NAME

shm_unlink − unlink a shared memory object

SYNOPSIS

int shm_unlink(const char ∗path);

DESCRIPTION

shm_unlink removes the directory entry named by the path name pointed to by path and decrements the link count of the shared memory object referenced by the directory entry.  When all links to a shared memory object have been removed and no process has the object open, the space occupied by the object is freed and the object ceases to exist.  If one or more processes have the shared memory object open when the last link is removed, space occupied by the object is not released until all references to the object have been closed. 

Upon successful completion shm_unlink marks for update the st_ctime and st_mtime fields of the parent directory. Also, if the shared memory object’s link count is not zero, the st_ctime field of the object is marked for update. 

The named shared memory object is unlinked unless one or more of the following are true:

EACCES Search permission is denied for a component of the path prefix. 

EACCES Write permission is denied on the directory containing the link to be removed. 

EACCES The parent directory has the sticky bit set and the shared memory object is not writable by the user; the user does not own the parent directory and the user does not own the shared memory object;

EBUSY The entry to be unlinked is the mount point for a mounted file system. 

EFAULT path points outside the process’s allocated address space. 

EINTR A signal was caught during the shm_unlink system call. 

ELOOP Too many symbolic links were encountered in translating path. 

EMULTIHOP Components of path require hopping to multiple remote machines and the file system does not allow it. 

ENAMETOOLONG The length of the path argument exceeds {PATH_MAX}, or the length of a path component exceeds {NAME_MAX} while _POSIX_NO_TRUNC is in effect. 

ENOENT The named shared memory object does not exist or is a null pathname.  The user is not a super-user. 

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

EPERM The named shared memory object is a directory and the effective user ID of the process is not super-user. 

ETXTBSY The entry to be unlinked is the last link to a pure procedure (shared text) file that is being executed. 

EROFS The directory entry to be unlinked is part of a read-only file system. 

ENOLINK path points to a remote machine and the link to that machine is no longer active. 

SEE ALSO

unlink(2), shm_open(3X). 

DIAGNOSTICS

Upon successful completion, a value of 0 is returned.  Otherwise, a value of −1 is returned and errno is set to indicate the error. 

  —  POSIX 1003.4 Extensions