symlink

SYMLINK(2)                 Linux Programmer's Manual                SYMLINK(2)



NAME
       symlink, symlinkat - make a new name for a file

SYNOPSIS
       #include <unistd.h>

       int symlink(const char *target, const char *linkpath);

       #include <fcntl.h>           /* Definition of AT_* constants */
       #include <unistd.h>

       int symlinkat(const char *target, int newdirfd, const char *linkpath);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       symlink():
           _XOPEN_SOURCE >= 500 || _POSIX_C_SOURCE >= 200112L
               || /* Glibc versions <= 2.19: */ _BSD_SOURCE

       symlinkat():
           Since glibc 2.10:
               _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:
               _ATFILE_SOURCE

DESCRIPTION
       symlink() creates a symbolic link named linkpath which contains the
       string target.

       Symbolic links are interpreted at run time as if the contents of the
       link had been substituted into the path being followed to find a file
       or directory.

       Symbolic links may contain ..  path components, which (if used at the
       start of the link) refer to the parent directories of that in which the
       link resides.

       A symbolic link (also known as a soft link) may point to an existing
       file or to a nonexistent one; the latter case is known as a dangling
       link.

       The permissions of a symbolic link are irrelevant; the ownership is
       ignored when following the link, but is checked when removal or
       renaming of the link is requested and the link is in a directory with
       the sticky bit (S_ISVTX) set.

       If linkpath exists, it will not be overwritten.

   symlinkat()
       The symlinkat() system call operates in exactly the same way as
       symlink(), except for the differences described here.

       If the pathname given in linkpath is relative, then it is interpreted
       relative to the directory referred to by the file descriptor newdirfd
       (rather than relative to the current working directory of the calling
       process, as is done by symlink() for a relative pathname).

       If linkpath is relative and newdirfd is the special value AT_FDCWD,
       then linkpath is interpreted relative to the current working directory
       of the calling process (like symlink()).

       If linkpath is absolute, then newdirfd is ignored.

RETURN VALUE
       On success, zero is returned.  On error, -1 is returned, and errno is
       set appropriately.

ERRORS
       EACCES Write access to the directory containing linkpath is denied, or
              one of the directories in the path prefix of linkpath did not
              allow search permission.  (See also path_resolution(7).)

       EDQUOT The user's quota of resources on the filesystem has been
              exhausted.  The resources could be inodes or disk blocks,
              depending on the filesystem implementation.

       EEXIST linkpath already exists.

       EFAULT target or linkpath points outside your accessible address space.

       EIO    An I/O error occurred.

       ELOOP  Too many symbolic links were encountered in resolving linkpath.

       ENAMETOOLONG
              target or linkpath was too long.

       ENOENT A directory component in linkpath does not exist or is a
              dangling symbolic link, or target or linkpath is an empty
              string.

       ENOMEM Insufficient kernel memory was available.

       ENOSPC The device containing the file has no room for the new directory
              entry.

       ENOTDIR
              A component used as a directory in linkpath is not, in fact, a
              directory.

       EPERM  The filesystem containing linkpath does not support the creation
              of symbolic links.

       EROFS  linkpath is on a read-only filesystem.

       The following additional errors can occur for symlinkat():

       EBADF  newdirfd is not a valid file descriptor.

       ENOENT linkpath is a relative pathname and newdirfd refers to a
              directory that has been deleted.

       ENOTDIR
              linkpath is relative and newdirfd is a file descriptor referring
              to a file other than a directory.

VERSIONS
       symlinkat() was added to Linux in kernel 2.6.16; library support was
       added to glibc in version 2.4.

CONFORMING TO
       symlink(): SVr4, 4.3BSD, POSIX.1-2001, POSIX.1-2008.

       symlinkat(): POSIX.1-2008.

NOTES
       No checking of target is done.

       Deleting the name referred to by a symbolic link will actually delete
       the file (unless it also has other hard links).  If this behavior is
       not desired, use link(2).

   Glibc notes
       On older kernels where symlinkat() is unavailable, the glibc wrapper
       function falls back to the use of symlink().  When linkpath is a
       relative pathname, glibc constructs a pathname based on the symbolic
       link in /proc/self/fd that corresponds to the newdirfd argument.

SEE ALSO
       ln(1), namei(1), lchown(2), link(2), lstat(2), open(2), readlink(2),
       rename(2), unlink(2), path_resolution(7), symlink(7)

COLOPHON
       This page is part of release 5.03 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.



Linux                             2017-09-15                        SYMLINK(2)