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symlink(2) System Calls Manual symlink(2)

NAME

symlink, symlinkat - make a new name for a file

LIBRARY

Standard C library (libc, -lc)

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 <= 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 (except when the
    protected_symlinks feature is enabled, as explained in
    proc(5)), 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.


See openat(2) for an explanation of the need for
    symlinkat().








RETURN VALUE


On success, zero is returned. On error, -1 is returned, and
    errno is set to indicate the error.






ERRORS



  

  
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).)

  

  
(symlinkat()) linkpath is relative but newdirfd is
      neither AT_FDCWD nor a valid file descriptor.

  

  
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.

  

  
linkpath already exists.

  

  
target or linkpath points outside your accessible address
      space.

  

  
An I/O error occurred.

  

  
Too many symbolic links were encountered in resolving
    linkpath.

  

  
target or linkpath was too long.

  

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

  

  
(symlinkat()) linkpath is a relative pathname and
      newdirfd refers to a directory that has been deleted.

  

  
Insufficient kernel memory was available.

  

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

  

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

  

  
(symlinkat()) linkpath is relative and newdirfd is a
      file descriptor referring to a file other than a directory.

  

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

  

  
linkpath is on a read-only filesystem.








VERSIONS


symlinkat() was added in Linux 2.6.16; library support was
    added in glibc 2.4.






STANDARDS


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)







  

    2023-02-05
    Linux man-pages 6.03