chown(2) System Calls Manual chown(2)
NAME
chown, lchown, fchown - Changes the owner and group IDs of a file
SYNOPSIS
#include <unistd.h>
int chown( const char *path, uid_t owner, gid_t group );
int lchown( const char *path, uid_t owner, gid_t group );
int fchown( int filedes, uid_t owner, gid_t group );
STANDARDS
Interfaces documented on this reference page conform to industry standards as follows:
chown(): POSIX.1, XPG4, XPG4-UNIX
fchown(): POSIX.1, XPG4-UNIX
lchown(): POSIX.1, XPG4-UNIX
Refer to the standards(5) reference page for more information about industry standards and associated tags.
PARAMETERS
Specifies the name of the file whose owner ID, group ID, or both are to be changed. When the path parameter refers to a symbolic link, the
behaviors of the chown() and the lchown() functions differ. The chown() function changes the ownership of the file pointed to by the sym-
bolic link. The lchown() function changes the ownership of the symbolic link file itself. Specifies a valid open file descriptor. Speci-
fies a numeric value representing the owner ID. Specifies a numeric value representing the group ID.
DESCRIPTION
The chown(), lchown() and fchown() functions change the owner and group of a file.
A process can change the value of the owner ID of a file only if the process has superuser privilege. A process can change the value of
the file group ID if the effective user ID of the process matches the owner ID of the file, or if the process has superuser privilege. A
process without superuser privilege can change the group ID of a file only to the value of its effective group ID or to a value in its sup-
plementary group list.
If the value of the owner ID is changed and the process does not have superuser privilege, the set-user ID attribute (the S_ISUID bit) of a
regular file is cleared.
The set-user ID attribute (S_ISUID bit) of a file is cleared upon successful return if: The file is a regular file. The process does not
have superuser privilege.
The set-group ID attribute (S_ISGID bit) of a file is cleared upon successful return if: The file is a regular file. The process does not
have superuser privilege.
If the owner or group parameter is specified as (uid_t)-1 or (gid_t)-1 respectively, the corresponding ID of the file is unchanged.
Upon successful completion, the chown(), lchown(), and fchown() functions mark the st_ctime field of the file for update.
RETURN VALUES
Upon successful completion, the chown(), lchown(), and fchown() functions return a value of 0 (zero). Otherwise, a value of -1 is returned,
the owner and group of the file remain unchanged, and errno is set to indicate the error.
ERRORS
If the chown() and lchown() functions fail, errno may be set to one of the following values: Search permission is denied on a component of
path. The path parameter is an invalid address. The owner or group ID is not a value supported by this implementation. Too many links
were encountered in translating path. The length of the path argument exceeds PATH_MAX or a pathname component is longer than NAME_MAX.
The path parameter does not exist or is an empty string. A component of path is not a directory. The effective user ID does not match the
ID of the owner of the file, and the calling process does not have appropriate privilege and _POSIX_CHOWN_RESTRICTED indicates that such
privilege is required. The named file resides on a read-only file system. The process' root or current directory is located in a virtual
file system that has been unmounted.
If the fchown() function fails, errno may be set to one of the following values: The file descriptor filedes is not valid. The owner or
group ID is not a value supported by this implementation.
RELATED INFORMATION
Functions: chmod(2)
Commands: chown(1)
Standards: standards(5) delim off
chown(2)