unlink() - Unix, Linux System Call

NAME

unlink - delete a name and possibly the file it refers to

SYNOPSIS

#include <unistd.h> 
int unlink(const char *pathname);

DESCRIPTION

unlink() deletes a name from the filesystem. If that name was the last link to a file and no processes have the file open the file is deleted and the space it was using is made available for reuse.

If the name was the last link to a file but any processes still have the file open the file will remain in existence until the last file descriptor referring to it is closed.

If the name referred to a symbolic link the link is removed. If the name referred to a socket, fifo or device the name for it is removed but processes which have the object open may continue to use it.

RETURN VALUE

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

ERRORS

Tag	Description
EACCES	Write access to the directory containing pathname is not allowed for the process’s effective UID, or one of the directories in pathname did not allow search permission. (See also path_resolution(2).)
EBUSY (not on Linux)	The file pathname cannot be unlinked because it is being used by the system or another process and the implementation considers this an error.
EFAULT	pathname points outside your accessible address space.
EIO	An I/O error occurred.
EISDIR	pathname refers to a directory. (This is the non-POSIX value returned by Linux since 2.1.132.)
ELOOP	Too many symbolic links were encountered in translating pathname.
ENAMETOOLONG	pathname was too long.
ENOENT	A component in pathname does not exist or is a dangling symbolic link, or pathname is empty.
ENOMEM	Insufficient kernel memory was available.
ENOTDIR	A component used as a directory in pathname is not, in fact, a directory.
EPERM	The system does not allow unlinking of directories, or unlinking of directories requires privileges that the current process doesn’t have. (This is the POSIX prescribed error return; as noted above, Linux returns EISDIR for this case.)
EPERM (Linux only)	The filesystem does not allow unlinking of files.
EPERM or EACCES	The directory containing pathname has the sticky bit (S_ISVTX) set and the process’s effective UID is neither the UID of the file to be deleted nor that of the directory containing it, and the process is not privileged (Linux: does not have the CAP_FOWNER capability).
EROFS	pathname refers to a file on a read-only filesystem.

CONFORMING TO

SVr4, 4.3BSD, POSIX.1-2001.

BUGS

Infelicities in the protocol underlying NFS can cause the unexpected disappearance of files which are still being used.