Change the current working directory.
Integer_Type chdir (String_Type dir)
The chdir function may be used to changed the current working
directory to the directory specified by dir. Upon sucess it
returns zero; however, upon failure it returns -1 and sets
errno accordingly.
mkdir, stat_file
Change the mode of a file
Integer_Type chmod (String_Type file, Integer_Type mode)
The chmod function changes the permissions of file to those
specified 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
Integer_Type chown (String_Type file, Integer_Type uid, Integer_Type gid)
The chown function is used to change the user-id and group-id of
file to uid and gid, respectively. It returns
zero upon success and -1 upon failure, with errno
set accordingly.
On most systems, only the super user 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. Some versions also include the drive specifier.
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
Integer_Type mkdir (String_Type dir, Integer_Type mode)
The mkdir function creates a directory whose name is specified
by the dir parameter with permissions specified by mode.
Upon success mkdir returns zero, or it returns -1 and
sets 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, 0777)) return;
if (errno == EEXIST) return;
verror ("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 and
returns it as a string. Upon failure, NULL is returned and
errno set accordingly.
Not all systems support this function.
lstat_file, stat_file, stat_is
Delete a file
Integer_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
Integer_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 do not refer to the same file system. It returns
0 upon success, or -1 upon error and sets errno accordingly.
remove, errno
Remove a directory
Integer_Type rmdir (String_Type dir)
The rmdir function deletes a 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 fields:
st_dev
st_ino
st_mode
st_nlink
st_uid
st_gid
st_rdev
st_size
st_atime
st_mtime
st_ctime
stat for a discussion 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) verror ("Unable to stat %s", 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, Integer_Type st_mode)
The stat_is function returns a signed character value about
the type of file specified by st_mode. 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)
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