system_link(3f) - [M_system:FILE_SYSTEM] link one file to another
file relative to two directory file descriptors
(LICENSE:PD)
elemental impure integer function link(oldpath,newpath);
character(len=*),intent(in) :: oldpath
character(len=*),intent(in) :: newpath
The link() function shall create a new link (directory entry)
for the existing file, path1.
The path1 argument points to a pathname naming an existing
file. The path2 argument points to a pathname naming the
new directory entry to be created. The link() function shall
atomically create a new link for the existing file and the link
count of the file shall be incremented by one.
If path1 names a directory, link() shall fail unless the process
has appropriate privileges and the implementation supports using
link() on directories.
If path1 names a symbolic link, it is implementation-defined
whether link() follows the symbolic link, or creates a new link
to the symbolic link itself.
Upon successful completion, link() shall mark for update the
last file status change timestamp of the file. Also, the last
data modification and last file status change timestamps of the
directory that contains the new entry shall be marked for update.
If link() fails, no link shall be created and the link count of
the file shall remain unchanged.
The implementation may require that the calling process has
permission to access the existing file.
The linkat() function shall be equivalent to the link() function
except that symbolic links shall be handled as specified by the
value of flag (see below) and except in the case where either path1
or path2 or both are relative paths. In this case a relative path
path1 is interpreted relative to the directory associated with
the file descriptor fd1 instead of the current working directory
and similarly for path2 and the file descriptor fd2. If the
file descriptor was opened without O_SEARCH, the function shall
check whether directory searches are permitted using the current
permissions of the directory underlying the file descriptor. If
the file descriptor was opened with O_SEARCH, the function shall
not perform the check.
Values for flag are constructed by a bitwise-inclusive OR of
flags from the following list, defined in <fcntl.h>:
AT_SYMLINK_FOLLOW
If path1 names a symbolic link, a new link for the target
of the symbolic link is created.
If linkat() is passed the special value AT_FDCWD in the fd1 or
fd2 parameter, the current working directory shall be used for the
respective path argument. If both fd1 and fd2 have value AT_FDCWD,
the behavior shall be identical to a call to link(), except that
symbolic links shall be handled as specified by the value of flag.
Some implementations do allow links between file systems.
If path1 refers to a symbolic link, application developers should
use linkat() with appropriate flags to select whether or not the
symbolic link should be resolved.
If the AT_SYMLINK_FOLLOW flag is clear in the flag argument and
the path1 argument names a symbolic link, a new link is created
for the symbolic link path1 and not its target.
Upon successful completion, these functions shall return
0. Otherwise, these functions shall return -1 and set errno to
indicate the error.
Creating a Link to a File
program demo_system_link
use M_system, only : system_link, system_perror
integer :: ierr
ierr = system_link('myfile1','myfile2')
if(ierr.ne.0)then
call system_perror('*demo_system_link*')
endif
end program demo_system_link
| Type | Intent | Optional | Attributes | Name | ||
|---|---|---|---|---|---|---|
| character(len=*), | intent(in) | :: | oldname | |||
| character(len=*), | intent(in) | :: | newname |
elemental impure function system_link(oldname,newname) result(ierr)
! ident_12="@(#) M_system system_link(3f) call link(3c) to create a file link"
character(len=*),intent(in) :: oldname
character(len=*),intent(in) :: newname
integer :: ierr
integer(kind=c_int) :: c_ierr
character(kind=c_char,len=1),allocatable :: temp1(:)
character(kind=c_char,len=1),allocatable :: temp2(:)
interface
function c_link(c_oldname,c_newname) bind (C,name="link") result (c_ierr)
import c_char,c_int
character(kind=c_char,len=1),intent(in) :: c_oldname(*)
character(kind=c_char,len=1),intent(in) :: c_newname(*)
integer(kind=c_int) :: c_ierr
end function c_link
end interface
temp1 = str2_carr(trim(oldname)) ! kludge for bug in ifort (IFORT) 2021.3.0 20210609
temp2 = str2_carr(trim(newname)) ! kludge for bug in ifort (IFORT) 2021.3.0 20210609
c_ierr=c_link(temp1,temp2)
ierr=c_ierr
end function system_link