Sleep

The sleep utility shall suspend execution for at least the integral number of seconds specified by the time operand. A non-negative decimal integer specifying the number of seconds for which to suspend execution. Provide a default value for the internationalization variables that are unset or null. (See XBD Internationalization Variables for the precedence of internationalization variables used to determine the values of locale categories.) If set to a non-empty string value, override the values of all the other internationalization variables. Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error. [XSI) ] ![[Option Start]]( Determine the location of message catalogs for the processing of LC MESSAGES. ![[Option End]]( 3. Provide the default behavior for signals described in the ASYNCHRONOUS EVENTS section of Utility Description Defaults . This could include terminating with a non-zero exit status. The sleep utility shall take the standard action for all other signals. The execution was successfully suspended for at least time seconds, or a SIGALRM signal was received. See the ASYNCHRONOUS EVENTS section. 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 POSIX.1-2017 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.