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ULTRIX

POSIX Conformance Document

Order Number: AA-LY25C-TE
June 1990

Product Version:

ULTRIX Version 4.0 or higher

This document is the ULTRIX Operating System, Version 4.0, POSIX Conformance
Document as specified by IEEE Std 1003.1-1988, IEEE Standard Portable Operating System
for Computer Environments and ISO DIS 9945-1 (1989) (POSIX.1).
The ULTRIX Operating System also meets the requirements of the Federal Information
Processing Standard (FIPS 151-1).

digital equipment corporation
maynard, massachusetts

Restricted Rights: Use, duplication, or disclosure by the U.S. Government is subject to restrictions as set forth in
subparagraph (c) (1) (ii) of the Rights in Technical Data and Computer Software clause of DFARS 252.227-7013.
© Digital Equipment Corporation 1988, 1989, 1990

The information in this document is subject to change without notice and should not be construed as a commitment
by Digital Equipment Corporation. Digital Equipment Corporation assumes no responsibility for any errors that may
appear in this document.
The software described in this document is furnished under a license and may be used or copied only in accordance
with the terms of such license.
No responsibility is assumed for the use or reliability of software on equipment that is not supplied by Digital or its
affiliated companies.

The following are trademarks of Digital Equipment Corporation:

Illmalla
CDA
DDIF
DDIS
DEC
DECnet
DECstation

DECUS
DECwindows
DTIF
MASSBUS
MicroVAX
Q-bus
ULTRIX
ULTRIX Mail Connection

ULTRIX Worksystem Software
UNIBUS
VAX
VAXstation
VMS
VMS/ULTRIX Connection
VT

XVI

UNIX is a registered trademark of AT&T in the USA and other countries.

Contents

About This Manual
xi

Audience
Organization

....................................... .. ......... .................... ............. .. ... . ......... .. .

Related Documents

...........................................................................................

xii
xii

Conventions

Scope

Definitions and General Requirements

2.2

Conformance

2.2.3

...........................................................................................

Language-Dependent Services for the C Programming Language

2.2.3.3

Common Usage C Language-Dependent System Support

2-1
2-1
2-1

2.3

General Terms

2-1

2.4

General Concepts

2-3

2.5
2.6
2.7

Error Numbers

Environment Description

.......................................................................... .

2.8

C Language Definitions

............................................................................ .

2.8.2

........................................................................... .

........................................................................................ .

Primitive System Data Types

POSIX Symbols

.................................................................... .

2-3

2-4
2-5
2-5
2-5
2-5
2-6

2.9 Numerical Limits
2.10 Symbolic Constants
3

Process Primitives

3.1

Process Creation and Execution

3-1

3.1.1

........................................................................... .

3-1

....................................................... ..................

3-1

Process Creation

3.1.1.2

Description

Errors

3-1

Execute a File

3-1

3.1.1.4
3.1.2

3.1.2.2
3.1.2.4
3.2

3-2

3.2.1

Wait for Process Tennination

3-2

Description

3-2

Tenninate a Process

3-2

3.2.2

3.2.2.2
Signals
3.3.1

3.3.2

Signal Concepts

3.3.5

Signal Names ................................................................... ..
Signal Generation and Delivery ........................................... ..
Signal Actions ................................................................... .

3-2
3-3
3-3

Description

............................................................ ..

3-3

........................................................................ .

3-3

Errors

.................................................................. .

3-4

............................................................................... .

3-4

Examine and Change Blocked Signals
3.3.5.2

3.3.6

3-2

Manipulate Signal Sets
3.3.3.4

Description

........................................................................ .

Examine Pending Signals
3.3.6.4

............................................................... .

Process Environment

4.2

User Identification

ivContents

3-4

4-1
.........................................................

4-1

.........................................................................

4-1

.................................................... ..........................

4-1

Returns ..............................................................................
Errors ................................................................................

4-1
4-1

Description

Get User Name
4.2.4.3
4.2.4.4

3-4

Get Supplementary Group IDs
4.2.3.2

4.2.4

............................................................... ..

Description

4.2.3

3-4

Delay Process Execution
3.4.3.2

3-4

Errors

Timer Operations
3.4.3

3-2

.............................................................................

Send a Signal to a Process
3.3.2.2

3.3.3

3-2

Description

....................................................................................................

3.3.1.1
3.3.1.2
3.3.1.3

3.4

3-1
3-1

Process Tennination
3.2.1.2

3.3

Description ........................................................................ .
Errors ............................................................................... .

4.4

System Identification

4-1

4.4.1

4-1

System Name
4.4.1.2
4.4.1.4

4.5

Get System Time

...........................................................................

4-2

Errors

................................................................................

4-2

Process Times

...............................................................................

4-2

4.5.1.4
4.5.2

4.5.2.3
4.5.2.4

4.8

Returns ..............................................................................
Errors ................................................................................

4-3
4-3

...................................................

4-3

Description ........................................................................ .
Errors ............................................................................... .

4-3
4-3

..................................................................

4-3

..................................................

4-3

.........................................................................

4-3

...............................................................................................

5-1

Format of Directory Entries .............................................................
Directory Operations ......................................................................

5-1
5-1

Description ........................................................................ .
Errors .............................................................................. ..

5-1
5-1

Description

Files and Directories

5.1

Directories

5.1.2.2
5.1.2.4

Working Directory
5.2.2

4-3
4-3

Get Configurable System Variables
4.8.1.2

5.1.1
5.1.2

4-2

...........................................................

Configurable System Variables
4.8.1

5.2

..............................................................................

Determine Terminal Device Name
4.7.2.2
4.7.2.3

4-2
4-2
4-3

Generate Terminal Pathname
4.7.1.3
4.7.1.4

4.7.2

.......................................................................

Returns
Errors

Terminal Identification
4.7.1

..............................................................................

Environment Access
4.6.1.3
4.6.1.4

4.7

4-2
4-2

Returns
Errors

Environment Variables
4.6.1

4-1
4-2
4-2

Time
4.5.1

4.6

Description ........ ... .. ... ...... . ..... . . ..... ... ............... .. .............. ....
Errors ................................................................................

............................................................... ....................

Working Directory Pathname
5.2.2.2

Description

5-2

..........................................................

5-2

.........................................................................

5-2

Contents v

Returns
Errors

5-2
5-2

General File Creation

5-2

5.2.2.3
5.2.2.4
5.3

5.3.1

Open a File
5.3.1.2

5.3.3

...................................................................................

Description

..........................................................................

5-2
5-2

Set File Creation Mask
5-2
5.3.3.2

5.3.4

Link to a File
5.3.4.2

5.4

5-2

........................................... .....................................

5-3

Description

.........................................................................

5.4.2

Description

...........................................................................

5-3

...... ...................................................................

5-3

Make a FIFO Special File
5.4.2.2

5-3
5-3

Make a Directory
5.4.1.2

Description

...............................................................

5-3

.........................................................................

5-3

File Removal

5-3

5.5.2

5-3

Remove a Directory
5.5.2.2

5.5.3

Description

Rename a File
5.5.3.2

5.6

...................................... ...................................

Special File Creation
5.4.1

5.5

Description

......................................................

-'0 . . . . . . . . . . . . . . . . .

.............................................................................. .

Description

.........................................................................

File Characteristics: Header and Data Structure
5.6.1.2
5.6.1.3

5.6.2
5.6.3

5-4
5-4

............................................................................. .

5-4
5-4

File Accessibility

...........................................................................

5-4

Description .........................................................................
Errors ................................................................................

5-4
5-4

Change File Modes
Description

........................................................................

5-4

.........................................................................

5-4

Change Owner and Group of a File
5.6.5.2
5.6.5.4

vi Contents

The <sys/ stat. h> File Modes ........................................ .
The <sys/ stat. h> Time Entries ...................................... .
.........................................................................

5.6.4.2
5.6.5

5-4

Description

5.6.3.2
5.6.3.4
5.6.4

5-3

................................. .

