Page 760
getdomainname, setdomainname—Gets/sets domain name
SYNOPSIS
#include <unistd.h> int getdomainname(char *name, size_t len); int setdomainname(const char *name, size_t len);
DESCRIPTION
These functions are used to access or to change the domain name of the current processor.
RETURN VALUE
On success, 0 is returned. On error, _1 is returned and errno is set appropriately.
ERRORS
| EINVAL | For getdomainname, name points to NULL or name is longer than len. |
| EPERM | For setdomainname, the caller was not the superuser. |
| EINVAL | For setdomainname, len was too long. |
CONFORMS TO
POSIX does not specify these calls.
BUGS
getdomainname is not compliant with other implementations because they always return len bytes, even if name is longer. Linux, however, returns EINVAL in this case (as of DLL 4.4.1 libraries).
NOTES
Under Linux, getdomainname is implemented at the library level by calling uname(2).
SEE ALSO
gethostname(2), sethostname(2), uname(2)
Linux 0.99.11, 22 July 1993
getdtablesize—Gets descriptor table size
SYNOPSIS
#include <unistd.h> int getdtablesize(void);
DESCRIPTION
getdtablesize returns the maximum number of files a process can have open.
NOTES
getdtablesize is implemented as a library function in DLL 4.4.1. This function returns OPEN_MAX (set to 256 in Linux 0.99.11) if OPEN_MAX was defined when the library was compiled. Otherwise, _1 is returned and errno is set to ENOSYS.
Page 761
SEE ALSO
close(2), dup(2), open(2)
Linux 0.99.11, 22 July 1993
getgid, getegid—Gets group identity
SYNOPSIS
#include <unistd.h> gid_t getgid(void); gid_t getegid(void);
DESCRIPTION
getgid returns the real group ID of the current process.
getegid returns the effective group ID of the current process.
The real ID corresponds to the ID of the calling process. The effective ID corresponds to the set ID bit on the file being executed.
ERRORS
These functions are always successful.
CONFORMS TO
POSIX, BSD 4.3
SEE ALSO
setregid(2), setgid(2)
Linux 0.99.11, 23 July 1993
getgroups, setgroups—Gets/sets group access list
SYNOPSIS
#include <unistd.h> int getgroups(int size, gid_t list[]); #define_USE_BSD #include <grp.h> int setgroups(size_t size, const gid_t *list);
DESCRIPTION
| getgroups | Up to size supplemental groups are returned in list. If size is 0, list is not modified, but the total number of supplemental groups for the process is returned. |
| setgroups | Sets the supplemental groups for the process. Only the superuser may use this function. |
Page 762
RETURN VALUE
| getgroups | On success, the number of groups stored in list is returned (if size is 0, however, the number of supplemental group IDs associated with the process is returned). On error, _1 is returned and errno is set appropriately. |
| setgroups | On success, 0 is returned. On error, _1 is returned and errno is set appropriately. |
ERRORS
| EFAULT | list has an invalid address. |
| EPERM | For setgroups, the user is not the superuser. |
| EINVAL | For setgroups, gidsetsize is greater than NGROUPS (32 for Linux 0.99.11). |
CONFORMS TO
getgroups conforms to POSIX.1 (and is present in BSD 4.3). Since setgroups requires privilege, it is not covered under POSIX.1.
BUGS
The USE BSD flag probably shouldn't be required for setgroups.
SEE ALSO
initgroups(3)
Linux 0.99.11, 23 July 1993
gethostid, sethostid—Gets/sets the unique identifier of the current host
SYNOPSIS
#include <unistd.h> long int gethostid(void); int sethostid(long int hostid);
DESCRIPTION
Get or set a unique 32-bit identifier for the current machine. The 32-bit identifier is intended to be unique among all UNIX systems in existence. This normally resembles the Internet address for the local machine, as returned by gethostbyname(3), and thus usually never needs to be set.
The sethostid call is restricted to the superuser.
The hostid argument is stored in the file /etc/hostid.
RETURNS VALUES
gethostid returns the 32-bit identifier for the current host as set by sethostid(2).
CONFORMS TO
POSIX.1 does not define these functions, but ISO/IEC 9945-1:1990 mentions them in B.4.4.1.
FILES
/etc/hostid
Page 763
SEE ALSO
hostid(1), gethostbyname(3)
Linux 0.99.13, 29 November 1993
gethostname, sethostname—Gets/sets hostname
SYNOPSIS
#include <unistd.h> int gethostname(char *name, size_t len); int sethostname(const char *name, size_t len);
DESCRIPTION
These functions are used to access or to change the hostname of the current processor.
RETURN VALUE
On success, 0 is returned. On error, _1 is returned and errno is set appropriately.
ERRORS
| EINVAL | len is negative or, for sethostname, larger than the maximum allowed size. For gethostname on Linux/i386, len is smaller than the actual size. |
| EPERM | For sethostname, the caller was not the superuser. |
| EFAULT | name is an invalid address. |
CONFORMS TO
POSIX.1 does not define these functions, but ISO/IEC 9945-1:1990 mentions them in B.4.4.1.
BUGS
Some other implementations of gethostname successfully return len bytes even if name is longer. Linux/Alpha complies with this behavior. Linux/i386, however, returns EINVAL in this case (as of DLL 4.6.27 libraries).
NOTES
Under Linux/Alpha, gethostname is a system call. Under Linux/i386, gethostname is implemented at the library level by calling uname(2).
SEE ALSO
getdomainname(2), setdomainname(2), uname(2)
Linux 1.3.6, 22 July 1995
getitimer, setitimer—Gets/sets value of an interval timer
SYNOPSIS
#include <sys/time.h> int getitimer(int which, struct itimerval *value); int setitimer(int which,conststruct itimer-val *value, struct itimerval *ovalue);