Change the current working directory
Int_Type chdir (String_Type dir)
The chdir
function may be used to change the current working
directory to the directory specified by dir
. Upon success it
returns zero. Upon failure it returns -1
and sets
errno
accordingly.
mkdir, stat_file
Change the mode of a file
Int_Type chmod (String_Type file, Int_Type mode)
The chmod
function changes the permissions of the specified
file to those given by mode
. It returns 0
upon
success, or -1
upon failure setting errno
accordingly.
See the system specific documentation for the C library
function chmod
for a discussion of the mode
parameter.
chown, stat_file
Change the owner of a file
Int_Type chown (String_Type file, Int_Type uid, Int_Type gid)
The chown
function is used to change the user-id and group-id of
file
to uid
and gid
, respectively. It returns
0 upon success and -1 upon failure, with errno
set accordingly.
On most systems, only the superuser can change the ownership of a file.
Some systems do not support this function.
chmod, stat_file
Get the current working directory
String_Type getcwd ()
The getcwd
function returns the absolute pathname of the
current working directory. If an error occurs or it cannot
determine the working directory, it returns NULL
and sets
errno
accordingly.
Under Unix, OS/2, and MSDOS, the pathname returned by this function includes the trailing slash character. It may also include the drive specifier for systems where that is meaningful.
mkdir, chdir, errno
Get a list of the files in a directory
String_Type[] listdir (String_Type dir)
The listdir
function returns the directory listing of all the
files in the specified directory dir
as an array of strings.
It does not return the special files ".."
and "."
as
part of the list.
stat_file, stat_is, length
Get information about a symbolic link
Struct_Type lstat_file (String_Type file)
The lstat_file
function behaves identically to stat_file
but if file
is a symbolic link, lstat_file
returns
information about the link itself, and not the file that it
references.
See the documentation for stat_file
for more information.
On systems that do not support symbolic links, there is no
difference between this function and the stat_file
function.
stat_file, readlink
Create a new directory
Int_Type mkdir (String_Type dir [,Int_Type mode])
The mkdir
function creates a directory whose name is specified
by the dir
parameter with permissions given by the optional
mode
parameter. Upon success mkdir
returns 0, or it
returns -1
upon failure setting errno
accordingly. In
particular, if the directory already exists, the function will fail
and set errno to EEXIST
.
define my_mkdir (dir)
{
if (0 == mkdir (dir)) return;
if (errno == EEXIST) return;
throw IOError,
sprintf ("mkdir %s failed: %s", dir, errno_string (errno));
}
The mode
parameter may not be meaningful on all systems. On
systems where it is meaningful, the actual permissions on the newly
created directory are modified by the process's umask.
rmdir, getcwd, chdir, fopen, errno
String_Type readlink (String_Type path)
Get the value of a symbolic link
The readlink
function returns the value of a symbolic link.
Upon failure, NULL
is returned and errno
set accordingly.
Not all systems support this function.
symlink, lstat_file, stat_file, stat_is
Delete a file
Int_Type remove (String_Type file)
The remove
function deletes a file. It returns 0 upon
success, or -1 upon error and sets errno
accordingly.
rename, rmdir
Rename a file
Int_Type rename (String_Type old, String_Type new)
The rename
function renames a file from old
to new
moving it between directories if necessary. This function may fail
if the directories are not on the same file system. It returns
0 upon success, or -1 upon error and sets errno
accordingly.
remove, errno
Remove a directory
Int_Type rmdir (String_Type dir)
The rmdir
function deletes the specified directory. It returns
0 upon success or -1 upon error and sets errno
accordingly.
The directory must be empty before it can be removed.
rename, remove, mkdir
Get information about a file
Struct_Type stat_file (String_Type file)
The stat_file
function returns information about file
through the use of the system stat
call. If the stat call
fails, the function returns NULL
and sets errno accordingly.
If it is successful, it returns a stat structure with the following
integer-value fields:
st_dev
st_ino
st_mode
st_nlink
st_uid
st_gid
st_rdev
st_size
st_atime
st_mtime
st_ctime
See the C library documentation of stat
for a discussion of the
meanings of these fields.
The following example shows how the stat_file
function may be
used to get the size of a file:
define file_size (file)
{
variable st;
st = stat_file(file);
if (st == NULL)
throw IOError, "Unable to stat $file"$;
return st.st_size;
}
lstat_file, stat_is
Parse the st_mode field of a stat structure
Char_Type stat_is (String_Type type, Int_Type st_mode)
The stat_is
function returns a boolean value according to
whether or not the st_mode
parameter is of the specified type.
Specifically, type
must be one of the strings:
"sock" (socket)
"fifo" (fifo)
"blk" (block device)
"chr" (character device)
"reg" (regular file)
"lnk" (link)
"dir" (dir)
It returns a non-zero value if st_mode
corresponds to
type
.
The following example illustrates how to use the stat_is
function to determine whether or not a file is a directory:
define is_directory (file)
{
variable st;
st = stat_file (file);
if (st == NULL) return 0;
return stat_is ("dir", st.st_mode);
}
stat_file, lstat_file
Create a symbolic link
status = symlink (String_Type oldpath, String_Type new_path)
The symlink
function may be used to create a symbolic link
named new_path
for oldpath
. If successful, the function
returns 0, otherwise it returns -1 and sets errno
appropriately.
This function is not supported on all systems and even if supported, not all file systems support the concept of a symbolic link.
readlink