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       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 relative to directory file descriptor

SYNOPSIS

       #include <unistd.h>

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

       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.

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 fd was not opened with 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.

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2013 Edition, Standard for Information Technology  --  Portable  Operating  System
       Interface  (POSIX),  The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc  and  The  Open  Group.   (This  is
       POSIX.1-2008  with  the  2013  Technical  Corrigendum  1  applied.)  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.unix.org/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 .