Get File Status
5.6.2.2

5-3

5-4

File Characteristics
5.6.1

5-3

..................................................

5-4

Description .........................................................................
Errors ........................... ............................ .........................

5-4
5-4

5.7

Configurable Pathname Variables

5.7.1

5-5

Description .........................................................................
Errors ................................................................................

5-5
5-5

Input and Output Primitives

6.4

Input and Output

6.4.2

6-1

Description .............. ...........................................................
Errors ........ ........................................................................

6-1
6-1

....... . ..... .. ..... .... .... ...... ....... ... ...................................

6-1

Description .........................................................................
Errors ................................................................................

6-1
6-1

.......................................................................

6-2

File Control..................................................................................

6-2

Control Operations on Files

6.5.2

6.5.2.2
6.5.2.4
6.5.3

Description .........................................................................
Errors ................................................................................
Description

6-2

.........................................................................

6-2

Device- and Class-Specific Functions

7.1

General Terminal Interface

7.1.2

7-1
..................................................................

7-1

The Controlling Terminal ..................................................... .
Input Processing and Reading Data ....................................... .
Canonical Mode Input Processing ......................................... .
Non-Canonical Mode Input Processing .................................. .
Writing Data and Output Processing ..................................... .
Special Characters .............................................................. .

7-1
7-1
7-1
7-1
7-1
7-2

Interface Characteristics

7.1.1.3
7.1.1.5
7.1.1.6
7.1.1.7
7.1.1.8
7.1.1.9

7-2

Settable Parameters

7.1.2.1
7.1.2.2
7.1.2.3
7.1.2.4
7.1.2.5
7.1.2.6
7.1.2.7

6-2
6-2

....................................................

Reposition ReadIWrite File Offset

6.5.3.2

7.1.1

6-1

............................................................................

Write to a File

6.4.2.2
6.4.2.4
6.5

......................................................................................

Read from a File

6.4.1.2
6.4.1.4

5-5

...............................................

Get Configurable Pathname Variables

5.7.1.2
5.7.1.4

6.4.1

...............................................................

The termios Structure .......................................................... .
Input Modes ...................................................................... .
Output Modes .................................................................... .
Control Modes ................................................................... .
Local Modes ...................................................................... .
Special Control Characters .................................................. .
Baud Rate Functions ........................................................... .

7.1.2.7.2

Description

7-2
7-2
7-2
7-3
7-3
7-3

7-4
7-4

Contents vii

7.1.2.7.4
7.2

7-4
7-4

7.2.2

...................................................................

7-4

.........................................................................

7-4

Line Control Functions

7.2.3

Description

...................................................

7-5

................................................ .........................

7-5

Get Foreground Process Group ID

7.2.3.2
7.2.4

Description

....................................................

7-5

.........................................................................

7-5

Set Foreground Process Group ID

7.2.4.2

Description

Language-Specific Services for the C Programming Language

Conformance

8.1

......................................................................

General Terminal Interface Control Functions

7.2.2.2

Errors

....................................................................................................

8-1

Implementation Conformance

8-1

Referenced C Language Routines

8-1

8.1.1
8.1.2

8-1

Extensions to Time Functions ..........................................................
Extensions to the setlocale Function

8-1
8.1.2.2
8.2

........................................................................ .

Map a Stream Pointer to a File Descriptor

8.2.1.4
8.2.2

....................................... ..

..................................................

8-2

Description .........................................................................
Errors ................................................................................

8-2
8-2
8-2

Other C Language Functions

8.3.2

8-2
8-2

Errors

Open a Stream on a File Descriptor

8.2.2.2
8.2.2.4

8-1
8-2

FILE-Type C Language Functions

8.2.1

8.3

Description

Set Time Zone

8-3
8.3.2.2

8-3

Description

System Databases

9.1

System Databases

.....................................................................................

9-1

9.2

Database Access

.......................................................................................

9-1

9.2.1

Group Database Access

9.2.1.2

viii Contents

Description

................................... ..... .................... ..... ..... ...

9-1
9-1

9.2.1.3
9.2.1.4
9.2.2

Returns
Errors

User Database Access
9.2.2.2
9.2.2.3
9.2.2.4

9-1
9-2
.....................................................................

9-2

Description .........................................................................
Returns ..............................................................................
Errors ................................................................................

9-2
9-2
9-2

Data Interchange Format

10.1

Archive/lnterchange File Format

10-1

10.1.1
10.1.2

10-1
10-1

Extended tar Format
Extended cpio Format

10.1.2.1
10.1.2.2
10.1.2.4
10.1.2.5
10.1.3

Header .............................................................................
File Name ........................................................................
Special Entries ..................................................................
The cpio Values ..............................................................

Multiple Volumes

........................................................................

10-1
10-2
10-2
10-2
10-2

POSIX FIPS Additional Requirements

Contents ix

About This Manual

This document is the ULTRIX Operating System, Version 4.0, POSIX Conformance
Document as specified by IEEE Std 1003.1-1988, IEEE Standard Portable Operating
System/or Computer Environments and ISO DIS 9945-1 (1989) (POSIX.l).
The ULTRIX Operating System also meets the requirements of the Federal
Information Processing Standard (PIPS 151-1).

Audience
The POSIX Conformance Document is written for people who are evaluating
operating systems for POSIX confonnance and those who want to learn how
ULTRIX Version 4.0 implements various POSIX features. The reader should be
familiar with IEEE Std 1003.1-1988 or ISO DIS 9945-1 (1989).

Organization
This document consists of chapters whose sections briefly explain how ULTRIX
Version 4.0 conforms to the implementation-defined features described in POSIX.1.

Related Documents
This manual should be used in conjunction with the ULTRIX Reference
Pages Sections 1-8.
For more detailed information on POSIX.l, refer to IEEE Std 1003.1-1988, IEEE
Standard Portable Operating Systems Interface for Computer Environments or ISO
DIS 9945-1 (1989).
The IEEE Std 1003.1-1988 can be obtained from the following address:
Publication Sales
IEEE Service Center
P.O. Box 1331
445 Hoes Lane
Piscataway, NJ 08855-1331
(201) 981-0060
The ISO document can be obtained from the following address:
ISO Central Secretariat,
1 rue de Varembi,
CH-1211 Geneve 20,
Switzerland
+41 22 7341240
Relevant information is also contained in the PO SIX-related Federal Information
Processing Standards (PIPS) documentation. The PIPS documentation can be
obtained from the following address:
National Technical Information Service
US Department of Commerce
5285 Port Royal Road
Springfield, VA 22161
(703) 487-4650

Conventions
system output This typeface is used in interactive examples to indicate system
output and also in code examples and other screen displays. In
text, this typeface is used to indicate the exact name of a
command, option, partition, pathname, directory, or file.

UPPERCASE
lowercase

The ULTRIX system differentiates between lowercase and
uppercase characters. Literal strings that appear in text,
examples, syntax descriptions, and function definitions must be
typed exactly as shown.

filename

In examples, syntax descriptions, and function definitions, italics
are used to indicate variable values; and in text, to give references
to other documents.

xii About This Manual

Scope

The ULTRIX Operating System, Version 4.0, meets the "conforming
implementation" requirements for an operating system as defined in IEEE Std
1003.1-1988 IEEE Standard Portable Operating System Interfacefor Computer
Environments and ISO DIS 9945-1 (1989) (POSIX.1).
This POSIX Conformance Document has the same structure as POSIX.1 and is
intended to be used in conjunction with that standard.
Sections appearing in this document provide implementation-specific characteristics
of the ULTRIX Operating System.
There are two implementations of the ULTRIX Operating System, Version 4.0, one
for RISe processors and one for VAX processors. The behavior on both processors
is identical with regard to POSIX conformance issues, except where explicitly noted.

Definitions and General Requirements

This chapter provides tenninology, concepts, definitions, and general requirements
used in this document. For additional infonnation on achieving a POSIX.l
conformant environment, see Chapter 8 of this document.

