UNEXPAND(1)                POSIX Programmer's Manual               UNEXPAND(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
       unexpand -- convert spaces to tabs

SSYYNNOOPPSSIISS
       unexpand [[-a|-t _t_a_b_l_i_s_t]] [[_f_i_l_e...]]

DDEESSCCRRIIPPTTIIOONN
       The _u_n_e_x_p_a_n_d utility shall copy files or standard input to standard
       output, converting <blank> characters at the beginning of each line
       into the maximum number of <tab> characters followed by the minimum
       number of <space> characters needed to fill the same column positions
       originally filled by the translated <blank> characters. By default,
       tabstops shall be set at every eighth column position. Each <backspace>
       shall be copied to the output, and shall cause the column position
       count for tab calculations to be decremented; the count shall never be
       decremented to a value less than one.

OOPPTTIIOONNSS
       The _u_n_e_x_p_a_n_d 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        In addition to translating <blank> characters at the
                 beginning of each line, translate all sequences of two or
                 more <blank> characters immediately preceding a tab stop to
                 the maximum number of <tab> characters followed by the
                 minimum number of <space> characters needed to fill the same
                 column positions originally filled by the translated <blank>
                 characters.

       --tt _t_a_b_l_i_s_t
                 Specify the tab stops. The application shall ensure that the
                 _t_a_b_l_i_s_t option-argument is a single argument consisting of a
                 single positive decimal integer or multiple positive decimal
                 integers, separated by <blank> or <comma> characters, in
                 ascending order. If a single number is given, tabs shall be
                 set _t_a_b_l_i_s_t column positions apart instead of the default 8.
                 If multiple numbers are given, the tabs shall be set at those
                 specific column positions.

                 The application shall ensure that each tab-stop position _N is
                 an integer value greater than zero, and the list shall be in
                 strictly ascending order. This is taken to mean that, from
                 the start of a line of output, tabbing to position _N shall
                 cause the next character output to be in the (_N+1)th column
                 position on that line. When the --tt option is not specified,
                 the default shall be the equivalent of specifying --tt 88
                 (except for the interaction with --aa, described below).

                 No <space>-to-<tab> conversions shall occur for characters at
                 positions beyond the last of those specified in a multiple
                 tab-stop list.

                 When --tt is specified, the presence or absence of the --aa
                 option shall be ignored; conversion shall not be limited to
                 the processing of leading <blank> characters.

OOPPEERRAANNDDSS
       The following operand shall be supported:

       _f_i_l_e      A pathname of a text file to be used as input.

SSTTDDIINN
       See the INPUT FILES section.

IINNPPUUTT FFIILLEESS
       The input files shall be text files.

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

       _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 and input
                 files), the processing of <tab> and <space> characters, and
                 for the determination of the width in column positions each
                 character would occupy on an output device.

       _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.

SSTTDDOOUUTT
       The standard output shall be equivalent to the input files with the
       specified <space>-to-<tab> conversions.

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

OOUUTTPPUUTT FFIILLEESS
       None.

EEXXTTEENNDDEEDD DDEESSCCRRIIPPTTIIOONN
       None.

EEXXIITT SSTTAATTUUSS
       The following exit values shall be returned:

        0    Successful completion.

       >0    An error occurred.

CCOONNSSEEQQUUEENNCCEESS OOFF EERRRROORRSS
       Default.

       _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
       One non-intuitive aspect of _u_n_e_x_p_a_n_d is its restriction to leading
       <space> characters when neither --aa nor --tt is specified. Users who
       always want to convert all <space> characters in a file can easily
       alias _u_n_e_x_p_a_n_d to use the --aa or --tt 88 option.

EEXXAAMMPPLLEESS
       None.

RRAATTIIOONNAALLEE
       On several occasions, consideration was given to adding a --tt option to
       the _u_n_e_x_p_a_n_d utility to complement the --tt in _e_x_p_a_n_d (see _e_x_p_a_n_d).  The
       historical intent of _u_n_e_x_p_a_n_d was to translate multiple <blank>
       characters into tab stops, where tab stops were a multiple of eight
       column positions on most UNIX systems. An early proposal omitted --tt
       because it seemed outside the scope of the User Portability Utilities
       option; it was not described in any of the base documents for IEEE Std
       1003.2-1992.  However, hard-coding tab stops every eight columns was
       not suitable for the international community and broke historical
       precedents for some vendors in the FORTRAN community, so --tt was
       restored in conjunction with the list of valid extension categories
       considered by the standard developers. Thus, _u_n_e_x_p_a_n_d is now the
       logical converse of _e_x_p_a_n_d.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _e_x_p_a_n_d, _t_a_b_s

       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

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                          UNEXPAND(1)
