This is the command sleepenh that can be run in the OnWorks free hosting provider using one of our multiple free online workstations such as Ubuntu Online, Fedora Online, Windows online emulator or MAC OS online emulator
PROGRAM:
NAME
sleepenh - an enhanced sleep program
SYNOPSIS
sleepenh [[--warp|-w] INITIALTIME] TIMETOSLEEP
DESCRIPTION
sleepenh is a program that can be used when there is a need to execute some functions
periodically in a shell script. It was not designed to be accurate for a single sleep, but
to be accurate in a sequence of consecutive sleeps.
After a successful execution, it returns to stdout the timestamp it finished running, that
can be used as INITIALTIME to a successive execution of sleepenh.
OPTIONS
-h, --help
display this help and exit
-w, --warp
warp resulting timestamp, when there is no need to sleep. An immediatly following
call of sleepenh with the resulting TIMESTAMP would most probably result in a real
sleep.
-V, --version
output version information and exit
ARGUMENTS
TIMETOSLEEP is a real number in seconds, with microseconds resolution (1 minute, 20
seconds and 123456 microseconds would be 80.123456).
INITIALTIME is a real number in seconds, with microseconds resolution. This number is
system dependent. In GNU/Linux systems, it is the number of seconds since midnight
1970-01-01 GMT. Do not try to get a good value of INITIALTIME. Use the value supplied by a
previous execution of sleepenh.
If you don't specify INITIALTIME, it is assumed the current time.
EXIT STATUS
An exit status greater or equal to 10 means failure. Known exit status:
0 Success.
1 Success. There was no need to sleep. (means that INITIALTIME + TIMETOSLEEP was
greater than current time).
10 Failure. Missing command line arguments.
11 Failure. Did not receive SIGALRM.
12 Failure. Argument is not a number.
13 Failure. System error, could not get current time.
USAGE EXAMPLE
Suppose you need to send the char 'A' to the serial port ttyS0 every 4 seconds. This will
do that:
#!/bin/sh
TIMESTAMP=`sleepenh 0`
while true; do
# send the byte to ttyS0
echo -n "A" > /dev/ttyS0;
# just print a nice message on screen
echo -n "I sent 'A' to ttyS0, time now is ";
sleepenh 0;
# wait the required time
TIMESTAMP=`sleepenh $TIMESTAMP 4.0`;
done
HINT
This program can be used to get the current time. Just execute:
sleepenh 0
Use sleepenh online using onworks.net services