2.2 Conformance
The ULTRIX Operating System, Version 4.0, confonns to ffiEE Std 1003.1-1988,
IEEE Standard Portable Operating System Interface for Computer Environments and
ISO DIS 9945-1 with common usage C language-dependent system support.
The ULTRIX POSIX environment supports the functional behavior described in
POSIX.1. For infonnation on programming in a POSIX environment, refer to the
Guide to Languages and Programming.
The ULTRIX Operating System also meets the requirements of the Federal
Infonnation Processing Standard (FIPS lSI-I).

2.2.3

Language-Dependent Services for the C Programming Language

2.2.3.3

Common Usage C Language-Dependent System Support - The library
functions present in ULTRIX confonn to the ANSI C Standard (X3.159-1989). For
details, see Chapter 8 of this document.

2.3 General Terms
The following paragraphs provide brief descriptions of the implementation-defined
features for ULTRIX systems.

appropriate privileges
On ULTRIX systems, all appropriate privileges are associated with the superuser.

character special file
On ULTRIX systems, types of character special files include terminal device files,
raw storage devices (for example, tapes or disks), and pseudodevices (for example,
/ dev / kmem ).

file
In addition to the file types defined in POSIX.l, ULTRIX systems also have
symbolic links and sockets.

file group class
There are no other members of the file group class beyond those defined in POSIX.l.

parent process ID
A new process is created by a currently active process. The parent process ID of a
process is the process ID of its creator for the lifetime of the creator. After the
creator's lifetime has ended, the parent process ID is the process ID of the
initialization process (process ID = 1).

pathname
On ULTRIX systems, multiple successive slashes (/), including two or more leading
slashes, are interpreted as a single slash.

read-only file system
On ULTRIX systems, a read-only file system is a file system that has been mounted
in one of the following ways:
•

Using the mount system call with the rwflag argument set to 1

•

Using the mount utility with the -r option set

•

U sing the option string r 0 from the / etc / f stab file

Mounting a read-only file system disables writing to the device in which the file
system resides. Operations that require creating, writing, or updating are not
permitted and result in ULTRIX systems issuing the error [EROFS]. ULTRIX
systems do not update the file access time on read requests for files on a read-only
file system. Files and directories that reside on a read-only file system can only be
read.

supplementary group ID
On ULTRIX systems, the effective group ID of a process is included in its list of
supplementary group IDs.

2-2 Definitions and General Requirements

2.4 General Concepts
The following paragraphs provide brief descriptions of the implementation-defined
concepts for ULTRIX systems.

extended security controls
ULTRIX systems do not provide different access control or privilege mechanisms
beyond those described in POSIX.l. Additional security controls provided by
ULTRIX systems do not alter or override the defined semantics of any of the
functions in POSIX.l. For further information, refer to the Security Guide for
Administrators.

file access permissions
ULTRIX systems do not provide additional or alternate file access control
mechanisms.

file times update
Fields marked for update are updated periodically.

2.5 Error Numbers
The error condition [EFAULT] denotes an invalid address in the argument of a call,
as detected by the applicable hardware. When this error is encountered on an
ULTRIX system, the error number (errno) for [EFAULT] is returned. The system
reliably detects [EFAULT], but it is only detected for system calls. Library routines
might get either the signal SIGSEGV or SIGBUS. See the ULTRIX Reference Pages
to determine which routines are considered library routines.
In addition to those errors specified in POSIX.l, the following errors are defined in
<errno. h>. For a more complete description of these errors, see errno(2) in the
ULTRIX Reference Pages.

Error

Description

EADDRINUSE
EADDRNOTAVAIL
EAFNOSUPPORT
EALIGN
EALREADY
ECONNABORTED
ECONNREFUSED
ECONNRESET
EDESTADDRREQ
EDQUOT
EFBIG
EHOSTDOWN
EHOSTUNREACH

Address already in use
Can't assign requested address
Address family not supported by protocol family
Alignment error
Operation already in progress
Software caused connection abort
Connection refused
Connection reset by peer
Destination address required
Disc quota exceeded
Maximum file size is 264_1
Host is down
No route to host

Definitions and General Requirements 2-3

Error

Description

EIDRM
EINPROGRESS
EISCONN
ELOOP
EMSGSIZE
ENETDOWN
ENETRESET
ENETUNREACH
ENOBUFS
ENOMSG
ENOPROTOOPT
ENOTBLK
ENOTCONN
ENOTSOCK
EOPNOTSUPP
EPFNOSUPPORT
EPROCLIM
EPROTONOSUPPORT
EPROTOTYPE
EREMOTE
ESHUTDOWN
ESOCKTNOSUPPORT
ESTALE
ETIMEDOUT
ETOOMANYREFS
ETXTBSY
EUSERS
EWOULDBLOCK

Identifier removed
Operation now in progress
Socket is already connected
Too many levels of symbolic links
Message too long
Network is down
Network dropped connection on reset
Network is unreachable
No buffer space available
No message of desired type
Protocol not available
Block device required
Socket is not connected
Socket operation on non-socket
Operation not supported on socket
Protocol family not supported
Too many processes
Protocol not supported
Protocol wrong type for socket
Too many levels of remote in path
Can't send after socket shutdown
Socket type not supported
Stale NFS file handle
Connection timed out
Too many references: can't splice
Text file busy
Too many users
Resource deadlock would occur

2.6 Primitive System Data Types
In addition to the data types listed in Table 2-1 of POSIX.1, ULTRIX systems define
the following system data type in <sys/types. h>:

Type

Description

time_t

As defined in ANSI C

For additional information, refer to types(5) in the ULTRIX Reference Pages.

2-4 Definitions and General Requirements

2.7 Environment Description
Environment variable names can contain any 8-bit character except an equal sign (=)
or a NUL ('\0'). However, built-in shell commands can only operate on environment
variable names that contain only underscores, digits, and letters (A-Z and a-z) and
that do not begin with a digit.

2.8 C Language Definitions
2.8.2

POSIX Symbols
In addition to the _PO SIX_SOURCE feature test macro, the _XOPEN_SOURCE
macro is also available on ULTRIX systems. This macro enables those features
specified by the X/Open Portability Guide, Issue 3.

2.9 Numerical Limits
The <1 imi t s . h> header contains the following POSIX-related definitions. Note
that these values cannot be changed at runtime.
NGROUPS_MAX
NAME_MAX
MAX_INPUT
MAX CANON
OPEN MAX
PATH_MAX
LINK_MAX
PIPE_BUF

32
255
256
256
64
1024
32766
4096

/*
/*
/*
/*
/*
/*
/*
/*

max
max
max
max
max
max
max
max

*/
# of groups
*/
# of characters in a file name
# of bytes in terminal input queue */
# of bytes in term canon input line */
# of files a process can have open */
*/
# of characters in a pathname
*/
# of links to a single file
*/
# bytes atomic in write to pipe

On the VAX architecture, <1 imi t s . h> also contains the following definition:
ARG MAX

10240

/* max length of arguments to exec */

On the RISC architecture, <1 imi t s . h> also contains the following definition:
ARG MAX

20480

/* max length of arguments to exec */

The symbol CHILD_MAX is not defined in <limits. h>; its value is set at
system configuration time and can be retrieved by the sysconf function.

Definitions and General Requirements 2-5

2.10 Symbolic Constants
The <unistd. h> header contains the following POSIX-related definitions. These
do not vary.
R_OK
4
W OK
2
X OK
1
F_OK
0
SEEK_SET 0
SEEK_CUR 1
SEEK END 2

/*
/*
/*
/*
/*
/*
/*

Test for
Test for
Test for
Test for
Set file
Set file
Set file

"Read" Permission
"Write" Permission
"Execute" (Search) Permission
existence of file
offset to offset
offset to current plus offset
offset to EOF plus offset

*/
*/
*/
*/
*/
*/
*/

/* POSIX options */
_POSIX_JOB_CONTROL
1
/*Job Control Present
*/
_POSIX_SAVED_IDS
1
/*Support saved-set-ids feature
*/
_POS IX_VERS ION
198808L /*POSIX version
*/
_POSIX_CHOWN_RESTRICTED 1
/*chown() restricted to superuser
*/
_POSIX_NO_TRUNC
1
/*Pathname longer than NAME MAX err */
_POS IX_VD ISABLE
0
/*termio(s) special character disable*/

2-6 Definitions and General Requirements

Process Primitives

This chapter describes the system services provided by ULTRIX systems. These
system services deal with processes, interprocess signals, and timers.

