PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

LP(1P)                    POSIX Programmer's Manual                   LP(1P)

PROLOG         top

       This manual page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior), or
       the interface may not be implemented on Linux.

NAME         top

       lp — send files to a printer

SYNOPSIS         top

       lp [−c] [−d dest] [−n copies] [−msw] [−o option]... [−t title] [file...]

DESCRIPTION         top

       The lp utility shall copy the input files to an output destination in
       an unspecified manner. The default output destination should be to a
       hardcopy device, such as a printer or microfilm recorder, that
       produces non-volatile, human-readable documents. If such a device is
       not available to the application, or if the system provides no such
       device, the lp utility shall exit with a non-zero exit status.

       The actual writing to the output device may occur some time after the
       lp utility successfully exits. During the portion of the writing that
       corresponds to each input file, the implementation shall guarantee
       exclusive access to the device.

       The lp utility shall associate a unique request ID with each request.

       Normally, a banner page is produced to separate and identify each
       print job. This page may be suppressed by implementation-defined
       conditions, such as an operator command or one of the −o option
       values.

OPTIONS         top

       The lp utility shall conform to the Base Definitions volume of
       POSIX.1‐2008, Section 12.2, Utility Syntax Guidelines.

       The following options shall be supported:

       −c        Exit only after further access to any of the input files is
                 no longer required. The application can then safely delete
                 or modify the files without affecting the output operation.
                 Normally, files are not copied, but are linked whenever
                 possible. If the −c option is not given, then the user
                 should be careful not to remove any of the files before the
                 request has been printed in its entirety. It should also be
                 noted that in the absence of the −c option, any changes
                 made to the named files after the request is made but
                 before it is printed may be reflected in the printed
                 output.  On some implementations, −c may be on by default.

       −d dest   Specify a string that names the destination (dest).  If
                 dest is a printer, the request shall be printed only on
                 that specific printer. If dest is a class of printers, the
                 request shall be printed on the first available printer
                 that is a member of the class. Under certain conditions
                 (printer unavailability, file space limitation, and so on),
                 requests for specific destinations need not be accepted.
                 Destination names vary between systems.

                 If −d is not specified, and neither the LPDEST nor PRINTER
                 environment variable is set, an unspecified destination is
                 used. The −d dest option shall take precedence over LPDEST,
                 which in turn shall take precedence over PRINTER.  Results
                 are undefined when dest contains a value that is not a
                 valid destination name.

       −m        Send mail (see mailx(1p)) after the files have been
                 printed. By default, no mail is sent upon normal completion
                 of the print request.

       −n copies Write copies number of copies of the files, where copies is
                 a positive decimal integer. The methods for producing
                 multiple copies and for arranging the multiple copies when
                 multiple file operands are used are unspecified, except
                 that each file shall be output as an integral whole, not
                 interleaved with portions of other files.

       −o option Specify printer-dependent or class-dependent options.
                 Several such options may be collected by specifying the −o
                 option more than once.

       −s        Suppress messages from lp.

       −t title  Write title on the banner page of the output.

       −w        Write a message on the user's terminal after the files have
                 been printed. If the user is not logged in, then mail shall
                 be sent instead.

OPERANDS         top

       The following operand shall be supported:

       file      A pathname of a file to be output. If no file operands are
                 specified, or if a file operand is '−', the standard input
                 shall be used. If a file operand is used, but the −c option
                 is not specified, the process performing the writing to the
                 output device may have user and group permissions that
                 differ from that of the process invoking lp.

STDIN         top

       The standard input shall be used only if no file operands are
       specified, or if a file operand is '−'.  See the INPUT FILES section.

INPUT FILES         top

       The input files shall be text files.

ENVIRONMENT VARIABLES         top

       The following environment variables shall affect the execution of lp:

       LANG      Provide a default value for the internationalization
                 variables that are unset or null. (See the Base Definitions
                 volume of POSIX.1‐2008, Section 8.2, Internationalization
                 Variables for the precedence of internationalization
                 variables used to determine the values of locale
                 categories.)

       LC_ALL    If set to a non-empty string value, override the values of
                 all the other internationalization variables.

       LC_CTYPE  Determine the locale for the interpretation of sequences of
                 bytes of text data as characters (for example, single-byte
                 as opposed to multi-byte characters in arguments and input
                 files).

       LC_MESSAGES
                 Determine the locale that should be used to affect the
                 format and contents of diagnostic messages written to
                 standard error and informative messages written to standard
                 output.

       LC_TIME   Determine the format and contents of date and time strings
                 displayed in the lp banner page, if any.

       LPDEST    Determine the destination. If the LPDEST environment
                 variable is not set, the PRINTER environment variable shall
                 be used. The −d dest option takes precedence over LPDEST.
                 Results are undefined when −d is not specified and LPDEST
                 contains a value that is not a valid destination name.

       NLSPATH   Determine the location of message catalogs for the
                 processing of LC_MESSAGES.

       PRINTER   Determine the output device or destination. If the LPDEST
                 and PRINTER environment variables are not set, an
                 unspecified output device is used. The −d dest option and
                 the LPDEST environment variable shall take precedence over
                 PRINTER.  Results are undefined when −d is not specified,
                 LPDEST is unset, and PRINTER contains a value that is not a
                 valid device or destination name.

       TZ        Determine the timezone used to calculate date and time
                 strings displayed in the lp banner page, if any. If TZ is
                 unset or null, an unspecified default timezone shall be
                 used.

ASYNCHRONOUS EVENTS         top

       Default.

