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link(2)

link(2)                          System Calls                          link(2)



NAME
       link, linkat - link to a file

SYNOPSIS
       #include <unistd.h>

       int link(const char *path1, const char *path2);


       int linkat(int fd1, const char *path1, int fd2, const char *path2,
            int flag);

DESCRIPTION
       The link() function creates a new link (directory entry) for the exist‐
       ing file and increments its link  count  by  one.  The  path1  argument
       points  to  a  path  name  naming  an existing file. The path2 argument
       points to a pathname naming the new directory entry to be created.


       To create hard links, both files must be on the same file system.  Both
       the  old and the new link share equal access and rights to the underly‐
       ing object. No process can make a link to a directory,  file  named  by
       path1 must not be a directory.


       Upon  successful completion, link() marks for update the st_ctime field
       of the file. Also, the st_ctime and st_mtime fields  of  the  directory
       that contains the new entry are marked for update.


       If  link()  fails,  no  link  is created and the link count of the file
       remains unchanged.


       The linkat() function is equivalent to link() except in the case  where
       either  path1 or path2 or both are relative paths. In this case a rela‐
       tive 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 checks 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 does 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 is used for the respective
       path argument. If both fd1 and fd2 have value AT_FDCWD, the behavior is
       identical to a call to link().


       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.

RETURN VALUES
       Upon  successful  completion, 0 is returned. Otherwise, −1 is returned,
       no link is created, and errno is set to indicate the error.

ERRORS
       The link() and linkat() functions will fail if:

       EACCES          A component of either path prefix denies search permis‐
                       sion,  or  the  requested  link  requires  writing in a
                       directory with a mode that denies write permission.


       EDQUOT          The directory where the entry for the new link is being
                       placed  cannot  be extended because the user's quota of
                       disk blocks on that file system has been exhausted.


       EEXIST          The link named by path2 exists.


       EFAULT          The path1  or  path2  argument  points  to  an  illegal
                       address.


       EILSEQ          The  path argument includes non-UTF8 characters and the
                       file system accepts only file names where  all  charac‐
                       ters are part of the UTF-8 character codeset.


       EINTR           A  signal was caught during the execution of the link()
                       function.


       ELOOP           Too many symbolic links were encountered in translating
                       path.


       EMLINK          The  maximum  number  of  links  to  a  file  would  be
                       exceeded.


       ENAMETOOLONG    The length of  the  path1  or  path2  argument  exceeds
                       PATH_MAX,  or  the length of a path1 or path2 component
                       exceeds NAME_MAX while _POSIX_NO_TRUNC is in effect.


       ENOENT          The path1 or path2 argument is a null pathname; a  com‐
                       ponent  of  either  path  prefix does not exist; or the
                       file named by path1 does not exist.


       ENOLINK         The path1 or path2 argument points to a remote  machine
                       and the link to that machine is no longer active.


       ENOSPC          The  directory  that  would  contain the link cannot be
                       extended.


       ENOTDIR         A component of either path prefix is not a directory.


       EPERM           The file named by path1 is a directory; this  implemen‐
                       tation prohibits links to directories.

                       The  effective  user ID does not match the owner of the
                       file and  the  {PRIV_FILE_LINK_ANY}  privilege  is  not
                       asserted in the effective set of the calling process.


       EROFS           The requested link requires writing in a directory on a
                       read-only file system.

                       The file named by path1 is  read-only  because  of  the
                       mwac(7) policy.


       EXDEV           The link named by path2 and the file named by path1 are
                       on different logical devices (file systems).



       The linkat() function will fail if:

       EBADF    The path1 or path2 argument does not specify an absolute  path
                and the fd1 or fd2 argument, respectively, is neither AT_FDCWD
                nor a valid file descriptor open for reading.



       The link() and linkat() functions may fail if:

       ELOOP           More than {SYMLOOP_MAX} symbolic links were encountered
                       during resolution of the path1 or path2 argument.


       ENAMETOOLONG    The  length  of a pathname exceeds {PATH_MAX}, or path‐
                       name resolution of a symbolic link produced an interme‐
                       diate result with a length that exceeds {PATH_MAX}.


       EXDEV           The link named by path2 and the file named by path1 are
                       on different logical devices (file systems).



       The linkat() function may fail if:

       EINVAL     The value of the flag argument is not valid.


       ENOTDIR    The path1 or path2 argument is not an absolute path and  fd1
                  or  fd2,  respectively,  is  neither  AT_FDCWD  nor  a  file
                  descriptor associated with a directory.


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) ATTRIBUTE  TYPEAT‐
       TRIBUTE  VALUE  _  Interface StabilityCommitted _ MT-LevelAsync-Signal-
       Safe _ StandardSee standards(7).


SEE ALSO
       symlink(2), unlink(2),  mwac(7),  attributes(7),  privileges(7),  stan‐
       dards(7)



Oracle Solaris 11.4               19 Mar 2014                          link(2)
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