3.1

Process Creation and Execution

3.1.1

Process Creation

3.1.1.2

Description - On ULTRIX systems, after a for k () call, a new process (child
process) inherits process characteristics from the process that created it, including
shared memory allocation. Each open directory stream in the child process shares the
directory stream positioning with the corresponding directory stream of the parent.

3.1.1.4

Errors - For the for k () function, ULTRIX systems detect the conditions and
return the corresponding errno value for [ENOMEM].

3.1.2

Execute a File

3.1.2.2

Description - On ULTRIX systems, NULL terminators are included in the
argument byte count. If the argument file does not contain a slash (I) character and
the environment variable PATH is not set, the system searches the current directory
for the file.
In addition to the attributes inherited by a new image as listed in POSIX.l, on
ULTRIX systems, a new process image inherits the following attributes from the
calling process image:

•

Resource usages (see getrusage(2))

•

Interval timers (see getitimer(2))

•

Resource limits (see getrlimit(2))

ARG_MAX is the maximum allowed length of the argument list, including NULL
terminators and environment data.
On ULTRIX systems, if the exec () function fails but is able to locate the process
image file, the st_ atime field is not marked for update.

3.1.2.4

Errors - For the exec () functions, ULTRIX systems detect the conditions and
return the corresponding errno value for [ENOMEM].

3.2 Process Termination
3.2.1
3.2.1.2

3.2.2
3.2.2.2

Wait for Process Termination
Description - On ULTRIX systems, a process that is stopped by the process tracing
mechanism, ptrace(2), returns the octal value 177 to either wai t () or
wai tpid (). Children of a terminated process are assigned the ini t process
(process id (Pid) = 1) as their new parent process.

Terminate a Process
Description - On ULTRIX systems, children of a terminated process are assigned
the ini t () process (process id (Pid) = 1) as their new parent process.
The sending of a SIGCHLD signal to the parent process is supported.
On ULTRIX systems, _POSIX_JOB_CONTROL is supported. When the exit ofa
process causes a process group to become orphaned and any member of the newlyorphaned process group is stopped, a SIGHUP signal, followed by a SIGCONT
signal, is sent to each process in the newly-orphaned process group.

3.3 Signals
3.3.1

Signal Concepts

3.3.1.1

Signal Names - The following additional signals occur in ULTRIX systems. For a
complete description of the default actions, refer to POSIX.I.
The values for the default actions are as follows:
•

1 = Abnormal termination of the process

•

2 = Ignore the signal

Symbolic
Constant
SIGTRAP
SIGIOT
SIGEMT
SIGBUS
SIGSYS
SIGURG
SIGIO
SIGXCPU
SIGXFSZ
SIGVTALRM
SIGPROF

3-2 Process Primitives

Default
Action
I
1
1
1
1

2
2
1
1
1
1

Generating Condition
Trace trap
lOT instruction
EMT instruction
Bus error
Bad argument to a system call
Urgent condition present on socket
I/O is possible on a descriptor
CPU time limit exceeded
File size limit exceeded
Virtual time alarm
Profiling timer alarm

Symbolic
Constant
SIGWINCH
SIGLOST

3.3.1.2

Default
Action
2
1

Generating Condition
Window size change
Lock not reclaimed after server recovery

Signal Generation and Delivery - On ULTRIX systems, a subsequent occurrence
of a pending signal does not cause the signal to be delivered more than once.
On ULTRIX systems, each signal has an associated integer value. In the case of
multiple simultaneous pending signals, the pending signal with the lowest associated
integral value is handled first.
The additional signals supported by ULTRIX systems are generated under the
conditions indicated in Section 3.3.1.1 of this document.

3.3.1.3

Signal Actions - On ULTRIX systems, if a process ignores a SIGFPE, SIGILL, or
SIGSEGV signal that was not generated by the kill () system call or the
r a is e () function as defined in the C Standard, the signal is ignored.
If a process sets the action for the SIGCHLD signal to SIG_IGN, the signal is
ignored.

On ULTRIX systems, if a process returns normally from a signal-catching function
for a SIGFPE, SIGILL, or SIGSEGV signal that was not generated by the ki 11 ( )
system call or the r a is e () function as defined by the C Standard, the process
continues executing.
If a process establishes a signal-catching function for the SIGCHLD signal while it
has a terminated child process for which it has not waited, a SIGCHLD signal is
generated to indicate that the child process has terminated.

3.3.2
3.3.2.2

Send a Signal to a Process
Description - On ULTRIX systems, the kill () system call takes two arguments,
pid and sig. The pid is the process ID of the process that is to receive the signal sig .
On ULTRIX systems, system processes are not affected by signals from
kill (-1, sig) or kill (0, sig). System processes are defined as any process whose
parent pid is equal to zero. This includes the following processes:
•

Initialization (process ID = 1)

•

Swapper (process ID =0)

•

Pager (process ID = 2)

If the effective user ID of a receiving process is altered through the use of the
S_ISUID mode bit, ULTRIX does not permit the application to receive a signal sent
by the parent process or by a process with the same real user ID.
If the pid is zero, the sig is sent to all processes whose process group ID is equal to
the proces~ group ID of the sender and for which the process has permission to send
a signal, excluding system processes. On ULTRIX systems, no process that is not a
system process can have a pid of less than 100.
Process Primitives 3-3

If the pid is -1 and the user is running as root (user ID = 0), the sig is sent to all
processes, except system processes.

3.3.3

Manipulate Signal Sets

3.3.3.4

Errors - For the sigaddset ( ) , sigdelset ( ) , and sigismernber ( )
functions, ULTRIX systems detect the conditions and return the corresponding errno
value for [EINVAL].

3.3.5

Examine and Change Blocked Signals

3.3.5.2

Description - On ULTRIX systems, if any of the SIGFPE, SIGILL, or SIGSEGV
signals are generated while they are blocked, unless the signal was generated by a
call to the kill () system call or the r a i s e () function as defined by the C
Standard, the signal is blocked.

3.3.6

Examine Pending Signals

3.3.6.4

Errors - For the sigpending () system call, ULTRIX systems detect when the
argument to sigpending () points to memory that is not a valid part of the
process address space and return the errno value [EFAULT].

3.4 Timer Operations
3.4.3

Delay Process Execution

3.4.3.2

Description - The sleep () function establishes a signal handler for SIGALRM.
Therefore, the SIGALRM signal cannot be ignored or blocked during the execution
of the s 1 e ep () function.
If a SIGALRM signal is generated for the calling process during execution of the
sleep () function, except as a result of a prior call to the alarm () function,
sleep () returns the amount of unslept time.
If a signal-catching function interrupts the sleep () function and examines or
changes the time a SIGALRM is scheduled to be generated, the action associated
with the SIGALRM signal, or whether the SIGALRM signal is blocked, sleep ( )
returns the amount of unslept time. All caught signals cause sleep () to terminate.
If a signal-catching function interrupts the sleep () function and calls the
siglongjmp () or longjmp () function to restore an environment saved prior to
the sleep () call, the action associated with the SIGALRM signal and the time at
which a SIGALRM signal is scheduled to be generated are as follows:

3-4 Process Primitives

•

The time at which the SIGALRM signal is scheduled is that time set by the
signal catching function.

•

The action associated with the SIGALRM signal is the action set by the signal
catching function.

The longjrnp () function restores the process's signal mask as part of the
environment.

Process Primitives 3-5

Process Environment

This chapter describes the process environment for ULTRIX systems.

