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/usr/bin/sleep seconds
sleep seconds
sleep suspends execution for at least the time in seconds specified by seconds or until a SIGALRM signal is received. The seconds operand can be specified as a floating point number but the actual granularity normally depends on the underlying system.
The following operands are supported for /usr/bin/sleep and ksh93's sleep built-in command:
seconds
A non-negative floating-point number specifying the number of seconds for which to suspend execution. The floating-point number may be specified in all formats required by C99/XPG6, including constants such as "Inf" or "infinite".
The following operands are supported:
time
Specify time in seconds as a floating point number. The actual granularity depends on the underlying system, normally around 1 millisecond.
Example 1 Suspending Command Execution
The following example executes a command after a certain amount of time:
example% (sleep 105; command)&
Example 2 Executing a Command Every So Often
The following example executes a command every so often:
example% while true
do
command
sleep 37
done
Example 3 Suspend command execution forever (or until a SIGALRM signal is received)
example% sleep Inf
Example 4 Suspending command execution for 0.5 seconds
Suspending command execution for 0.5 seconds using an alternative floating-point representation for the value "0.5"
example% printf "%a\n" 0.5 0x1.0000000000000000000000000000p-01
example% sleep 0x1.0000000000000000000000000000p-01
See environ(5) for descriptions of the following environment variables that affect the execution of sleep: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES, and NLSPATH.
The following exit values are returned:
0
The execution was successfully suspended for at least time seconds, or a SIGALRM signal was received (see NOTES).
>0
An error has occurred.
See attributes(5) for descriptions of the following attributes:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Interface Stability | Committed |
| Standard | See standards(5). |
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Interface Stability | Uncommitted |
ksh93(1), wait(1), alarm(2), sleep(3C), wait(3UCB), attributes(5), environ(5), standards(5)
If the sleep utility receives a SIGALRM signal, one of the following actions is taken:
Terminate normally with a zero exit status.
Effectively ignore the signal.
The sleep utility takes the standard action for all other signals.
The behavior for input values such as "NaN" (not-a-number) or negative values is undefined.