coreutils: sleep invocation

 
 25.1 ‘sleep’: Delay for a specified time
 ========================================
 
 ‘sleep’ pauses for an amount of time specified by the sum of the values
 of the command line arguments.  Synopsis:
 
      sleep NUMBER[smhd]...
 
    Each argument is a non-negative number followed by an optional unit;
 the default is seconds.  The units are:
 
 ‘s’
      seconds
 ‘m’
      minutes
 ‘h’
      hours
 ‘d’
      days
 
    Although portable POSIX scripts must give ‘sleep’ a single
 non-negative integer argument without a suffix, GNU ‘sleep’ also accepts
 two or more arguments, unit suffixes, and floating-point numbers in
 either the current or the C locale.  ⇒Floating point.
 
    For instance, the following could be used to ‘sleep’ for 1 second,
 234 milli-, 567 micro- and 890 nanoseconds:
 
      sleep 1234e-3 567.89e-6
 
    The only options are ‘--help’ and ‘--version’.  ⇒Common
 options.
 
    Due to shell aliases and built-in ‘sleep’ functions, using an
 unadorned ‘sleep’ interactively or in a script may get you different
 functionality than that described here.  Invoke it via ‘env’ (i.e., ‘env
 sleep ...’) to avoid interference from the shell.
 
    An exit status of zero indicates success, and a nonzero value
 indicates failure.