4.2 User Identification
4.2.3
4.2.3.2

Get Supplementary Group IDs
Description - On ULTRIX systems, the effective group 10 of the calling process is
included in the returned list of supplementary group IDs.

4.2.4 Get User Name
4.2.4.3

Returns - On ULTRIX systems, the return value from getlogin () points to
static data.
On ULTRIX systems, if eu s e rid () is called with a NULL pointer, the return
value from euserid () points to static data.
On ULTRIX systems, the euserid () function does not use the getpwnam ( )
function, but does use getpwuid ( ). Thus, a call to euserid () will overwrite
the data returned by previous calls to getpwnam ( ) .

4.2.4.4

Errors - There are no implementation-defined error conditions for the
getlogin () and euserid () functions.

4.4 System Identification
4.4.1
4.4.1.2

System Name
Description - On ULTRIX systems, the struct utsname returned by uname ( )
contains the following members, formats, and (optional) ranges of values:

4.4.1.4

Member Name

Format

Range

sysname

string

"ULTRIX"

nodename

string

The nodename field
is initialized upon
the first call to
uname() from the
hostname field

release

string

"4.0"

version

string

"0"

machine

string

"VAX" or "RISe"

Errors - On ULTRIX systems, the uname () system call fails if the name argument
points to an invalid address. In such instances, errno is set to [EFAULT] when the
call returns.

4.5 Time
4.5.1
4.5.1.4

Get System Time
Errors - On ULTRIX systems, for the time () function, no error conditions are
detected.
On ULTRIX systems, if the tloc argument to the time () function is not NULL, the
time () function tries to use it.

4.5.2

Process Times

4.5.2.3

Returns - On ULTRIX systems, the return value for the time s () function can
overflow the possible range of type clock_to

4.5.2.4

Errors - On ULTRIX systems, no error conditions are detected for the times ()
function.

4.6 Environment Variables
4.6.1

Environment Access

4.6.1.3

Returns - The return value for getenv () does riot point to static data.

4-2 Process Environment

4.6.1.4

Errors - There are no implementation-defined error conditions for the getenv ( )
function.

4.7 Terminalldentification
4.7.1

Generate Terminal Pathname

4.7.1 .3

Retu rns - If the parameter to c t e rmi d () is NULL, the return value is in a static
data area.

4.7.1.4

Errors - There are no implementation-defined error conditions for the ctermid ( )
function.

4.7.2

Determine Terminal Device Name

4.7.2.2

Description - On ULTRIX systems, the return value of ttyname () points to
static data.

4.7.2.3

Errors - On ULTRIX systems, there are no implementation-defined error conditions
for the ttyname () or the isatty () function.

4.8 Configurable System Variables
4.8.1

Get Configurable System Variables

4.8.1.2

Description - On ULTRIX systems, additional system configurable variables
beyond those listed in Table 4-2 of POSIX.l are supported. These variables and the
values from <unistd. h> used as the name argument to the sysconf () function
are shown in the following table:

Variable

Description

name value

{PASS_MAX}

Maximum number of
characters in a
password (not
including terminating
nUll)

{_SC_PASS_MAX}

{_XOPEN_VERSION}

Integer value
indicating the
version of XPG to
which the system is
compliant

{_SC_XOPEN_VERSION}

Process Environment 4-3

Files and Directories

This chapter describes the functions that ULTRIX systems use for file and directory
manipulation.

5.1

Directories

5.1.1

Format of Directory Entries
On ULTRIX systems, a directory is represented by a file-like inode. A directory and
regular file inode are differentiated by the mode field in the inode. The data portion
of a directory points to directory structures. The format of a directory entry is
described by the struct dirent in the system header file <s y s / di r . h>. For more
information, refer to dir(5) in the ULTRIX Reference Pages.
The character array d_name can contain a maximum of 256 bytes.

5.1.2

Directory Operations

5.1.2.2

Description - On ULTRIX systems, the pointer returned by readdir () points to
data that is overwritten by a subsequent call to readdir () on the same directory
stream. Overwriting occurs when the number of entries buffered by readdir () is
exhausted and the next set of entries is read by the function.
The readdir () function can buffer several directory entries for each actual read
operation.
On ULTRIX systems, if the dirp argument passed to any of the file operation
functions does not refer to a currently open directory stream, the function fails and
errno is set to [EBADF].
On ULTRIX systems, after a call to the for k () function, if both the parent and
child processes use the readdir () or rewinddir () function, each effects the
other's offset of the directory being operated on through the function calls.

5.1.2.4

Errors - For the opendir () function, ULTRIX systems detect the conditions and
return the corresponding errno values for [EMFILE] and [ENFILE].
For the readdir () function, ULTRIX systems detect the conditions and return the
corresponding errno value for [EBADF].
For the closedir () function, ULTRIX systems detect the conditions and return
the corresponding errno value for [EBADF].

5.2 Working Directory
5.2.2
5.2.2.2

Working Directory Pathname
Description - On ULTRIX systems, if the buf argument to getcwd (buf, siz) is a
NULL pointer, the getcwd () directory obtains size bytes of space using
malloc ( ). The pointer returned by getcwd () can be used as the argument to a
subsequent call to free ( ) .

5.2.2.3

Returns - On ULTRIX systems, after an error on a call to get cwd () is returned,
the current contents of buf are undefined.

5.2.2.4

Errors - For the get cwd () function, ULTRIX systems detect the conditions and
return the corresponding errno value for [EACCES].

5.3 General File Creation
5.3.1

Open a File

5.3.1.2

Description - On ULTRIX systems, if the O_RDWR flag is set in oflag and open
(path, oflag, mode) is called to open a FIFO, the file descriptor returned by open ( )
can be used for reading and writing bytes to and from the FIFO.

On ULTRIX systems, when the 0_CREAT flag is set in oflag and when bits in mode
other than the file permission bits are set, the file is created with the mode bits that
remain after the mode argument is masked against the process's file creation mask.
On ULTRIX systems, if the O_EXCL bit is set and O_CREAT is not set, the
O_EXCL bit is silently ignored and the open () is attempted. If the file does not
exist, it will not be created, resulting in open () returning an error.
On ULTRIX systems, the O_NONBLOCK flag in the path parameter is ignored
unless the path parameter refers to a block or character special file or the path
parameter refers to a FIFO special file and the O_RDONLY or the 0_WRONLY flag
is also set in oflag.
If the O_TRUNC bit is set in oflag and path resolves to a socket or character or
block special file, the result is an access check for write privileges.
On ULTRIX systems, using O_TRUNC with O_RDONLY has the following effect:
if the process has write access, the file is truncated to a size of zero.

5.3.3

Set File Creation Mask

5.3.3.2

Description - On ULTRIX systems, if you specify invalid permission bits to the
umask () function, it sets the file creation mask of the process to valid file
permission bits by ignoring the invalid bits. The valid bits are defined to be those
corresponding to the bitwise inclusive OR of S_IRWXU, S_IRWXG, and
S_IRWXO.

5-2 Files and Directories

5.3.4

Link to a File

5.3.4.2

Description - On ULTRIX systems, links across file systems are not valid. If you
attempt such an operation, the link system call returns a value of -1 with errno set to
[EXDEV].
On ULTRIX systems, the linking of directories is not supported through the
link () function.
The calling process does not require read, write, or execute permission on the file
being linked. However, the calling process must have search permission on the parent
directory of the file.

5.4 Special File Creation
5.4.1

Make a Directory

5.4.1.2

Description - On ULTRIX systems, the mode argument to mkdir (path, mode) is
masked against the process's file creation mask set by uma s k ( ). This masking
results in the directory being created with a valid mode.

5.4.2

Make a FIFO Special File

5.4.2.2

Description - On ULTRIX systems, the mode argument to the mk f i fa ( )
function is masked against the process's file creation mask set by uma s k ( ). This
results in a FIFO special file being created with a valid mode.