STDOUT         top

       The lp utility shall write a request ID to the standard output,
       unless −s is specified. The format of the message is unspecified. The
       request ID can be used on systems supporting the historical cancel
       and lpstat utilities.

STDERR         top

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES         top

       None.

EXTENDED DESCRIPTION         top

       None.

EXIT STATUS         top

       The following exit values shall be returned:

        0    All input files were processed successfully.

       >0    No output device was available, or an error occurred.

CONSEQUENCES OF ERRORS         top

       Default.

       The following sections are informative.

APPLICATION USAGE         top

       The pr and fold utilities can be used to achieve reasonable
       formatting for the implementation's default page size.

       A conforming application can use one of the file operands only with
       the −c option or if the file is publicly readable and guaranteed to
       be available at the time of printing. This is because POSIX.1‐2008
       gives the implementation the freedom to queue up the request for
       printing at some later time by a different process that might not be
       able to access the file.

EXAMPLES         top

        1. To print file file:

               lp −c file

        2. To print multiple files with headers:

               pr file1 file2 | lp

RATIONALE         top

       The lp utility was designed to be a basic version of a utility that
       is already available in many historical implementations. The standard
       developers considered that it should be implementable simply as:

           cat "$@" > /dev/lp

       after appropriate processing of options, if that is how the
       implementation chose to do it and if exclusive access could be
       granted (so that two users did not write to the device
       simultaneously).  Although in the future the standard developers may
       add other options to this utility, it should always be able to
       execute with no options or operands and send the standard input to an
       unspecified output device.

       This volume of POSIX.1‐2008 makes no representations concerning the
       format of the printed output, except that it must be ``human-
       readable'' and ``non-volatile''.  Thus, writing by default to a disk
       or tape drive or a display terminal would not qualify. (Such
       destinations are not prohibited when −d dest, LPDEST, or PRINTER are
       used, however.)

       This volume of POSIX.1‐2008 is worded such that a ``print job''
       consisting of multiple input files, possibly in multiple copies, is
       guaranteed to print so that any one file is not intermixed with
       another, but there is no statement that all the files or copies have
       to print out together.

       The −c option may imply a spooling operation, but this is not
       required. The utility can be implemented to wait until the printer is
       ready and then wait until it is finished. Because of that, there is
       no attempt to define a queuing mechanism (priorities, classes of
       output, and so on).

       On some historical systems, the request ID reported on the STDOUT can
       be used to later cancel or find the status of a request using
       utilities not defined in this volume of POSIX.1‐2008.

       Although the historical System V lp and BSD lpr utilities have
       provided similar functionality, they used different names for the
       environment variable specifying the destination printer.  Since the
       name of the utility here is lp, LPDEST (used by the System V lp
       utility) was given precedence over PRINTER (used by the BSD lpr
       utility). Since environments of users frequently contain one or the
       other environment variable, the lp utility is required to recognize
       both. If this was not done, many applications would send output to
       unexpected output devices when users moved from system to system.

       Some have commented that lp has far too little functionality to make
       it worthwhile. Requests have proposed additional options or operands
       or both that added functionality. The requests included:

        *  Wording requiring the output to be ``hardcopy''

        *  A requirement for multiple printers

        *  Options for supporting various page-description languages

       Given that a compliant system is not required to even have a printer,
       placing further restrictions upon the behavior of the printer is not
       useful. Since hardcopy format is so application-dependent, it is
       difficult, if not impossible, to select a reasonable subset of
       functionality that should be required on all compliant systems.

       The term unspecified is used in this section in lieu of
       implementation-defined as most known implementations would not be
       able to make definitive statements in their conformance documents;
       the existence and usage of printers is very dependent on how the
       system administrator configures each individual system.

       Since the default destination, device type, queuing mechanisms, and
       acceptable forms of input are all unspecified, usage guidelines for
       what a conforming application can do are as follows:

        *  Use the command in a pipeline, or with −c, so that there are no
           permission problems and the files can be safely deleted or
           modified.

        *  Limit output to text files of reasonable line lengths and
           printable characters and include no device-specific formatting
           information, such as a page description language. The meaning of
           ``reasonable'' in this context can only be answered as a quality-
           of-implementation issue, but it should be apparent from
           historical usage patterns in the industry and the locale. The pr
           and fold utilities can be used to achieve reasonable formatting
           for the default page size of the implementation.

       Alternatively, the application can arrange its installation in such a
       way that it requires the system administrator or operator to provide
       the appropriate information on lp options and environment variable
       values.

       At a minimum, having this utility in this volume of POSIX.1‐2008
       tells the industry that conforming applications require a means to
       print output and provides at least a command name and LPDEST routing
       mechanism that can be used for discussions between vendors,
       application developers, and users. The use of ``should'' in the
       DESCRIPTION of lp clearly shows the intent of the standard
       developers, even if they cannot mandate that all systems (such as
       laptops) have printers.

       This volume of POSIX.1‐2008 does not specify what the ownership of
       the process performing the writing to the output device may be. If −c
       is not used, it is unspecified whether the process performing the
       writing to the output device has permission to read file if there are
       any restrictions in place on who may read file until after it is
       printed. Also, if −c is not used, the results of deleting file before
       it is printed are unspecified.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       mailx(1p)

       The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment
       Variables, Section 12.2, Utility Syntax Guidelines

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) In the event of any discrepancy between this version and
       the original IEEE and The Open Group Standard, the original IEEE and
       The Open Group Standard is the referee document. The original
       Standard can be obtained online at http://www.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the
       source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                 2013                              LP(1P)

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