removed; in other words, it can only contain
entries for `.' and `..'.
In most other respects, `rmdir' behaves like `unlink'. There are
two additional `errno' error conditions defined for `rmdir':
`ENOTEMPTY'
`EEXIST'
The directory to be deleted is not empty.
These two error codes are synonymous; some systems use one, and
some use the other. The GNU system always uses `ENOTEMPTY'.
The prototype for this function is declared in the header file
`unistd.h'.
- Function: int remove (const char *FILENAME)
This is the ISO C function to remove a file. It works like
`unlink' for files and like `rmdir' for directories. `remove' is
declared in `stdio.h'.