5.5 File Removal
5.5.2

Remove a Directory

5.5.2.2

Description - On ULTRIX systems, when the root directory or the current working
directory of a process is removed, the process holds a pointer to its current working
directory. Because ULTRIX systems do not release the space allocated to a directory
until all references are gone, there is no effect for the process when the root or
current working directory is removed. Other processes will not be able to access the
directory, however.
On ULTRIX systems, a directory can be removed only if it is empty.

5.5.3

Rename a File

5.5.3.2

Description - On ULTRIX systems, in a call to rename (old, new), if the old
argument points to the pathname of a directory, write access permission is not
required for the directory named by old; if the directory named by new exists, write
permission for the directory is not required.

Files and Directories 5-3

5.6 File Characteristics
5.6.1

File Characteristics: Header and Data Structure

5.6.1.2

The <sys/stat. h> File Modes - On ULTRIX systems, there are no additional
bits logically ORed with S_IRWXU, S_IRWXG, and S_IRWXO.

5.6.1 .3

The < s y s / s tat. h> Time Entries - ULTRIX systems do not change the timerelated fields of struct stat by any functions other than those described in POSIX.l.

5.6.2

Get File Status

5.6.2.2

Description - If the access control methods described in POSIX.l are honored,
ULTRIX systems cannot deny the existence of the file.

If the file does not exist, errno is set to [ENOENTJ when the call returns.

5.6.3

File Accessibility

5.6.3.2

Description - If a process has appropriate privileges, access (path, X_OK)
returns a zero whether or not execute permission bits are set for path.

5.6.3.4

Errors - For the access () function, ULTRIX systems detect the conditions and
return the errno value for [EINVALJ.

5.6.4

Change File Modes

5.6.4.2

Description - On ULTRIX systems, the S_ISUID and S_ISGID bits on file systems
that have been mounted with the nosuid option set are ignored.
On ULTRIX systems, changes made through the chmod () function do not effect
file descriptions for files that are currently open.

5.6.5

Change Owner and Group of a File

5.6.5.2

Description - On ULTRIX systems, calls to chown () from a process with
appropriate privileges do not clear the S_ISUID and S_ISGID bits.

5.6.5.4

Errors - For the chown 0 function, ULTRIX systems detect the conditions and
return the errno value for [EINVALJ.

5-4 Files and Directories

5.7 Configurable Pathname Variables
5.7.1

Get Configurable Pathname Variables

5.7.1.2

Description - ULTRIX systems do not support any additional variables, beyond
those listed in Table 5-2 of POSIX.1, that can be queried by the pathconf () and
fpathconf () functions.
ULTRIX systems do not need to use the path or fildes arguments. Therefore, the
return value is not effected by the type of file the argument refers to.

5.7.1.4

Errors - For the pathconf () function, ULTRIX systems detect the conditions
and return the corresponding errno values for [EACCES], [EINVAL],
[ENAMETOOLONG], [ENOENT], and [ENOTDIR].
For the fpathconf () function, ULTRIX systems detect the conditions and return
the corresponding errno values for [EBADF] and [EINVAL].

Files and Directories 5-5

Input and Output Primitives

This chapter provides a brief explanation of the input and output functions and the
control operations of ULTRIX systems.

6.4 Input and Output
6.4.1

Read from a File

6.4.1.2

Description - For a device special file, ULTRIX systems handle subsequent read
operations in the same way they handle read operations to a file.
If a read to any kind of file is interrupted after a data transfer and some data was
successfully read before the interrupt, the read () function returns the number of
bytes read before the interrupt.
If the value of nbyte is greater than {INT_MAX}, a zero is returned.
If the device is incapable of seeking (for example, a tenninal device), the concept of
a file offset is not applicable. Subsequent reads will start from the current position in
the file.

A read fails with errno set to [EINVAL] if the count is greater than {INT_MAX}.

6.4.1.4

Errors - On ULTRIX systems, an [EIO] error is generated if an I/O error occurs
while reading from the file system.

6.4.2
6.4.2.2

Write to a File
Description - On ULTRIX systems, if a write of zero bytes to a file that is not a
regular file is attempted, the system ignores the write.
If a write to any kind of file is interrupted after a data transfer and the data was
successfully written before the interrupt, the wri te () function returns the number
of bytes written before the interrupt.

A write fails with errno set to [EINVAL] if nbyte is greater than {INT_MAX} .

6.4.2.4

Errors - On ULTRIX systems, the maximum file size is 264-1 bytes. If the size of a
file exceeds this limit, write () returns a value of -1 with errno set to [EFBIG].

6.5 Control Operations on Files
6.5.2

File Control

6.5.2.2

Description - ULTRIX systems support additional file status flags beyond those
listed in POSIX.1 Table 6-5. See fcntl(2) in the ULTRIX Reference Pages for a
complete list of the file status flags. If the fcntl () function is called with the cmd
argument set to F_SETFL and if any bits are set in arg other than those listed in the
fcntl(2) reference page, the invalid file status bits are ignored and the file status
flag is set to the valid flags passed through arg.
ULTRIX systems support advisory locking on regular, special device, and socket file
types.
ULTRIX systems support a negative I_len member of struct flock. The user must
already own the lock. The fcntl () function subtracts the absolute value of I_len
from the previous start and sets the length of the lock to the absolute value of I_len.

6.5.2.4

Errors - For the fcntl () function, ULTRIX systems detect the conditions and
return the errno value for [EDEADLK].

6.5.3

Reposition ReadlWrite File Offset

6.5.3.2

Description - On ULTRIX systems, when the lseek () function is performed on
a file that is incapable of seeking, three possible events can occur:
•

The function returns a file offset that is never used.

•

The function returns a value of -1 with errno set to [ESPIPE] if the file
descriptor describes a pipe.

•

The function returns -1 with errno set to [EBADF] if the file descriptor
describes a file in the file system.

6-2 Input and Output Primitives

Device- and Class-Specific Functions

This chapter describes the interface characteristics and control functions of ULTRIX
systems.

7.1

General Terminal Interface
ULTRIX systems support asynchronous terminals and network terminals, using the
General Terminal Interface defined in POSIX.l, through the use of pseudoterminals.
Synchronous ports are not supported by the same interface. For a complete
description of the terrnios interface, refer to terrnios(4) in the ULTRIX
Reference Pages.

7.1.1

Interface Characteristics

7.1.1.3

The Controlling Terminal - On ULTRIX systems, if a session leader has no
controlling terminal and opens a terminal device file that is not already associated
with a session without using the open function's O_NOCTTY option, the terminal
becomes the controlling terminal of the session leader.

7.1.1.5

Input Processing and Reading Data - ULTRIX systems impose the limit
MAX_INPUT on the number of bytes that can be stored in the input queue.
When ICANON is not set by an application and if the character input buffers of the
system become full, the system flushes the input buffer without notice. This action
causes all the characters in the input queue to be lost. If an application sets ICANON
and the character input buffers of the system become full, the driver discards
additional characters and echoes a bell (ASCII BEL) to notify the user of the full
condition.

7.1.1.6

Canonical Mode Input Processing - When there are MAX_CANON characters
in an input line, additional characters are discarded.

7.1.1.7

Non-Canonical Mode Input Processing - On ULTRIX systems, the value of
MIN cannot exceed MAX_INPUT because the value is placed in an unsigned
character type and MAX_INPUT is equal to UCHAR_MAX.

7.1.1.8

Writing Data and Output Processing - On ULTRIX systems, the terminal
interface provides a buffering mechanism. For example, when a call to wri te ( )
completes, all of the characters written have been scheduled for transmission to the
device, but the transmission is not necessarily complete. The characters are
transmitted to the device as soon as previously written characters have been output
successfully.

