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



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

NNAAMMEE
       tee -- duplicate standard input

SSYYNNOOPPSSIISS
       tee [[-ai]] [[_f_i_l_e...]]

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

       If the --aa option is not specified, output files shall be written (see
       _S_e_c_t_i_o_n _1_._1_._1_._4, _F_i_l_e _R_e_a_d, _W_r_i_t_e, _a_n_d _C_r_e_a_t_i_o_n.

OOPPTTIIOONNSS
       The _t_e_e utility shall conform to the Base Definitions volume of
       POSIX.1-2017, _S_e_c_t_i_o_n _1_2_._2, _U_t_i_l_i_t_y _S_y_n_t_a_x _G_u_i_d_e_l_i_n_e_s.

       The following options shall be supported:

       --aa        Append the output to the files.

       --ii        Ignore the SIGINT signal.

OOPPEERRAANNDDSS
       The following operands shall be supported:

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

SSTTDDIINN
       The standard input can be of any type.

IINNPPUUTT FFIILLEESS
       None.

EENNVVIIRROONNMMEENNTT VVAARRIIAABBLLEESS
       The following environment variables shall affect the execution of _t_e_e:

       _L_A_N_G      Provide a default value for the internationalization
                 variables that are unset or null. (See the Base Definitions
                 volume of POSIX.1-2017, _S_e_c_t_i_o_n _8_._2, _I_n_t_e_r_n_a_t_i_o_n_a_l_i_z_a_t_i_o_n
                 _V_a_r_i_a_b_l_e_s for the precedence of internationalization
                 variables used to determine the values of locale categories.)

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

       _L_C___C_T_Y_P_E  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).

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

       _N_L_S_P_A_T_H   Determine the location of message catalogs for the processing
                 of _L_C___M_E_S_S_A_G_E_S.

AASSYYNNCCHHRROONNOOUUSS EEVVEENNTTSS
       Default, except that if the --ii option was specified, SIGINT shall be
       ignored.

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

SSTTDDEERRRR
       The standard error shall be used only for diagnostic messages.

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

EEXXTTEENNDDEEDD DDEESSCCRRIIPPTTIIOONN
       None.

EEXXIITT SSTTAATTUUSS
       The following exit values shall be returned:

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

       >0    An error occurred.

CCOONNSSEEQQUUEENNCCEESS OOFF EERRRROORRSS
       If a write to any successfully opened _f_i_l_e operand fails, writes to
       other successfully opened _f_i_l_e operands and standard output shall
       continue, but the exit status shall be non-zero. Otherwise, the default
       actions specified in _S_e_c_t_i_o_n _1_._4, _U_t_i_l_i_t_y _D_e_s_c_r_i_p_t_i_o_n _D_e_f_a_u_l_t_s apply.

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

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

       The _f_i_l_e operand is technically optional, but _t_e_e is no more useful
       than _c_a_t when none is specified.

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


           ... | tee unsorted | sort > sorted

RRAATTIIOONNAALLEE
       The buffering requirement means that _t_e_e is not allowed to use ISO C
       standard fully buffered or line-buffered writes. It does not mean that
       _t_e_e 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 --ii.  They also
       print a message if unable to open a file:


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

       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 _l_s_e_e_k() 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 _S_e_c_t_i_o_n _1_._1_._1_._4, _F_i_l_e
       _R_e_a_d, _W_r_i_t_e, _a_n_d _C_r_e_a_t_i_o_n.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _C_h_a_p_t_e_r _1, _I_n_t_r_o_d_u_c_t_i_o_n, _c_a_t

       The Base Definitions volume of POSIX.1-2017, _C_h_a_p_t_e_r _8, _E_n_v_i_r_o_n_m_e_n_t
       _V_a_r_i_a_b_l_e_s, _S_e_c_t_i_o_n _1_2_._2, _U_t_i_l_i_t_y _S_y_n_t_a_x _G_u_i_d_e_l_i_n_e_s

       The System Interfaces volume of POSIX.1-2017, _l_s_e_e_k()

CCOOPPYYRRIIGGHHTT
       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(1)
