sleep ===== NAME ---- sleep - suspend execution for an interval SYNOPSIS -------- **sleep** time DESCRIPTION ----------- The sleep utility shall suspend execution for at least the integral number of seconds specified by the time operand. OPTIONS ------- None. OPERANDS -------- The following operand shall be supported: **time** A non-negative decimal integer specifying the number of seconds for which to suspend execution. STDIN ----- Not used. INPUT FILES ----------- None. ENVIRONMENT VARIABLES ------------------------ The following environment variables shall affect the execution of cat: **LANG** Provide a default value for the internationalization variables that are unset or null. (See the Base Definitions volume of IEEE Std 1003.1-2001, 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 ------------------- Default STDOUT ------ Not used. STDERR ------ The standard error shall be used only for diagnostic messages. OUTPUT FILES ------------ None. EXTENDED DESCRIPTION -------------------- None. EXIT STATUS ----------- The following exit values shall be returned: **0** All input files were output successfully. **>0** An error occurred. CONSEQUENCES OF ERRORS ---------------------- Default. The following sections are informative. APPLICATION USAGE ----------------- None. EXAMPLES -------- The sleep utility can be used to execute a command after a certain amount of time, as in: .. code:: bash (sleep 105; command) & or to execute a command every so often, as in: .. code:: bash while true do command sleep 37 done RATIONALE --------- The exit status is allowed to be zero when sleep 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, sleep is required by this volume of IEEE Std 1003.1-2001 to deal with time 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. FUTURE DIRECTIONS ----------------- None. SEE ALSO -------- wait , the System Interfaces volume of IEEE Std 1003.1-2001, alarm(), sleep() COPYRIGHT --------- * Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 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 . * Copyright © 2006-2013 – Source Powered by `Damien Pobel `_, `from here `_ * Copyright © 2020-2021 – Powered by `Galaxie Shell Project `_, `rst `_ conversion