7.1.1.9

Special Characters - On ULTRIX systems, the values for the START and STOP
characters can be set by the user. There are no multibyte sequences with different
meanings from the meaning of the bytes when considered individually.
ULTRIX systems define the following single-byte functions:

Function

Character

Effect

VLNEXT
VFLUSH
VWERASE
VRPRNT
VDSUSP

CTRLN
CTRL/O
CTRL/W
CTRL/R
CTRL/Y

Next character is literal
Toggle output discarding
Erase previous word
Reprint line
Delayed suspend character

7.1.2

Settable Parameters

7.1.2.1

The termios Structure - On ULTRIX systems, the termios structure is defined in
the header <termios . h>. The members of this structure are shown as folows:
struct termios {
tcflag_t
c_iflag
tcflag_t
c_oflag
tcflag_t
c_cflag
tcflag_t
c_lflag
cc_t
c - cc[NCCS]
cc_t
c line;
}

/*
/*
/*
/*
/*
/*

input modes
output modes
control modes
local modes
control chars
line discipline

*/
*/
*/
*/
*/
*/

The types tcflag t (unsigned long) and cc t (unsigned char) are defined in the header
<termios . h>-:- The value of NCCS is 19 and is defined in <termios . h>.
The total size of the termios structure is 36 bytes.

7.1.2.2

Input Modes - When an application sets ICANON, if the number of characters
input exceeds (MAX_INPUT/2) and if the number of characters in the canonical
input queue exceeds (MAX_INPUT/3), the system transmits a STOP character. The
system transmits a START character when the number of characters in the canonical
input queue drops below (MAX_INPUT/5).
If an application does not set ICANON and if the number of input characters exceeds
(MAX_INPUT/2), the system transmits a STOP character. The system transmits a
START character when the number of characters in the input queue drops below
(MAX_INPUT/5).

After an application opens a terminal line, the initial input control value is zero (all
settings off).
It is not possible to generate a break condition on network pseudoterminals.

7.1.2.3

Output Modes - After an application opens a terminal line, the initial output
control value is zero (all settings off).

7-2 Device- and Class-Specific Functions

Additional output control values have been defined. These attributes are used when
OPOST is set. For a complete description of output modes, refer to termios(4) in
the ULTRIX Reference Pages.

7.1 .2.4

Control Modes - The terminal subsystem of ULTRIX systems only supports
asynchronous terminals.
On ULTRIX systems, the initial hardware control values after open () are CS8,
CREAD, B300, and RUPCL.

7.1.2.5

Local Modes - If ECROE and ICANON are set and the ERASE character attempts
to erase when there is no character to erase, ULTRIX systems do not echo anything.
If ECHOK and ICANON are set, the KILL character echoes a newline ( '\ n' )
character after the KILL character. If ECROE and ICANON are turned on and there
are no characters to erase, a newline is echoed. If there are characters to erase from
the line and ECHOE and ICANON are set, the characters are erased from the display.

The IEXTEN flag enables additional special control characters.
IEXTEN being set interacts with ICANON, ISIG, IXON, or IXOFF.
After an application opens a terminal line, the initial local control value is zero
(all settings off). Additional local control values have been defined. For a complete
list of local modes and their interactions with other values, refer to termios(4) in
the ULTRIX Reference Pages.

7.1.2.6

Special Control Characters - The number of elements in the c_cc array, NCCS,
is 19.
On ULTRIX systems, additional special control characters have been defined. These
special control characters are used only when the IEXTEN flag is set. For a complete
list of special control characters, refer to termios(4) in the ULTRIX Reference
Pages.
ULTRIX systems support setting of the START and STOP characters.

Device- and Class-Specific Functions 7-3

The following table shows the octal default values for the special characters:

Special Character

Octal Value

VINTR
VQUIT
VERASE
VKILL
VEOF
VEOL
VMIN
VTIME
VSTART
VSTOP
VSUSP

177
034
043
100
004
377
006
001
021
023
032

7.1.2.7

Baud Rate Functions

7.1.2.7.2

Description - On ULTRIX systems, attempts to set unsupported baud rates are
ignored. The functions cfsetispeed ( ), cfsetospeed ( ), and
tcsetattr () do not return errors in response to unsupported baud rates. It is
possible to set input and output baud rates to different values.

7.1.2.7.4

Errors - For the functions cfsetispeed () and cfsetospeed ( ), ULTRIX
systems do not detect error conditions.
A call to tcgettattr ( ), then a call to cfgetispeed () or cfgetospeed ()
should be made to verify that the baud rate was set after a call to t c set at t r ( ) .

7.2 General Terminal Interface Control Functions
7.2.2

Line Control Functions

7.2.2.2

Description - ULTRIX systems support the following types of terminal devices:
•

Asynchronous

•

Pseudoterminal

•

LAT (local area transport protocol)

On ULTRIX systems, if the duration passed to the tcsendbreak () function is
greater than zero, zero-valued bits will be transmitted for (duration*.Ol) seconds.
If the object referred to by fildes is a pseudoterminal, no break is generated.

7-4 Device- and Class-Specific Functions

7.2.3

Get Foreground Process Group 10

7.2.3.2

Description - ULTRIX systems define _POSIX_JOB_CONTROL. The
tcgetpgrp () function is supported.

7.2.4

Set Foreground Process Group 10

7.2.4.2

Description - ULTRIX systems define _POSIX_JOB_CONTROL. The
tcsetpgrp () function is supported.

Device- and Class-Specific Functions 7-5

Language-Specific Services for the C
Programming Language

This chapter provides C programming language conformance statements and
describes language specific services for ULTRIX systems.

Conformance
Implementation Conformance
ULTRIX systems conform to C Language Binding (Common Usage C Language
Dependent System Support) on all systems using the default C compiler. In order to
select the POSIX versions of the library routines, compilation and linking commands
must either specify the -YPOSIX option, or the environment variable PROG ENV
must have the value POS IX with no conflicting - Y option. For additional information, refer to the Guide to Languages and Programming.

8.1

Referenced C Language Routines
All functions listed in Section 8.1 are implemented as specified by the C Standard.

8.1.1

Extensions to Time Functions
On ULTRIX systems, the environment variable TZ uses the format in which the first
character is a colon (:) and the characters that follow the colon are interpreted as the
pathname of a t z f i 1 e () format file. This file provides the time conversion
information. If the pathname begins with a slash (/), it represents an absolute
pathname; otherwise the pathname is relative to the system time conversion
information directory / etc/ zoneinfo. For further information, see ctime(3) in
the ULTRIX Reference Pages.

8.1.2

Extensions to the set locale Function

8.1.2.2

Description - On ULTRIX systems, the default locale is based on 7-bit US-ASCII
with strings in American English and date formats according to the American
definition. Called the C locale, it is the system default locale for the following
environment variables:

Environment Variable
LC_TYPE
LC_COLLATE
LC_TlME
LC_NUMERIC
LC_MONETARY
LANG

Default Value
C
C
C
C
C
C

On ULTRIX systems, if the specified LC_* environment variable is not set or if it is
set to the empty string, set locale () examines the LANG environment variable.
If LANG is set to the name of a valid locale, that value is used at runtime to set the
program locale. Otherwise, set locale () returns a NULL pointer and does not
change the locale. For further information, refer to the Guide to Developing
International Software. For further information on setlocale(3int), refer to the
ULTRIX Reference Pages.

8.2 FILE-Type C Language Functions
8.2.1

Map a Stream Pointer to a File Descriptor

8.2.1.4

Errors - On ULTRIX systems, there are no implementation-defined error conditions
for the fileno () function.

8.2.2

Open a Stream on a File Descriptor

8.2.2.2

Description - On ULTRIX systems, the type argument to the fdopen () function
contains the following additional values:

8.2.2.4

•

"A"

Synonym for "a"

•

"A+"

Synonym for "a+"

Errors - There are no implementation-defined error conditions for the f dopen ( )
function.

8.3 Other C Language Functions
8.3.2

Set Time Zone

8-2 Language-Specific Services for the C Programming Language

8.3.2.2

Description - On ULTRIX systems, if the environment variable TZ is absent, the
file / etc/ zoneinfo/ local time is used to obtain time conversion information.
If retrieving the information from this file fails for any reason, the Greenwich Mean
Time (GMT) offset as provided by the kernel is used. For further information, see
ct ime(3) in the ULTRIX Reference Pages.

