SLEEP(1)                   POSIX Programmer's Manual                  SLEEP(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
       sleep -- suspend execution for an interval

SSYYNNOOPPSSIISS
       sleep _t_i_m_e

DDEESSCCRRIIPPTTIIOONN
       The _s_l_e_e_p utility shall suspend execution for at least the integral
       number of seconds specified by the _t_i_m_e operand.

OOPPTTIIOONNSS
       None.

OOPPEERRAANNDDSS
       The following operand shall be supported:

       _t_i_m_e      A non-negative decimal integer specifying the number of
                 seconds for which to suspend execution.

SSTTDDIINN
       Not used.

IINNPPUUTT FFIILLEESS
       None.

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

       _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
       If the _s_l_e_e_p utility receives a SIGALRM signal, one of the following
       actions shall be taken:

        1. Terminate normally with a zero exit status.

        2. Effectively ignore the signal.

        3. Provide the default behavior for signals described in the
           ASYNCHRONOUS EVENTS section of _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.  This could include terminating with a non-zero exit
           status.

       The _s_l_e_e_p utility shall take the standard action for all other signals.

SSTTDDOOUUTT
       Not used.

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    The execution was successfully suspended for at least _t_i_m_e
             seconds, or a SIGALRM signal was received. See the ASYNCHRONOUS
             EVENTS section.

       >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
       None.

EEXXAAMMPPLLEESS
       The _s_l_e_e_p utility can be used to execute a command after a certain
       amount of time, as in:


           (sleep 105; _c_o_m_m_a_n_d) &

       or to execute a command every so often, as in:


           while true
           do
               _c_o_m_m_a_n_d
               sleep 37
           done

RRAATTIIOONNAALLEE
       The exit status is allowed to be zero when _s_l_e_e_p is interrupted by the
       SIGALRM signal because most implementations of this utility rely on the
       arrival of that signal to notify them that the requested finishing time
       has been successfully attained. Such implementations thus do not
       distinguish this situation from the successful completion case. Other
       implementations are allowed to catch the signal and go back to sleep
       until the requested time expires or to provide the normal signal
       termination procedures.

       As with all other utilities that take integral operands and do not
       specify subranges of allowed values, _s_l_e_e_p is required by this volume
       of POSIX.1-2017 to deal with _t_i_m_e requests of up to 2147483647 seconds.
       This may mean that some implementations have to make multiple calls to
       the delay mechanism of the underlying operating system if its argument
       range is less than this.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _w_a_i_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

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

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                             SLEEP(1)
