PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

NAME

       symlink, symlinkat — make a symbolic link

SYNOPSIS

       #include <unistd.h>

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

       #include <fcntl.h>

       int symlinkat(const char *path1, int fd, const char *path2);

DESCRIPTION

       The  symlink() function shall create a symbolic link called path2 that contains the string
       pointed to by path1 (path2 is the name of the symbolic link created, path1 is  the  string
       contained in the symbolic link).

       The  string  pointed  to  by  path1  shall  be  treated  only as a string and shall not be
       validated as a pathname.

       If the symlink() function fails for any reason other than [EIO], any file named  by  path2
       shall be unaffected.

       If path2 names a symbolic link, symlink() shall fail and set errno to [EEXIST].

       The  symbolic  link's user ID shall be set to the process' effective user ID. The symbolic
       link's group ID shall be set to the group ID of the parent directory or to  the  effective
       group  ID  of  the process. Implementations shall provide a way to initialize the symbolic
       link's group ID to the group ID of the parent directory.  Implementations  may,  but  need
       not,  provide  an implementation-defined way to initialize the symbolic link's group ID to
       the effective group ID of the calling process.

       The values of the file mode bits for  the  created  symbolic  link  are  unspecified.  All
       interfaces specified by POSIX.1‐2008 shall behave as if the contents of symbolic links can
       always be read, except that the value of the file mode bits returned in the st_mode  field
       of the stat structure is unspecified.

       Upon  successful  completion,  symlink()  shall mark for update the last data access, last
       data modification, and last file status change timestamps of the symbolic link. Also,  the
       last  data  modification  and  last  file  status  change timestamps of the directory that
       contains the new entry shall be marked for update.

       The symlinkat() function shall be equivalent to the symlink() function except in the  case
       where  path2 specifies a relative path. In this case the symbolic link is created relative
       to the directory associated with the file descriptor fd instead  of  the  current  working
       directory.  If  the  access  mode  of  the  open file description associated with the file
       descriptor is not O_SEARCH, the  function  shall  check  whether  directory  searches  are
       permitted  using  the current permissions of the directory underlying the file descriptor.
       If the access mode is O_SEARCH, the function shall not perform the check.

       If symlinkat() is passed the special value AT_FDCWD  in  the  fd  parameter,  the  current
       working  directory  shall  be  used  and  the  behavior  shall  be  identical to a call to
       symlink().

RETURN VALUE

       Upon successful completion, these functions shall return 0.   Otherwise,  these  functions
       shall return -1 and set errno to indicate the error.

ERRORS

       These functions shall fail if:

       EACCES Write  permission  is  denied  in  the  directory  where the symbolic link is being
              created, or search permission is denied for a  component  of  the  path  prefix  of
              path2.

       EEXIST The path2 argument names an existing file.

       EIO    An I/O error occurs while reading from or writing to the file system.

       ELOOP  A  loop  exists  in  symbolic  links  encountered  during  resolution  of the path2
              argument.

       ENAMETOOLONG
              The length of a component of the pathname specified by the path2 argument is longer
              than {NAME_MAX} or the length of the path1 argument is longer than {SYMLINK_MAX}.

       ENOENT A  component of the path prefix of path2 does not name an existing file or path2 is
              an empty string.

       ENOENT or ENOTDIR
              The path2 argument contains at least one non-<slash> character and ends with one or
              more  trailing <slash> characters. If path2 without the trailing <slash> characters
              would name an existing file, an [ENOENT] error shall not occur.

       ENOSPC The directory in which the entry for the new symbolic link is being  placed  cannot
              be  extended  because no space is left on the file system containing the directory,
              or the new symbolic link cannot be created because no space is  left  on  the  file
              system  which  shall contain the link, or the file system is out of file-allocation
              resources.

       ENOTDIR
              A component of the path prefix of path2 names an existing file that  is  neither  a
              directory nor a symbolic link to a directory.

       EROFS  The new symbolic link would reside on a read-only file system.

       The symlinkat() function shall fail if:

       EACCES The access mode of the open file description associated with fd is not O_SEARCH and
              the permissions of the directory underlying fd do not permit directory searches.

       EBADF  The path2 argument does not specify an absolute path and the fd argument is neither
              AT_FDCWD nor a valid file descriptor open for reading or searching.

       ENOTDIR
              The  path2  argument is not an absolute path and fd is a file descriptor associated
              with a non-directory file.

       These functions may fail if:

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

       ENAMETOOLONG
              The  length  of  the  path2 argument exceeds {PATH_MAX} or pathname resolution of a
              symbolic link in the path2 argument produced an intermediate result with  a  length
              that exceeds {PATH_MAX}.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       Like  a  hard  link,  a  symbolic  link  allows a file to have multiple logical names. The
       presence of a hard link guarantees the existence of a file, even after the  original  name
       has  been  removed. A symbolic link provides no such assurance; in fact, the file named by
       the path1 argument need not exist when the link is created. A symbolic link can cross file
       system boundaries.

       Normal  permission  checks are made on each component of the symbolic link pathname during
       its resolution.

RATIONALE

       The purpose of the symlinkat() function is to create symbolic links in  directories  other
       than  the  current  working directory without exposure to race conditions. Any part of the
       path of a file could be  changed  in  parallel  to  a  call  to  symlink(),  resulting  in
       unspecified  behavior. By opening a file descriptor for the target directory and using the
       symlinkat() function it can be guaranteed  that  the  created  symbolic  link  is  located
       relative to the desired directory.

FUTURE DIRECTIONS

       None.

SEE ALSO

       fdopendir(), fstatat(), lchown(), link(), open(), readlink(), rename(), unlink()

       The Base Definitions volume of POSIX.1‐2017, <fcntl.h>, <unistd.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1-2017, Standard for Information Technology -- Portable  Operating  System  Interface
       (POSIX),  The  Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by
       the Institute of Electrical and Electronics Engineers, Inc and The  Open  Group.   In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .