access(2) System Calls access(2)NAMEaccess - determine accessibility of a file
SYNOPSIS
#include <unistd.h>
int access(const char *path, int amode);
DESCRIPTION
The access() function checks the file named by the pathname pointed to
by the path argument for accessibility according to the bit pattern
contained in amode, using the real user ID in place of the effective
user ID and the real group ID in place of the effective group ID. This
allows a setuid process to verify that the user running it would have
had permission to access this file.
The value of amode is either the bitwise inclusive OR of the access
permissions to be checked (R_OK, W_OK, X_OK) or the existence test,
F_OK.
These constants are defined in <unistd.h> as follows:
R_OK Test for read permission.
W_OK Test for write permission.
X_OK Test for execute or search permission.
F_OK Check existence of file
See intro(2) for additional information about "File Access Permission".
If any access permissions are to be checked, each will be checked indi‐
vidually, as described in intro(2). If the process has appropriate
privileges, an implementation may indicate success for X_OK even if
none of the execute file permission bits are set.
RETURN VALUES
If the requested access is permitted, access() succeeds and returns 0.
Otherwise, −1 is returned and errno is set to indicate the error.
ERRORS
The access() function will fail if:
EACCES Permission bits of the file mode do not permit
the requested access, or search permission is
denied on a component of the path prefix.
EFAULT path points to an illegal address.
EINTR A signal was caught during the access() func‐
tion.
ELOOP Too many symbolic links were encountered in
resolving path.
ELOOP A loop exists in symbolic links encountered
during resolution of the path argument.
ENAMETOOLONG The length of the path argument exceeds
{PATH_MAX}, or a pathname component is longer
than {NAME_MAX} while _POSIX_NO_TRUNC is in
effect.
ENOENT A component of path does not name an existing
file or path is an empty string.
ENOLINK path points to a remote machine and the link to
that machine is no longer active.
ENOTDIR A component of the path prefix is not a direc‐
tory.
EROFS Write access is requested for a file on a read-
only file system.
The access() function may fail if:
EINVAL The value of the amode argument is invalid.
ENAMETOOLONG Pathname resolution of a symbolic link produced
an intermediate result whose length exceeds
{PATH_MAX}.
ETXTBSY Write access is requested for a pure procedure
(shared text) file that is being executed.
USAGE
Additional values of amode other than the set defined in the descrip‐
tion might be valid, for example, if a system has extended access con‐
trols.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │Async-Signal-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOintro(2), chmod(2), stat(2), attributes(5), standards(5)SunOS 5.10 23 Apr 2002 access(2)
