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access(2) [minix man page]

ACCESS(2)							System Calls Manual							 ACCESS(2)

NAME
access - determine accessibility of file SYNOPSIS
#include <sys/types.h> #include <unistd.h> #define R_OK 4/* test for read permission */ #define W_OK 2/* test for write permission */ #define X_OK 1/* test for execute (search) permission */ #define F_OK 0/* test for presence of file */ int access(const char *path, mode_t mode) DESCRIPTION
Access checks the given file path for accessibility according to mode, which is an inclusive or of the bits R_OK, W_OK and X_OK. Specify- ing mode as F_OK (i.e., 0) tests whether the directories leading to the file can be searched and the file exists. The real user ID and the group access list (including the real group ID) are used in verifying permission, so this call is useful to set- UID programs. Notice that only access bits are checked. A directory may be indicated as writable by access, but an attempt to open it for writing will fail (although files may be created there); a file may look executable, but execve will fail unless it is in proper format. RETURN VALUE
If path cannot be found or if any of the desired access modes would not be granted, then a -1 value is returned; otherwise a 0 value is returned. ERRORS
Access to the file is denied if one or more of the following are true: [ENOTDIR] A component of the path prefix is not a directory. [ENAMETOOLONG] The path name exceeds PATH_MAX characters. [ENOENT] The named file does not exist. [EACCES] Search permission is denied for a component of the path prefix. [ELOOP] Too many symbolic links were encountered in translating the pathname. (Minix-vmd) [EROFS] Write access is requested for a file on a read-only file system. [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. The owner of a file has permission checked with respect to the ``owner'' read, write, and execute mode bits, members of the file's group other than the owner have permission checked with respect to the ``group'' mode bits, and all others have permissions checked with respect to the ``other'' mode bits. [EFAULT] Path points outside the process's allocated address space. [EIO] An I/O error occurred while reading from or writing to the file system. SEE ALSO
chmod(2), stat(2). 4th Berkeley Distribution May 22, 1986 ACCESS(2)

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access(2)							System Calls Manual							 access(2)

NAME
access - Determines the accessibility of a file SYNOPSIS
#include <unistd.h> int access ( const char *path, int access_mode) ; STANDARDS
Interfaces documented on this reference page conform to industry standards as follows: access(): XPG4, XPG4-UNIX Refer to the standards(5) reference page for more information about industry standards and associated tags. PARAMETERS
Points to the file pathname. When the path parameter refers to a symbolic link, the access() function returns information about the file pointed to by the symbolic link. Permission to access all components of the path parameter is determined by using a real user ID instead of an effective user ID, and a group access list (including a real group ID) instead of an effective group ID. Specifies the type of access. The bit pattern contained in the access_mode parameter is constructed by a logical OR of the following values: Checks read permission. Checks write permission. Checks execute (search) permission. Checks to see if the file exists. DESCRIPTION
The access() function checks for accessibility of the file specified by a pathname. Only access bits are checked. A directory may be indicated as writable by access(), but an attempt to open it for writing will fail (although files may be created there); a file's access bits may indicate that it is executable, but the execve() function can fail if the file does not contain the proper format. RETURN VALUES
Upon successful completion, the access() function returns value of 0 (zero). Otherwise, a value of -1 is returned and errno is set to indicate the error. ERRORS
If the access() function fails, access to the file specified by the path parameter is denied and errno may be set to one of the following values: Permission bits of the file mode do not permit the requested access, or search permission is denied on a component of the path pre- fix. The owner of a file has permission checked with respect to the ``owner'' read, write, and execute mode bits, members of the file's group other than the owner have permission checked with respect to the ``group'' mode bits, and all others have permissions checked with respect to the ``other'' mode bits. The path parameter points outside the process' allocated address space. The pathname contains a char- acter with the high-order bit set. An I/O error occurred while reading from or writing to the file system. Too many symbolic links were encountered in translating the pathname. A component of a pathname exceeded PATH_MAX characters, or an entire pathname exceeded NAME_MAX characters. The named file does not exist or is an empty string. A component of the path prefix is not a directory. Write access is requested for a file on a read-only file system. RELATED INFORMATION
Functions: chmod(2), stat(2) Standards: standards(5) delim off access(2)
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