Language-Specific Services for the C Programming Language 8-3

System Databases

This chapter provides information on system databases and database access for
ULTRIX systems.

9.1 System Databases
On ULTRIX systems, if the home directory field in the user database is null, the root
directory (I) is used as the home directory.

9.2 Database Access
9.2.1
9.2.1.2

Group Database Access
Description - The getgrgid () and getgrnam () functions both return a
pointer to an object of type struct group that contains an entry from the group
database with a matching gid or name. This structure includes the members shown
in the following table. In addition to the group database fields specified in Section
9.1 of POSIX.l, the group database on ULTRIX systems contains the gryasswd
field (encrypted password).

9.2.1.3

Member
Type

Member
Name

Description

char *

gr_name

char *

gryasswd

gid_t

gr_gid

char **

gr mem

The name of the
group
The encrypted
password for the
group
The numerical group
ID
A null-terminated
vector of pointers to
the individual
member names

Returns - The return value of the getgrgid () function points to a static data
area and will be overwritten by subsequent calls. This static area is also used by the
functions getgrent () and getgrnam ( ). A call to anyone of these functions
overwrites any data contained in the static area.

9.2.1.4

Errors - There are no implementation-defined error conditions for the
getgrgid () or the getgrnam () function.

9.2.2

User Database Access

9.2.2.2

Description - On ULTRIX systems, the getpwuid () and getpwnam ( )
functions both return a pointer to an object of type struct passwd containing an entry
from the user database with a matching uid or name.
This structure includes the members shown in the following table. In addition to the
user database fields specified in Section 9.1 of POSIX.1, the ULTRIX user database
contains three additional fields: pw_quota, pw_comment, and pw_gecos .

Member

Type

Name

char *
char *

pw_name
pwyasswd

uid t
gid t
int
char *
char *
char *

pw uid
pw_gid
pw_quota
pw_comment
pw_gecos
pw_dir

char *

pw shell

Description
User's login name
User's encrypted
password
User ID number
Group ID number
Unused
Unused
User description
Initial working
directory
Initial user program

The cuserid () function uses the getpwuid () function and overwrites data in
the static area on subsequent calls.

9.2.2.3

Returns - The getpwuid () and getpwnam () functions return values to the
static data area and overwrite data in this area on each subsequent call.

9.2.2.4

Errors - There are no implementation-defined error conditions for the
getpwuid () or getpwnam () function.

9-2 System Databases

Data Interchange Format

This chapter contains information on the tar and epio file formats on ULTRIX
systems.

10.1 Archive/Interchange File Format
On ULTRIX systems, the format-reading and format-creating utilities are named tar
and epio. For a description of these utilities and the interfaces to them, refer to
tar(l) and epio(1) in the ULTRIX Reference Pages.

10.1.1

Extended tar Format
On ULTRIX systems, the tar utility by default groups twenty 512-byte blocks into
a record for physical I/O operations.
On ULTRIX systems, the tar utility by default writes a group of twenty 512-byte
blocks in a single wr i t e () operation.
In the typeflag field of the header used by the tar utility, the ASCII digit ' 7' is
reserved to indicate some high-performance attribute.
On ULTRIX systems, if a file name is found on the medium that would create an
invalid file name on the system, the data from the file is not stored on the file
hierarchy. The tar utility ignores such files and produces an error message ("Can't
create... ") indicating that the file is being ignored.
On ULTRIX systems, the tar utility terminates if mode bits that are not defined in
POSIX.l are encountered in the mode field.
On ULTRIX systems, if the typeflag field is CHARTYPE, BLKTYPE, or
FIFOTYPE, the size field is set to zero and is not used.
On ULTRIX systems, all characters are valid for use in file names. For character and
block special file types, the devmajor and devminor fields contain the major and
minor device numbers as used by the local system.

10.1.2

Extended cp i 0 Format
On ULTRIX systems, the ep i 0 utility writes a series of fixed size blocks of bytes in
a POSIX conformant manner.

10.1.2.1

Header - On ULTRIX systems, the ep i 0 header values c_dev , c_ino , and c_rdev
for a particular file are obtained from the information returned by the s tat system
call in the fields st_dev, st_ino, and st_rdev, respectively.
For character or block special files, c_rdev contains the major and minor numbers of
the device the file describes.

10.1.2.2

File Name - On ULTRIX systems, the ep i 0 utility supports the use of the POSIX
portable filename character set.
When an ULTRIX system finds a file name on a medium that would create an invalid
file name, it issues an error message ("Can't create ... "), skips the file, and processes
the next file in the archive.

10.1.2.4

Special Entries - On ULTRIX systems, the cJzlesize parameter is not defined for
device special files. For other special files (FIFOs, sockets, directories, and so on),
cJzlesize is set to the size of the archived file.

10.1.2.5

The epio Values - On ULTRIX systems, the epio command supports some
special file types as defined by PO SIX. 1. These include sockets (C_ISSOCK), links
(C_ISLNK), character special files, and block special files.
POSIX.l reserves C_ISVTX, C_ISCTG, C_ISLNK, and C_ISSOCK to retain
compatability with some existing implementations.
On ULTRIX system, the epio utility ignores mode flags in the archive that are not
mentioned in POSIX.l.

10.1.3

Multiple Volumes
On ULTRIX systems, the epio command supports archive save sets that span
multiple volumes. The user is prompted to mount the next volume of an archive
when ep i 0 determines the next volume is needed. The next volume must be
mounted on the same physical device as the initial volume. That is, if initially
reading from / dev / rmt 0 h, all subsequent volumes must be mounted on
/ dev /rmtOh.

10-2 Data Interchange Format

POSIX FIPS Additional Requirements

The ULTRIX Version 4.0 Operating System meets the requirements specified by the
POSIX Federal Information Processing Standard (PIPS 151-1). This appendix is a
reproduction of these requirements. Note that the base document for FIPS 151-1 is
IEEE Std 1003.1-1988.
The following modifications to IEEE Std 1003.1-1988, IEEE Standard Portable
Operating System Interface for Computer Environments, are required for
implementations of POSIX that are acquired by Federal agencies:
•

Inconsistencies with CLK_TCK exist between the IEEE Std 1003.1-1988 and
the referenced ANSI/X3.159-1989 Programming Language C Standard draft 13
May 1988 (X3Jl1/88-002). This inconsistency shall be resolved in the ratified
C Standard. Until the C Standard is ratified, CLK_TCK is to be treated as a
PO SIX-only symbol.

•

The implementation shall support the option
_POSIX_CHOWN_RESTRICTED.

•

The implementation shall support the option {NGROUPS_MAX} such that the
value of {NGROUPS_MAX} is greater than or equal to eight (8).

•

The implementation shall support the setting of the group-ID of a file (when it
is created) to that of its parent directory.

•

The implementation shall support the functionality associated with the feature
{_POSIX_SAVED_IDS}.

•

The implementation shall support the functionality associated with the feature
{_POSIX_VDISABLE}.

•

The implementation shall support the option _POSIX_JOB_CONTROL.

•

The implementation shall support the functionality associated with the feature
{_POSIX_NO_TRUNC}.

•

In section 6.4.1.2, the sentence "If a read () is interrupted by a signal after it
has successfully read some data, either it shall return -1 with errno set to
[EINTR], or it shall return the number of bytes read." shall be deleted and
replaced with the sentence "If a read () is interrupted by a signal after it has
successfully read some data, it shall return the number of bytes the system has
read."

In section 6.4.2.2, the sentence "If a wri te () is interrupted by a signal after it
successfully writes some data, either it shall return -1 with errno set to [EINTR], or it
shall return the number of bytes written." shall be deleted and replaced with the
sentence "If a wri te () is interrupted by a signal after it successfully writes some
data, it shall return the number of bytes the system has written."
•

The environment for the login shell shall contain the environment variables
HOME and LOGNAME as defined in section 2.7.

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