tee(1p) — Linux manual page

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

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

       tee — duplicate standard input

SYNOPSIS         top

       tee [-ai] [file...]

DESCRIPTION         top

       The tee utility shall copy standard input to standard output,
       making a copy in zero or more files. The tee utility shall not
       buffer output.

       If the -a option is not specified, output files shall be written
       (see Section 1.1.1.4, File Read, Write, and Creation.

OPTIONS         top

       The tee utility shall conform to the Base Definitions volume of
       POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.

       The following options shall be supported:

       -a        Append the output to the files.

       -i        Ignore the SIGINT signal.

OPERANDS         top

       The following operands shall be supported:

       file      A pathname of an output file. If a file operand is '-',
                 it shall refer to a file named -; implementations shall
                 not treat it as meaning standard output.  Processing of
                 at least 13 file operands shall be supported.

STDIN         top

       The standard input can be of any type.

INPUT FILES         top

       None.

ENVIRONMENT VARIABLES         top

       The following environment variables shall affect the execution of
       tee:

       LANG      Provide a default value for the internationalization
                 variables that are unset or null. (See the Base
                 Definitions volume of POSIX.1‐2017, 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).

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

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

ASYNCHRONOUS EVENTS         top

       Default, except that if the -i option was specified, SIGINT shall
       be ignored.

STDOUT         top

       The standard output shall be a copy of the standard input.

STDERR         top

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES         top

       If any file operands are specified, the standard input shall be
       copied to each named file.

EXTENDED DESCRIPTION         top

       None.

EXIT STATUS         top

       The following exit values shall be returned:

        0    The standard input was successfully copied to all output
             files.

       >0    An error occurred.

CONSEQUENCES OF ERRORS         top

       If a write to any successfully opened file operand fails, writes
       to other successfully opened file operands and standard output
       shall continue, but the exit status shall be non-zero. Otherwise,
       the default actions specified in Section 1.4, Utility Description
       Defaults apply.

       The following sections are informative.

APPLICATION USAGE         top

       The tee utility is usually used in a pipeline, to make a copy of
       the output of some utility.

       The file operand is technically optional, but tee is no more
       useful than cat when none is specified.

EXAMPLES         top

       Save an unsorted intermediate form of the data in a pipeline:

           ... | tee unsorted | sort > sorted

RATIONALE         top

       The buffering requirement means that tee is not allowed to use
       ISO C standard fully buffered or line-buffered writes. It does
       not mean that tee has to do 1-byte reads followed by 1-byte
       writes.

       It should be noted that early versions of BSD ignore any invalid
       options and accept a single '-' as an alternative to -i.  They
       also print a message if unable to open a file:

           "tee: cannot access %s\n", <pathname>

       Historical implementations ignore write errors. This is
       explicitly not permitted by this volume of POSIX.1‐2017.

       Some historical implementations use O_APPEND when providing
       append mode; others use the lseek() function to seek to the end-
       of-file after opening the file without O_APPEND. This volume of
       POSIX.1‐2017 requires functionality equivalent to using O_APPEND;
       see Section 1.1.1.4, File Read, Write, and Creation.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       Chapter 1, Introduction, cat(1p)

       The Base Definitions volume of POSIX.1‐2017, Chapter 8,
       Environment Variables, Section 12.2, Utility Syntax Guidelines

       The System Interfaces volume of POSIX.1‐2017, lseek(3p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  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.opengroup.org/unix/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               2017                           TEE(1P)